FDA warning against DIY systems

I’d like to address, in my own opinions, the recent announcement of the FDA warning “against the use of devices for diabetes management not authorized for sale in the United States”.

First, there’s a lot of rumors out there and the headlines from the various places trying to “explain” the situation do little to actually give good information. I just did a search to find the link above and let’s just look at those headlines…how many were misleading ledes or otherwise really not getting the whole message correctly explained.

About the only article that really gets it right is the JDRF statement. But, the average person trying to sift through the information this is a very confusing topic admittedly…so let’s pull out some of the specific quotes from the FDA warning and talk about what they mean in plain terms. This really wasn’t about DIY closed loop systems causing harm (although that could be part of it, depending on the situation)…the underlying cause of the warning was about DIY CGM apps.

“The FDA received a report of a serious adverse event in which a patient used an unauthorized device that receives the electronic signal from an FDA authorized glucose sensor and converts it to a glucose value using an unauthorized algorithm. Glucose values from this unauthorized continuous glucose monitoring system were sent to an unauthorized automated insulin dosing device to drive insulin dosing. The automated insulin dosing system gave too much insulin in response to repeated incorrect high glucose values sent from the [unauthorized] continuous glucose monitoring system (emphasis added). This unauthorized system resulted in an insulin overdose requiring medical intervention. ”

Before we can look at what this means…it would be helpful for many people to have a really basic introduction to continuous glucose monitors (and this is the really layman version).

CGM basics

Glucose sensors don’t actually read a blood glucose reading. Instead they read a “raw signal,” basically an electrical signal from the fluid surrounding the sensor wire. That raw signal is then converted to a “blood glucose reading” by an algorithm. The algorithm that does that job is a HUGE chunk of work by the company that makes the sensor. They do lots of design, testing, clinical trials, and reworking on that algorithm. That algorithm is really, really important for demonstrating that the sensor will be safe for the users in a variety of situations. For example compression lows, poorly timed calibrations, and rapid temperature changes are just some of the difficult situations that an algorithm will need to deal with.

Dexcom sensors showing ??? or “sensor error, wait up to 3 hours”…that is actually a part of the safety algorithm. The sensor wire’s raw signals are either varying wildly, perhaps the calibration entered is way out of its expected bounds, or the temperature suddenly shifted a lot. The sensor algorithm is rightly telling you “Hey, I’m unsure about telling you a number and I don’t want you doing something unsafe with a number I’m not sure about. Give me a chance to see if the raw signals settle down again.”

All sensors on the market have safety checks and sensor failure communications built into their algorithms. They also have enforced end-of-sensor (for example, Dexcom G6 is 10 days) timing in the apps. These features are all part of the safety of using CGMs for diabetes management decisions, and they undergo FDA review.

X-Drip and Spike Apps

Have you ever just wanted to avoid the ??? or enforced end-of-sensor sessions? I know you have because this blog’s post on how to restart a Dexcom G6 is one of the most popular blog posts I’ve ever written.

There’s two DIY CGM apps on the market that avoid those ??? and session ends. The apps (X-drip for Android phones and Spike app for iPhones) are popular in part because they offer the ability to just “always get CGM data”. While nice on the surface, those features can present a problem potentially…and that’s what the FDA warning was all about.

X-drip and Spike use their own algorithms to handle the raw signals. Calibrations, temperature variations, sensor noise, sensor failure notifications and other variables within the algorithm are not clinically-tested for those apps. (note: Generally, X-drip and Spike use the same algorithms between the two apps for several of the supported CGM devices. Therefore, X-drip and Spike are generally going to behave the same when we are discussing the general topic of DIY CGM apps.)

Reported Adverse Event

So what happened to trigger the FDA warning?

Plain and simple…a person was using a Libre sensor on one of these DIY CGM apps. Libre sensors are not continuous glucose monitoring devices. They are flash glucose monitors. In order to make them into continuous glucose monitors, some people have used non-FDA approved devices that sit on top of the Libre sensor to emulate someone “flashing” their Libre for a reading.  Those devices you probably recognize as either the Miao Miao or Blucon readers.

Since these readers are not officially associated with Libre sensors…there’s also no clinically-tested, FDA-approved app to receive the information from these readers. And this is where the warning comes in:

“The FDA received a report of a serious adverse event in which a patient used an unauthorized device that receives the electronic signal from an FDA authorized glucose sensor and converts it to a glucose value using an unauthorized algorithm….repeated incorrect high glucose values [were] sent from the [unauthorized] continuous glucose monitoring system…”

Someone using (1) a Miao Miao reader and (2) a Libre sensor and (3) a DIY CGM app had a situation where the sensor failed. Instead of the sensor failing by then reporting no data (such as ??? or “sensor error” like Dexcom), the DIY CGM app showed incorrectly high BG readings.

What does this look like?

The image above is from another recent report very similar to the one discussed in the FDA warning (minus the need for medical intervention). Details of this event can be found in the OpenAPS Github repository.

The user had Miao Miao + Libre sensor + DIY CGM app. The recently restarted sensor started to fail with a drift. The user, rather than pull the failing sensor, tried to calibrate the sensor to the 16 mmol (about 288 mg/dL) value shown near 10am. The failed sensor took the calibration and remained virtually stuck. The DIY CGM app continued to report nearly 16 mmol for 8 hours…

So, let’s stop there and assess.

  • Are we irritated when sensors stop providing data and instead say ??? or “sensor error”? Yes.
  • Are sensors expensive and we try to get them to work as long as they can? Yes, many people do.

