Run of the Raging Blood Sugars

What do you do when your blood sugars don’t behave and there’s no plausible reason why, and all you want to do is run?

I don’t know about you, but I sure as heck run.

At least, that’s what I did this weekend… more on that later 😉

It was one of those T1D mystery kind of runs!

The last few weeks I’ve been nose deep researching the nutritional recommendations for athletes with type-1 diabetes in preparation for a presentation I’ll be giving to a group of sport dietitians.

Honestly, the recommendations make me laugh.

They were predominantly developed using a non-diabetes population, so totally relevant, right (sarcasm) and they were created with perfect-world scenarios where there’s only one, maybe two, mitigating factors affecting blood glucose during physical activity.


Perfect world?

Where, in type-1 diabetes, has there ever been a perfect world?

The recommendations focus mainly on reducing insulin and increasing carbohydrates, which is great because those are the two areas that we can somewhat control.

Some of the key points include:

  • Starting aerobic activity (ie. running, cycling, hiking, rowing, swimming, etc.) with a BG range between 7 to 10 mmol/L to reduce risk of hypoglycemia and minimize negative impact on performance (I’m on board with this one!)
  • Inputting a temporary basal reduction between 50-75% for the duration of the activity, and activating it at least 1 hour prior to exercise
  • Reducing meal bolus’s by 20-60% for exercise longer than 30 minutes that will be started within 90 minutes, or 2-3 hours depending on the author
  • Reducing basal insulin by 50-80%, 60-90 minutes before the start of exercise
  • Consuming 10-20 grams fast-acting carbohydrates if BG is less than 5 mmol/L with low amounts of insulin on board prior to starting activity, or 15-30 g with high insulin on board.

The remaining recommendations are pretty much the same as those for non-diabetes endurance athletes (ie. consuming 30-60 grams/hour carbohydrates for exercise lasting 1-2.5 hours).

Looking at those recommendations, and comparing them to how my body tends to react prior to exercise and during exercise, I can shoot so many of them down.

If I were to give myself a bolus reduction and a basal reduction that far in advance of starting a run, my BG would shoot through the roof. And if I only took in carbs when my BG was less than 5 mmol/L, I’d be stopped mid run dealing with a low. Normally, I consume about 10-20 g carbs for anything below 7 mmol/L at the start of aerobic exercise.

While these recommendations may work for some, they sure as heck wouldn’t work for me.


Because this disease is individualized and specific to the person it’s attached to – it’s not standardized!

BG ridiculousness
Case in point: Saturday’s Run – full of BG ridiculousness!

My run on Saturday is a perfect example of how ridiculously unpredictable this disease can be.

Consistently my blood sugars run on the lower end over night, generally between 3.5-4.5 mmol/L and then have a modest uprising in the morning. Friday night before bed, they were at 5.1 mmol/L.

I almost ate 2 dried apricots to mitigate an overnight low, but decided to wait and see instead.

Good thing.

I woke up at 2 a.m. and they were 10.1 mmol/L with an angled arrow up.

I did not eat anything out of the ordinary for dinner Friday night– nothing with high fat, like pizza, that would delay a glucose rebound.

I didn’t have any incidence of low blood sugars from 10 p.m. (when I previously checked) to 2 a.m.

Yet, here I was with my blood sugars giving me the big fat middle finger.


I gave myself a correction dose and when I woke up at 5:30, they were 6.5 mmol/L.

I had my normal pre-run/everyday breakfast of oatmeal, which usually pops my blood sugars up about 3 mmol/L within the first hour, and starts to reduce by hour 2.

Not Saturday, though. They shot up to 13.7 mmol/L and showed no signs of coming down.

To mitigate a further increase, I headed out for my run a half hour earlier than anticipated. I still gave myself a 50% basal reduction because typically my blood sugars slide fast during runs.

But Saturday was anything but typical.

I checked my BG 10 minutes into the run and they were up to 16.1 mmol/L!

Are you freaking kidding me? What the bloody hell?

I removed the basal reduction, gave a small corrective dose, and kept going, checking my BG every 20 minutes or so. They did start to come down, but sloooooowly. There were times when it said 10.1, angled arrow down, or 7.5 ,straight double arrows down. I thought of putting in another basal reduction when I saw the double arrows, but decided against it given how unusual my blood sugars had been that morning.

The run in total was 10 km. I ran it at a slightly slower pace than usual; the highs had me feeling like I was in the last 10 km of a full, high heat, hilly marathon. There was no basal reduction. And still, my blood sugars had only reduced to 7.5 mmol/L.

My pod was fine. I’m not going through menstruation. I don’t believe stress was a factor.

Honestly, it was just one of those T1D mysteries.

Blog-Sport & BG
I know I showed this previously, but it’s a good reminder of the many factors we face trying to manage our blood glucose in this world of sport with type-1 diabetes

And it’s because of these reasons (and others) that healthcare needs to tailor their recommendations and strategies to the needs of the individual athlete. Use these recommendations as a starting point, fine, but do not be beholden to them. Instead, work with the athlete!

And there you have it friends; you pretty much just got a sneak peak into the recommendations of my presentation 😉

1. Riddell, M., Gallen, I., Smart, C., Taplin, C., Adolfsson, P., Lumb, A. … Laffel, L. (2017). Exercise management in type 1 diabetes: a consensus statement. Lancet Diabetes Endocrinol 5, 377-90. doi:

2. Murillo, S., Brugnara, L., del Campo, E., Yagüe, I., Duenas, B., & Novials, A. (2015). Carbohydrate management in athletes with type 1 diabetes in a 10 km run competition. Int J Sports Med. 36, 853-857. doi: http://dx/

3. Devadoss, M., Kennedy, L., & Herbold, N. (2011). Endurance athletes and type 1 diabetes. The Diabetes Educator. 37(2), 193-207doi: 10.1177/0145721710395782

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