A Comparison of Diabetic and Non-Diabetic CGM Readings: questionable science at it's finest

CGM's are great.

There's nothing quite as useful as being able to see trends and get alerts if your blood glucose level (bgl) is going low or high. Ask any diabetes doc and they'll tell you that CGM's are a game changer, and ideally something every diabetic would have access to.

As I've become increasingly active on diabetes support servers and groups, there are a couple less-than-good things I've noticed related to CGM's. Most notably, newly-diagnosed diabetics who get a CGM almost immediately often fixate on the numbers and focus really hard on being "in range", i.e. keeping their bgl in a non-diabetic range. Which, when your pancreas isn't working the way it should, is simply not possible.

Something else I've noticed is that "old diabetics", that is, those of us where were diagnosed long before CGM's became available, tend to be much less obsessive about staying in-range at all times, instead focusing on long-term trends. I would argue that this attitude is a result of years of relying on finger sticks to get our bgl readings, and thus not being able to actually see the post-meal spikes or rapid raises or falls caused by food, exercise, and stress. Sure, we care about the numbers, but (anecdotally and based on observations) are more inclined to manage based on how we're feeling first, and the actual number second. 

In short, I would argue that diabetics should be able to manage their disease sans CGM before being given one, if only because the data overload results in some very stressful and unhealthy behavior that can lead to serious mental health struggles.

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Anyways.

I put a Libre on Ev. Part of it was straight up morbid curiosity about how a fully-functional pancreas behaves with the same food (and exercise) that fucks my shit up. And part of it was wanting to force the man who's agreed to spend his life with me (and has for well over a decade) to experience a few days in my life. Or at least, as close as a non-diabetic can get.

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A couple things that I knew but didn't really know until watching Ev's numbers for 9 days....

• Non-diabetics fluctuate throughout the day (yes, even fasting).
• They have some fairly impressive deltas (changes between readings, aka the slope of the line).
• They auto-correct thanks to that handy functioning pancreas, so their spikes and drops are kind of impressive, but less prolonged than the ones us pancreas-impaired folks get.
• Pizza gets everyone (also, it turns out that it takes 6 hours for my body to deal with it).
• Rice, Chinese, and Thai food result in a second spike after the meal, even when you produce insulin.

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We started off trying for a scientific approach - ya know, eating the same thing and doing the same exercise. Because pizza is a Diabetic's nemesis, obviously we started with that. 

The Pizza Experiments: Me on the left, Ev on the right

After pizza (where we learned that Ev has a bit of a spike a couple hours later, but nothing super crazy, and my slow-emptying stomach means I feel the pizza-effects for a solid 6 hours), we moved on to breakfast treats, aka muffins and donuts. This was not at all related to there being donuts in my office.

The Breakfast Experiments: Proof that donuts are bad for me, and muffins make Ev's bg spike

Given my propensity for issues with hypos during runs, we also did a comparison after eating oatmeal (I did my overnight oats mix, and he did regular oatmeal because apparently overnight oats are not his cup of tea).

The Running Experiment: Me on the left, Ev on the right - note the oatmeal spike and drop when the run started

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The pseudo-scientific approach stuck for two days, and then Ev got curious and started eating all sorts of carb heavy things that we normally would only eat sparingly. We discovered a couple things during this adventure. First, Thai food is amazing (duh), but does, in fact, give him a fairly substantial (for a non-diabetic) post-meal spike. Second, the initial spike was dealt with very quickly by his pancreas. Third, there was a second spike that aligns pretty closely with what I've encountered eating similar foods.

You heard it here first: some foods have delayed absorption resulting in multiple blood sugar spikes, regardless of if you're diabetic or not. For the record, this is not actually earth shattering or new information, but it was fun to see it in action with a functioning pancreas to compensate.

The post-food spikes were impressive, as were the post-meal drops... and the post-Thai Food spikes were real.

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All in all, it was a fun little science experiment, if only because it gave him a little insight into the stuff that goes into managing/monitoring your bgl and wearing the hardware every day. 

Ev commented that he found himself checking his bgl a lot (it's kind of addictive, as I can attest to), and adjusting his diet to try and keep his numbers level. 

It's also worth noting that he had a legitimate hypo one night, where the Libre read 58 mg/dL, that his body corrected (yay liver!). 

The highest number he hit was 168 mg/dL after one of his Thai food adventures. In general, his range varied from 75 mg/dL to 150 mg/dL. It's also worth noting that he had an a1c done with some regular blood work 6 months or so ago that came back at 5.1% which is a solidly non-diabetic number.

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When all was said and done, I walked away from this adventure with a bunch of screen-grabs of a non-diabetic that I can (and do) send to people wondering if their totally normal blood sugar response is actually normal. 

I also want the record to reflect that even us broken-pancreas people can do a passable impression of a non-diabetic.... as long as we ignore the difference in target ranges.

I want the record to reflect that, while Ev and his non-diabetic self is capable of 100% time in range, I managed an 82 hour streak in-range and a very passable impression of a non-diabetic. I am a god.

In closing, I was amused when Ev lost his Libre the same way I lost my first Libre: to a climbing rope in a rock gym.