But, if automated insulin dosing is also a part of someone’s DIY CGM app use…those safety factors (and your ability to do without them) may need to be re-evaluated in terms of whether or not you want to continue to make insulin dosing decisions on them. Can commercial CGM algorithms still get data wrong? Yes, but it is far less common these days…and if they do get data wrong, it is very unlikely to be so “off” that an automated insulin delivery system would cause a hypoglycemic event serious enough to cause medical intervention.

Automated Insulin Delivery

The FDA-reported problem of the failed sensor still sending bad CGM readings through the DIY CGM app…it affected the user’s DIY closed-loop automated insulin delivery and caused the system to over-deliver insulin. The user needed hospitalization for the hypoglycemic event that occurred as a result.

The figure above with the 16 mmol? See below the royal blue marks at the bottom of the figure? Those were automated insulin microboluses delivered by the user’s OpenAPS system to try to bring down the 16 mmol. If unnoticed by the user, those insulin deliveries could have caused hypoglycemia.

Is this potential to over-deliver (or under-deliver) insulin unique to DIY closed-loop systems? Nope, absolutely not. And that is the message that all this news coverage is missing. The REAL story. Access to quality CGM devices is the underlying need to be addressed.

Any automated, closed-loop system (commercial or DIY) will only be as good as the CGM data that is feeding the system.

Medtronic’s 670G system will kick users out of automode when their algorithm has sensor issues. All commercial closed loop systems will have safety checks that if the CGM part of the system reports an error…you’ll be kicked back to old-school insulin dosing decisions.

CGM Data is Critical

Now that we’ve addressed the background, it is pretty obvious just how important keeping quality CGM data is if you choose to use any closed-loop system.

Only one iCGM system, the Dexcom G6, is currently FDA-approved for eventual automated insulin dosing across future integrated pump/loop systems (Medtronic’s 670G’s Guardian 3 sensor is approved only for their system in particular). This is the system we use and I love it. I feel very safe with its use and messaging. The first 8-12 hours are a little jumpy and I can choose to open loop if I want to…but otherwise the sensor has proven to be exceptionally accurate for the 10 days we use it. Despite the fact I wrote the blog post about how to restart, we actually don’t restart our G6 sensors. Anna enjoys fresh clean adhesive and the insertion is so easy for her that it isn’t an impediment to change sensors any more.

Unfortunately, many areas outside the USA do not have access to or approval of Dexcom G6. This leaves them either incredibly expensive or entirely unavailable. The Libre sensors are more widely available and/or affordable in those markets…giving rise to this dilemma about DIY CGM apps.

Ideally, the FDA’s warning message hammers home a point that really is sorely true. The access to quality health tools to safely manage T1D is lacking. T1D is so inherently risky. The slowness of the world’s government systems to help with access and affordability of quality CGMs is adding to our community’s collective risk.

Dear FDA…if access and affordability of quality CGM systems were addressed, DIY CGM apps would not be needed. Adverse events can happen on your FDA-approved devices as well. T1D is risky with syringes and finger sticks through the most advanced FDA-approved closed loops. The warning is that diabetes is risky, and we need quicker iteration and better development in the commercial markets.

People might not necessarily want to use a Libre plus a reader plus a DIY app…but in some cases they’ve assessed their risk management baskets and decided that setup IS their best risk mitigation.

To those people, please…

  • be exceedingly careful about not extending sensors to beyond their safe lifespan,
  • make very careful calibration decisions,
  • watch for signs that the sensor wire as even partially pulled out of skin, and
  • if in doubt, change your sensor and take finger stick readings.

For us personally, we are grateful to have an iCGM (Dexcom G6) and that we can afford to change it regularly. We use the official Dexcom app because those times of “sensor error” or “???” provide a level of safety that I find appropriate, rather than an annoyance, since we are using a closed-loop. We replace sensors when they show any sign of failure, and I don’t feel in the least bit guilty about it. And the use of our DIY Loop app has decreased our overall risk exposure while managing T1D…but I can only say that because our CGM data is reliable. And that’s what the FDA warning was trying to tell you.

Juicebox Method to Loop

To all those who said hi to me from the Juicebox Podcast, thank you! I see you and hear you…(and hello similarly to Sugar Surfers…this post is also for you all…basically for everyone who tends to “know their boluses”.)

You may have heard my jaw drop on the floor just a touch during the podcast when Scott asked if he needed to count carbs and know his carb ratio in order to Loop…and I think it’s time to write up a blog post to help you all transition from what I’ll call the Juicebox method to Loop. Because yes, you need to know your carb ratio and carb estimate. I’ve noticed for many of you this may be quite an adjustment if you don’t have a head’s up about how to make this transition from where you are with insulin surfing.

Why? Because you all have been insulin surfing without settings (and no, I am not typing that in a derogatory fashion). There’s a book called Sugar Surfing that has the same general underpinnings as what Scott his podcast are really good at explaining for the Juicebox method…think dynamically and react according to what you are seeing. Scott’s coined phrase is “Be Bold with Insulin” and it’s allowed a lot of people to transition from feeling like they need a restricted diet to meet A1C goal, and instead eating higher carb meals quite successfully and getting more consistent results. I’m a big proponent to this concept…it is basically the idea of lining up the insulin dosing so that it is most effective against carbs rather than restricting carbs. Even low carbers have also embraced this concept of lining up insulin and carbs appropriately by using R-insulin (slower, longer peak action time) and eating slower foods like proteins and fats…so the concept crosses a lot of user groups similarly.

The rub is that what if someone else was doing the reacting and thinking dynamically for you so that you could take a break? You can’t react while you’re asleep. Your kid doesn’t want to react while taking their math test. And all the button presses you can save?! That’s what Loop does 24/7 even while you sleep.

BUT…to get Loop to react, you need to feed it information about yourself and your diabetes. That information you’re going to feed Loop is your settings; basal rates, carb ratios, insulin sensitivity factor (ISF, sometimes called correction factor). And this is where Juicebox users will perhaps run into trouble because the method approaches diabetes from the end result (how much insulin to give) rather than the beginning (what settings will affect how much insulin to give). So, how can we get you from managing at the end result (insulin) and shift you to the beginning (settings and meal entries)?

Let me give you an example to help illustrate. Enter friend Jane Doe.

I set up a good friend, Jane, on Omnipod Loop before it was publicly released. I’ve known her for a long time and she has a little daughter, Princess Buttercup, with type 1. My intent was to see how the docs would work for Jane and fix places where she told me it was not clear enough to a new user. Also, I wanted feedback on what common pitfalls in the Loop app might be for new Omnipod Loop users and such. She was my canary in a coal mine (thanks Jane!).

Jane had been using the Bold With Insulin approach for eating for a long time. She knew which foods her daughter ate and how to administer insulin. Meals had a predictable good result. But, she didn’t count carbs much and didn’t know her settings really. Her endo had given her some PDM settings, but they were never really tested because she didn’t use them. Meals didn’t use a carb count and corrections for out-of-range or changing BGs were done by “feel” based on how quickly BGs were changing, not through calculating insulin on board and ISF. If she saw a slight climb in CGM, she’d have a manual bolus “feeling” based on so many times she’d corrected before in the same situations. If the climb was steeper, she’d manually give more insulin, also based on previous experience. The only setting that got any kind of real use was basal rates…but even those were frequently being overrun manually with temp basal rates she’d enact herself.

I asked her how new meals that she’d never tried before would go. Jane described that there would be a first guess at a bolus based roughly on similar other meals with those similar types of ingredients. She’d watch the CGM and adjust insulin manually. She’d track in her head how those adjustments worked out and the next time she bolused for the same meal, Jane would try to use what she’d learned from the meal the previous time. This meant that new foods were kind of a learning experiment, but she’d pretty quickly dial-in a “known dosing” for the new food within a few tries.

A couple days into using Loop, Jane was pretty frustrated but I hadn’t known it. She was trying to figure it out on her own (she is a smart cookie) and something just wasn’t clicking.

In almost a straw-that-broke-the-camel’s-back moment, it was a bagel that finally made her ask what was going on with Loop and why this wasn’t working. And that opened up my eyes to the Bold With Insulin approach she’d been using and where that transition needed help.

Here’s the rough conversation (and it would probably be very, very similar to a convos any one of you could have as you transition):

Jane: I’m so frustrated. I can’t figure out where I’m going wrong. She had a bagel. Prebolused. Typically a food I bolus well for, like never above 150. (And a screenshot of a definitely-well-over-150 dexcom graph.)

Me: How many units would you have bolused for normally for that meal?

Jane: Normally, I would have dosed 1.25 units like I did this time, but I would have doubled her basal for awhile. This time when I gave the 1.25 units, Loop suspended insulin while she was waiting out the prebolus time.

And that conversation gave me a lot of insight into the issue.

  • Carb counts weren’t a big (or even small) part of her method on a regular basis
  • Bolusing was all being done with tools no longer available in Loop (extended boluses and temp basals)
  • Carb ratio wasn’t even used…she just had the boluses memorized for given meals.

So how has Jane turned it around? (Princess Buttercup has had a 0.5% A1C drop in two months of Looping now and Jane’s getting sleep)

Jane rolled up her sleeves and got to work on her settings.

If you are in Jane’s shoes and want to set yourself up for an easier transition, here’s a few tips you can do now.

Settings Testing

To transition successfully to Loop, Juiceboxers and Sugar Surfers alike are going to need to do some settings testing and meal deconstruction. Likely in open loop for a bit if you want to keep your frustrations down to a minimum.

This means not correcting immediately when you are testing basal rates for example. This means doing things in a sequential testing route…basals, carb ratios, insulin sensitivities in an ordered fashion. And also, you’ll need to look at how you’ve been successfully bolusing your meals and translate that to Loop.

It may take a couple weeks to finish the route…but the end result will be that you have decent settings to start with and Loop will be a less frustrating transition. Let’s start…

Work on your Basal Rates

Juiceboxers and Surfers have a lot of manual insulin adjustments running frequently. Temp basals and extended boluses are not at all uncommon.  Unfortunately, this is also a good chance to have difficulty in identifying if basals (especially daytime basals) are truly set correctly. There’s a high likelihood that all parts of your daytime are touched by insulin remaining from an extended or temp basal that ran within the last 6 hours.

When you get into food habits, and have “known boluses” for them, you can basically have two wrongs making a perfectly great right. For example, send kid to school with her favorite lunches every day and those boluses involving extended/temp basals…you might just be covering not only the food in the meal but also some basal needs from the day at school. Same for the breakfast you’ve been sending her out the door with. Or maybe you’re bolusing less for lunch than you’d typically need because she has PE class after lunch. Those are instances where having two compensating factors are showing a good result in BGs outside a Loop…but you may have problems when you go on Loop without truly knowing you were compensating for a settings issue.

Checking basals is a pretty easy starting place. Basals, in the absence of food and exercise, is the amount of insulin that should keep your blood glucose steady and flat.

So…test that. Go without food and exercise for a bit and see how that turns out. Start easy…these are kids and they won’t want to go without food (I get it). Perhaps start with some distractions to breakfast time. See if you can get 2-3 (or even 4 ?!) hours or so without a meal in the morning. Bribery works wonders here. Favorite video games, money, whatever. 😉 Do you notice a drift? Do BGs start to climb/drop without a breakfast bolus involved? If so, you will need to adjust your basals.

Do this check for a few times of day separately (morning, afternoon, night), if possible. Sleeping basals are the easiest to check since there usually isn’t food involved. But, if you can get a good morning basal test in…that will do WONDERS to helping get you off to a good start on settings during your transition. Did I mention the wonders of bribery? Seriously, if I were to invest money…basal testing is a great place to spend some money on your kid. Huge payback.

And hopefully this is obvious, don’t do basal testing if you are on steroids, medication, ill, or otherwise have something that is temporarily affecting your underlying insulin needs. Bad insulin sites and/or illness will not yield useful basal testing.

Personally, Anna has a basal rate that tends to be higher while she is awake vs asleep. Therefore on weekends (not school days), we can shift the start time of her “I’m awake” basal rate in Loop to match her sleeping-in habits. Anticipating your question: If we forget, it isn’t a big deal…Loop accommodates pretty well. Instead of hanging out at her 95 mg/dl target from 7am-10am on a weekend, she might hang out at 85-90 mg/dl if we forget to tell Loop she’s sleeping in. So, I don’t fret too much about telling Loop those kind of details…it’s up to you how you’d want to deal with that kind of details.

Work on your Carb Ratio

A well done meal bolus should bring you back to target BGs within three hours after a meal and not require low treatments as a result of the meal bolus. Pretty simple concept…difficult in execution for many. There’s a couple insights that really help with “successful” meal time BGs:

  • Prebolusing
  • Accounting for fats and proteins in total carb counts
  • Accounting for fats and proteins in the duration you need to bolus for

The good news is as a Juiceboxer and/or Sugar Surfer, you’re already likely doing those things. You have a good feel for bolusing. That’s a great thing. Don’t let that go to waste. What you need to do though is convert that knowledge into a carb ratio and meal entry so Loop can access that knowledge too.

Start as soon as you’ve completed your basal testing. Then try your meals again. When you have a meal…calculate how much TOTAL INSULIN you use on your Bold or Surfing method for the meal, including extended boluses and temp basals. In the bagel example, total bolus was 1.25 units up-front and another 1.5 units over two hours…so a total of 2.75 units for the bagel.

Now estimate the carbs for the amount of bagel you ate. Let’s say you ate 45g of bagel. Take the total grams and divide it by the total units…that is your carb ratio. 45/2.75 = 16 (rounded off). Therefore for every 16g of carbohydrates eaten, you’ll need one unit of insulin.

As a Juiceboxer, you probably have many meals you already know your bolus strategy for. Write out a list of them, look up some carb counts and do a table of calculated carb ratios. Do as many of your meals as you can think of. They should all roughly average out to about the same carb ratio. This would be an excellent place to start your carb ratio setting in Loop.

If you have meals with heavy fats and proteins, don’t forget that those often need some “equivalent carbs” added to the total count of carbs for the meal. For example, a protein bar may say 35g of carbs on the label…but I know that they are very heavy in protein and therefore I need to cover the carbs in that bar more than just 35g. As a juiceboxer, you’ve already done this by having a larger bolus for that bar than the first time you tried it…now you just need to realize it’s actually a larger carb count because of protein. For us, that protein bar really contains the equivalent of 60g carbs because the protein breaks down into sugar in the blood stream too.

So again…it’s a shift from thinking of things in the end result (insulin) to thinking of things from the beginning (settings and carb entries). Take your known insulin boluses and work backwards to your settings. If you have heavy protein meals, add some to your carb counts (perhaps 30-50% of the protein grams will convert to carb grams for estimations).

Work on Insulin Sensitivity Factor

Now the above example is really super exciting and an example of how great Loop can be…but that success also depended on one more critical factor you’ve yet to set; Insulin Sensitivity Factor (ISF), also called a Correction Factor in some systems.

Basically, your ISF is the amount of drop in BGs you can expect from one unit of insulin. That’s a pretty important value to Loop if you think about it in those terms. An awful lot of Loop’s decisions (in fact EVERY SINGLE ONE OF THEM) will depend on that setting in its calculations.

This ISF is a pretty simple concept, but also the most difficult to “get right” because experimenting and testing can be really hard if any of your other settings are wrong.

Unfortunately, this setting is also the place most new Loopers start with their adjustments (because they assume previous success means their settings were right…so it must be the ISF that is wrong?)…and they do it while in closed loop. Hint: DO NOT BE THAT NEW LOOPER. You may lose your marbles.

Instead, start in the sequence listed above…nail down those basal rates by testing them first or else messing with ISF will be counter-productive and you’ll go nuts.

Once you get basal rates set, you can test your ISF by taking a glucose tab. Get above target and steady at that higher BG for a bit. Now take an amount of insulin that will safely get you back near range. Wait about 4 hours with super chill lifestyle. Don’t exercise, don’t eat, don’t fight with your siblings and for God’s sake don’t get on the trampoline. See how much you’ve dropped in BGs. Take the drop in BGs and divide it by the amount of insulin you gave. If you dropped 30 mg/dl with a dose of 0.50 units, then your insulin sensitivity would be 60. Meaning one unit of insulin would be expected to drop your BG by 60 mg/dl.

I cannot stress enough how important ISF is, and how misunderstood as well. Let’s do some ISF myth busting/confirming:

  • Dropping the value of your ISF (say going from 100 mg/dl to 80 mg/dl) will be a good solution to a new Looper who is consistently stuck high. WRONG. This indicates more of a problem with lacking adequate basal rates.
  • Spikes after meals can be dealt with best by changing your ISF. WRONG. Meal spikes should be dealt with by meal entries AFTER you’ve done the work to test your settings as described. Prebolus, adjust carb counts, and adjusting your meal duration (lollipop, taco, pizza icon) are the best way to deal with meals that don’t result in desired outcomes once you’ve adjusted/tested your settings.
  • Illness, medications, and hormones can all change your ISF. TRUE. If you notice that settings that previously worked in Loop after all that great testing…you may have a hormonal female teen. Or a sick kiddo. And yes…you’ll need to adjust some settings for that. (Make a mental note to read my upcoming blog post about the new Override features in Loop…that’s coming up and can help with those situations.)
  • Roller-coastering BGs in Loop can be because ISF is set wrong. TRUE. One of the most common issues is impatience in starting Loop…seeing higher numbers than you are used to (blaming them on Loop not being aggressive enough) and therefore lowering your ISF value thinking that will make Loop correct “better”. WRONG. Lowering your ISF value will make Loop lay on more insulin, but unfortunately, it also works in reverse. Every unit Loop suspends is also undercounted as a result of the artificially low ISF value…leading to a rebound BG. You’ll ride a nice wave of high temp basals followed by suspended basals…and your BGs will reflect that same oscillation.

  • So, if you have tested your basals, tested/calculated your carb ratio, and even tried to take a good swag/test at ISF…yet are roller-coastering? Try raising your ISF value just a bit. If you were at 60, try 65. Keep tweaking slowly and watch for your sweet spot. You’ll find it. Eventually you will find it.

Next Level: Adjust your Meal Entries

Now that your settings are nice and solid…we have a really good place to adjust from. (Really…make sure that you did the work in the steps above. Getting some decent understanding of your fundamental settings will help more complex meal boluses go much better.)

You’re probably wondering right about now “So, I’ve done all that work for settings…but I still don’t quite understand how I’ll bolus for my meals now.” All those awesome extended boluses and temp basal work that you’d been doing and had nailed? How do you recreate that experience in Loop? Meals that tend to stick around longer than just an initial bolus that you used to extend bolus for?

Now that basal rates, carb ratios, ISF are pretty well known, let’s make note of the meals that you normally might give less upfront and more of the total insulin later instead. Like pizza anyone? Chinese food. Quesadillas. Rice (omg, the rice) and sushi.

If you gave all that insulin upfront, you’d be going low early and high later…not the best outcome. Think of it like a game of tortoise and the hare (rabbit).

A quick carb meal like a fruit snack is a rabbit…it can out-run any insulin. It is super fast digestion and uses all its energy very quickly.

A slow carb meal like pizza and pasta is a tortoise. If you gave all the insulin up-front, you’d go low low within about an hour of eating and then be high high for hours later.

As a Juiceboxer and Surfer on a tortoise meal, you’ve gotten accustomed to some insulin upfront but using an extended bolus or temp basal to make sure insulin is still around to deal with those late BG climbs. Loop has a way of dealing with those meals too…it’s actually a pizza icon. Literally. You tell it the total grams of carbs for that meal (remember to add “equivalent carbs” to your total meal carb count if there are fats and proteins) and tap a pizza icon…that is equivalent to telling Loop that you are extending a bolus.

Let’s look at an example, Anna has a bowl of pasta for dinner.

If Anna and Loop had bolused based on carb ratios alone, her bolus would have been 6.25 units. Her carb ratio is 8, meal is 50 grams.  50g/8 = 6.25 units.

But, Loop only recommended 4.85 units up-front. Why? Because I told it this was the kind of meal that was a tortoise. It was going to be sneaking slow at first and stick around for a long time. Loop gave an appropriate amount up-front and then waited like a stealth ninja to deliver the rest when the danger of low BGs had passed.

How did that meal go then? Let’s show that in pictures

And how did that meal do hours later while I slept? Pretty freaking fabulous. As that slow tortoise tried to get to the finish line, Loop kept pushing back. Hours later, Loop had won the war and the tortoise had run out of steam (pasta had finished digesting).

Similarities with Juicebox and Sugar Surfing

All of this reading and do you see it now? Where Loop and the other methods are similar with regards to “nailing” a meal?

They all still involve a bit of learning when encountering a new food. And that is a-ok. Getting friendly with a new meal? Here’s the differences in behavior between the two:

  • With Loop: You adjust how you enter carbs to fine tune Loop’s insulin deliveries.
  • With Juicebox or Sugar Surfing: You adjust insulin in reaction to observed BGs. Carb entries are relatively unimportant.

So…in practice these are actually kind of similar, just different where you are adjusting. If you have a meal, you can learn from it in both systems. If you have a meal in Loop and end up stuck on a high later…add some carbs to the meal entry next time (or even edit the carbs mid-meal to help Loop know that perhaps you didn’t quite guesstimate carbs right) and use a longer food icon (move from taco to pizza). How many carbs to add? If your settings homework was done, the Insulin Counteraction Effects screen in Loop can help you TREMENDOUSLY to dial in those meal entries. Loop will help you see just where your carbs impacted you and help you for the next time to estimate total carbs to enter and how long.

If you really want to fine tune, you can do mixed meal carb entries…give a portion of the total carbs to the tortoise and a portion of the total carbs to the rabbit. My teen doesn’t usually go through that much effort, but that’s ok for us. Could we get slightly better results if we were super diligent about telling Loop the exact mix of a meal? Yes…but we’ve decided the effort’s not worth it overall after 2.5 years of Looping…but I’m glad the option is easy to access for those who would want to.

Read the Docs

Don’t forget to read Looptips.org. There are loads of helpful tips about how to deal with situations in Looping. How to do these settings tests. And for Juiceboxers and Surfers especially, work on converting those old bolus techniques into settings and carb techniques. Identify the results-oriented tools you’ve been using (insulin dosing) and back those into settings understandings.

And then recognize that you’ve been doing the work of a closed-loop system for awhile now. Kudos to you. If you can take the time to dial in the settings as described above, you will have successfully developed the tools to let Loop know the needed info so that Loop can take that closed-loop job for you. It can babysit the reactions to BGs now.


Loop for you?

Loop is on the cusp of releasing support for Omnipod users.

This is a monumental change to the tools available to the type 1 diabetes community. BUT, it has also created a vortex of emotions and shoe-box-speeches that I struggle with in a more broad sense. How can I make sure that a HUGE influx of new users come to this system well-prepared and educated? I can’t hold each person’s hand through this process one-by-one. So I need your help. If you are considering Loop, or have a friend considering Loop…read and share this post.

Many people have excluded themselves from DIY looping because they assume Loop requires some difficult technical knowledge about computers or software. (Spoiler alert: It doesn’t.) In November 2016, I made it my personal mission to make Loop-use inclusive of everyone, tech geeks to busy parents to grandparents to college students, when I started working on instructions and documentation of the Loop app. My goal was that anyone who was willing to read some simple instructions, aided by pictures, could build and use Loop successfully.

My work seems to have been successful as there are now many, many people using Loop who likely would have never tried otherwise. I’m delighted when I hear feedback that tells me the documents I’ve written were easy to follow and helped.

What slays me is when it is obvious that people ONLY read the parts that deal with building Loop.  They never read the parts about USING Loop.

Instead, they built the app…walked away from all the awesome other information online about USING Loop…and assumed they’d just be fine.

It bears repeating the obvious: This app is automating insulin delivery to you (or your kid). That simple fact alone should make you want to read all about how to use it.

So as all these people are out there excited for when the Omnipod Loop code will be released…this is a great time to remind you about the importance of learning all about Loop beyond the build. Loop doesn’t behave like your old pumping life did. A few examples:

  • Did you know that you can’t set your own temp basal on Loop?
  • Did you know that you can’t set your own extended bolus on Loop?
  • Did you know that if your settings (scheduled basal, carb ratio, etc) need adjusting (illness, hormones, etc), Loop won’t do that for you?
  • Do you know what a reasonable maximum basal rate might be?
  • Do you know what might cause a roller coaster of BGs on Loop?
  • Do you know how you are going to share data with your Endo if you aren’t using your PDM anymore?

If you read those statements and thought “WHAT? Then how does it work? What am I supposed to do now?” then head on over to LoopDocs.org and LoopTips.org. Those two websites have a ridiculous amount of helpful information for you to get familiar with the new Loop life you’d be living.

And after your Loop is up and running…remember those resources will be there still for you when you have new situations and questions. No shame in going back to the docs when in doubt.


What’s your “why”?

I need your help, please.  I’d like to hear your “Why I restart my dexcom?” stories.  Can you please read this post and let me know your why?  Do you have examples to share?  I’m sharing mine.

This request for input is partly motivated by this article in Diatribe where they state:

“This [restart topic] is a complicated issue, since many people pay a lot of money for CGM and the ability to extend a single sensor’s wear time – e.g. to 14 days – makes CGM more affordable…We’d like to see an end to complaints about not being able to “extend” the system – or even whether it’s possible. It’s been decided, and we believe this decision is in the best interests of people with diabetes, the system, and providers.”

Here’s my problem with that…it’s not about money by and large.  Let’s expand our vocabulary as a community and take this as an opportunity to think about what CGM *really* means for us.  An expanded conversation may just help educate the CGM manufacturers and insurance industry to make changes so that restarting is indeed a thing of the past…WITHOUT sacrificing what we are really after…LESS downtime, LESS hassle, MORE reliability for our MEDICALLY NECESSARY equipment.

I’m a bit tired of the “restart conversation” being boiled down to money so very often.  Yes, money is a factor.  But…for so many of us…money is not the primary driver.  The real driver is about redundancy, dependability, and flexibility in our medically necessary equipment.

Medically necessary or Helpful tool?

Do you feel like your insurance understands how valuable this CGM is to you?  Or dexcom?  Do they understand?  Framed another way, do you think that insurance/dexcom kind of view your CGM as a “helpful tool” vs a “medically necessary” device?

For many in the community, we view this as a medically necessary device whereas insurance/dexcom view this as a helpful tool.  There’s a BIG schism between us and our supplies as a result.

Insurance approves, and dexcom builds, a CGM system that has gaps in my BG coverage.

  • A mandatory minimum 2-hour window without BGs.
  • Prescribed supply chain that has zero tolerance for inevitable equipment failure or travel.
  • No opportunities to take steps to provide a backup plan for truly CONTINUOUS glucose monitoring.

Why is that supply chain setup like that?  Because CGM is still widely viewed by outsiders as a “helpful tool”.  But, those of us on the inside of managing this disease who choose to use a CGM…it’s actually a medically necessary device.  CGM has shaped how we live our lives, and allowed us to live a life more closely mirroring those of our non-pancreas-challenged friends.  That’s not selfish or asking for too much…it’s actually also a good business decision for the medical community.  Win-win.

With the approval of the G6 for no-finger-check management decisions, this means more people are relying on the device for their medical safety.  Blood glucose meters are left behind more often.  BGs are checked quickly on a phone or watch so that other life decisions can be made more quickly.  Travel has become a bit less intimidating.

So yeah…it’s medically necessary.  It allows my daughter to not have to restrict her life or “take the blame” for having a disease…but rather she can be protected medically as she leads a normal life.  She can do the things that otherwise might be so difficult to traditionally manage BGs during (trampoline parks, long backpacking trips, stressful job situations) without having to put herself into medically-dangerous territory.

The Diabetes Burden

Living with diabetes brings all sorts of burdens…not the least of which is managing all the situations that you need to plan for backups.  Backups upon backups upon backups.  Because you can’t be at the beach one afternoon and tell diabetes “hey, I forgot to pack the glucagon this one time, so give me a hall pass today, ok?”  I wish it worked like that.  And you know what?  A person with diabetes shouldn’t have to be any more perfect than their non-diabetic friends.  They forget things too…it’s just not life-threatening when they do.  And a person with diabetes shouldn’t be blamed when things go wrong with all the spinning plates they manage…it’s just life that a plate falls once in awhile.

Let’s expand our thinking…in an ideal world, how could your diabetes burden be lifted if insurance/dexcom viewed the CGM as medically necessary?  Prescriptions could be written and filled so that you could:

  • have an extra sensor/transmitter in your work desk…no longer need to leave work because your CGM failed and you don’t have enough supplies to keep duplicates at home/office.
  • travel for an extended period without wondering how you are going to get your supplies while in the jungles of Costa Rica, for example.
  • have access to enough supplies that you could wear overlapping sensors to provide redundancy and overlap.

What’s your “Why”?

To end the “restart discussion”, we need to open the discussion about WHY we restart sensors.  It is not about money.  We do our community a disservice when our articles only discuss this as a factor.

It’s about being able to depend on a medically necessary device.  And a medically necessary device needs to have a robust backup plan and solid supply chain.

My “why” is because I am filling that gap.  Exactly 30-day supply leaves no room for error.  It doesn’t have to be like that.  There are things that the industry can do, if they can shift their thinking away from this restart issue being about money.  It’s about a medically necessary device in my daughter’s life and I need it to have backup and continuous operation.

As I sit on the phone now with Dexcom because our G6 sensor has failed (bent wire when it was inserted last night) and I have no G6 sensors on the shelf (it was the third in our box of 3 for the month…next one doesn’t ship out for 2 days)…I’m reminded of my why.  I’m filling a gap that doesn’t have to be there.  I should’ve been able to pull this sensor hours and hours ago when I knew it was bad and simply replaced it.  Instead, we’ve absorbed the burden that doesn’t need to be there simply because I have no backup on a shelf and I’d hoped a miracle recovery would’ve been possible.  We can do better than simply calling this a “money” issue.  It’s our medically necessary device that allows her to live a normal life safely. Today will be a medical burden and it didn’t have to be that way.  A small shift in thinking could make this go away and I wouldn’t ever have to write another post about restarting sensors.


Please share your why in the comments.  Please…I’d like to have this conversation.  It’s important.

Fiasp Day 17 update

Our Fiasp experience started October 11th.  Here’s what I was expecting:

  • increased insulin resistance
  • fast insulin

Optimistically, we gave our first Fiasp bolus.  Full of excitement.


After 24 hours, here’s how I summarized our experiences:


1. If Anna started to rise with pretty significant IOB, I adjusted basals up. The last adjustment was leveling out beautiful, then started to climb for three consecutive readings about +3 or +4 each time, but the important part is that it was happening with 1.8 u IOB. That means she was really short on basals since it was nearly 3 hours after she had last eaten.

2. Also, she climbed more than 150 mg/dl from eating one single uncooked spaghetti noodle. Do I really think that was all noodle? NOPE. Definitely another sign that basals were too low. Shouldn’t be spiking that bad from small food.

3. Only one adjustment was to lower basals…when she had dropped significantly and had negative IOB. That was the adjustment right before the steady line at night. I had apparently gone too far with the earlier basal increase.

4. We prebolused the first meal by about 8 minutes I’d say. A peanut butter sandwich that she overcounted carbs on. That’s the only low we corrected on this graph. (Fiasp rebounds quickly from inadequate basals). Tonight’s sandwich is the same meal, but bolused with a stronger carb ratio, and no prebolus. Looking better.

In short, an awful lot more insulin needed almost right away. Like A LOT more. BUT, the no prebolus thing is real. And Loop’s fiasp curve is working better and better as I get my settings better fleshed out.

We had a couple good days, but then things started to get a little worse for wear around day 4.  We were having an awful time of:

  • volatile BGs, more lows to treat/more highs to stare at and wonder
  • fast insulin
  • insulin sensitivity
  • frustration with looping
  • distrust of looping (both Loop and OpenAPS, I tried both)

Our days just got progressively worse.


Then on the evening of October 18th, we just had a lot of stubborn lows and I was sick of spending so much time on diabetes again.  We were treating a lot of lows in advance on those graphs.  I had a choice between throwing the Fiasp into the trash (considered mailing it to a friend but wondered if that would even be considered “nice”) or *gasp* suck it up and go back-to-basics.  I opted for back-to-basics…aka open loop test all our settings.


It didn’t take long to find my first problem on open loop.  Notice on the screenshot above, the low near midnight after a manual correction?  WOW, that correction brought her down over twice as much as I’d expected and I needed to treat a low.  Basals were too strong and I suspected my ISF was way off, too.  I lowered basals as I treated the low but didn’t adjust ISF at the time (after all, I was still open looping so ISF wasn’t actively being used other than by my brain if I wanted to do a correction).

For two days, I opened my loop so that I was in control.  I tested basals, tested ISF, tested carb ratios, watched my IOB, and watched Loop predictions during all of this.  Things got better pretty fast.  After a day and a half, things had smoothed out quite a bit with a lot of adjustments.


The screenshot above shows a few things I learned.  That dip at middle near noon…Anna’s PE class.  She is very sensitive to her lunch bolus since PE comes right after.  We are still working on that.  It’s not a fiasp issue, per se.

But, the more subtle observation?  See the Loop prediction?  Loop was predicting that she would start coming back up around 12:30pm.  But instead, she was still heading down.  This started me wondering if either my carb ratio was still too strong, and/or if I needed to maybe shorten our default carb absorption times.

It became pretty obvious that my carb ratio was still too strong in the next few meals.


Basically after two days of open loop use, I learned that my basals had been too high, my ISF had been too weak, my default carb absorption times needed to be lowered, and my carb ratio was too strong.

The odd part to me was that you’d think that with all those indicating that I would need less insulin…we would’ve only been battling lows while closed looping the week before.  But, we weren’t.  We were fighting lows and highs.  I think that all the suspends to keep us from going low were leading to some strange rebounds with fiasp.  It was really hard to see through all the looping noise to figure it out though.

In the end our average numbers by comparison have ended up as:

  • Novolog: ISF = 40, Basal = 1.0, Carb ratio = 7.5
  • Fiasp: ISF = 58, Basal = 0.85, Carb ratio = 10.5

Our settings now are working much better.  We closed loop again and are happily looping on Loop.


Other than the standard things we learned on open loop regarding basals, ISF, and carb ratio…we also decided to shorten the 1.5x carb absorption multiplier that is default in dynamic carb absorption.  Basically, we shortened our default carb absorption buttons to 1, 2, and 3 hours for lollipop, taco, and pizza.  Other than that we are using the standard Loop settings.

Why did I adjust the default carb times?  Because of the way Loop calculates bolus recommendations, the quicker peak time of Fiasp will predict an early low after eating meals compared to a similar meal with Novolog.  So, even if everything else is equal, a meal bolused with Fiasp will tend to get less of a bolus typically for an average meal than a bolus with novolog in Loop, and this effect gets more pronounced the longer the carb absorption is entered.  Therefore, that 1.5 multiplier will tend to lower the recommended bolus even more.  What we found happening was a smaller upfront bolus would be followed by a high temp/high BG, and then we would crash later as the later carbs (from the rest of the 1.5 multiplier area) wouldn’t be there to support the earlier high temps.  So the upfront and later parts of the meal were being affected by the multiplier. (*screenshot from a pizza meal below and part of this screenshot was also affected by our settings still not being tuned, so take it with a grain of salt.)


On novolog, we never had this issue I suspect because the peak time of novolog was so slow that dynamic carbs had enough time to adjust the predictions before the high temps came on and couldn’t be recovered from.  And we prebolused a lot, so the insulin was pretty active by the time she ate to help prevent spikes.

So, in summary, I’m stoked on Fiasp.  It’s been great now.  BUT, it didn’t behave like others had experienced…so keep your mind open.  Perhaps we will find resistance later, after longer use.  If we do, I’ll be sure to document.  And, if you find yourself slumping into confusion initially with the change from novolog/humalog…don’t be afraid to open loop to get your feeting solidly beneath you again.  A day or two of open looping can save you from wanting to poke eyeballs out.  And, sadly, some meals can still really benefit from a 5-7 min prebolus even on Fiasp.  The really fast carbs are still faster than Fiasp.  Simply announcing those carbs won’t be enough for my teen’s fast digestion.  We are learning which foods need prebolus and for how long…but the list is A LOT SHORTER than with novolog (novolog list included just about everything but water and ice).

Side note (because I also love the not-perfect-examples, too): Fiasp still doesn’t save you completely from a really poor carb count and a busy teen.  Example, she ate 20g uncovered just before I picked her up from karate.  I didn’t know that and she was just distracted.  We almost immediately went to In-n-Out where she scarfed a double-double with a HUGE french fries basket.  We were way off on carb counts (originally this graph only had 80g on it because I didn’t know about the previous 20g and I didn’t know she was getting fries, too).  We adjusted carbs a couple times as I found out about things…and gave the suggested corrections as we adjusted.

But, the recovery from such a bad carb count, no prebolus, and eating 20g without any bolus for that portion…really quite fantastic and quick.  3 hours after that meal was eaten we are recovered…and I don’t think we would look like this with novolog.


(As with all things, don’t take my word as gospel on Fiasp.  I’m still experimenting. YDMV.)