How I handle insulin when running long distances
Marathon prep is getting intense. After an injury that kept me slightly out of the game during the summer, I am finally back on the streets, stacking up miles over miles, fine tuning the aerobic engine and enjoying the sensations that running emanates.
While my weekday runs are relatively shorter - at this stage, I rarely run more than one or one and a half hour in a midweek workout - the weekend’s long runs are getting…long!
And while during a classic 60-90 minutes session the blood glucose and insulin dosages are relatively easy to handle, as workouts surpass the two hours threshold and the intensity increases, managing type 1 diabetes really becomes an art.
How much insulin should I take?
How do I avoid hypoglycemia?
How many carbs while I am out there?
I am still figuring out my best strategies, but my experimentations so far yielded some interesting results that seem to work for me. Here are my two cents.
How much insulin should I take?
I like to run in the early morning whenever possible, and I preferably do that in a faster state. I truly enjoy running on an empty stomach, but that might not be the best strategy for a long run when the goal is to finish it in a good shape - or finish it at all. That’s why before a long session I will typically eat one hour in advance, and with food comes the insulin. But since running will increase my insulin sensitivity, I will need to lower my dose. But lowering the dose means that my blood glucose will inevitably rise…and elevated glucose in the blood is bad!
You see this can be a tricky balance to strike, and it is. But with some math and discipline, one can fix it for the most part. Here is what has worked for me so far:
Food: I will eat a snack that has not too much fiber and some good carbs in it. Typically, a banana or some oats with chia seeds are my go-to solutions (the fat contained in chia seeds help slow down the absorption of glucose). Some toast with jelly and peanut butter is also a big classic.
Insulin: the total amount I will inject is 70% of my normal amount. Out of that, I take 60% at meal time, and 40% before I start running. For instance: if I normally need 10 units for my meal, I will only inject 7. Of those 7, I will take 4 at meal time, and 3 before my run. Why
How do I avoid hypoglycemia while running?
What I have just described is the trick that has allowed me to avoid hypoglycemias while out there melting the asphalt. Since I am taking only 70% of my normal dosage, I am keeping my blood glucose more elevated to start with. And since I am splitting the injections into two parts, I am more in control of the spike. Limiting my injection to 4 units instead of the usual 10 I will almost inevitably see my blood glucose rise quickly after the meal. But then I am injecting the rest of the adjusted amount (3 units, in my example), so that I get out running with slightly elevated blood glucose, but not too much and on the decreasing side.
By doing so, I am actively creating a good blood glucose margin to run without risking a low, while at the same time avoiding extremely high spikes.
The amount of insulin will of course vary depending on several factors, mainly the quality of my sleep the night before and my initial blood glucose, but all my decisions concerning the doses will follow the framework I have described.
How many carbs while I am out there?
While doing the math is great to reduce the inevitable risks that are part of the “running with type 1 diabetes” bundle, there’s always something that we cannot control. And that is where it is important to have some fuel at the ready and practicing eating while running.
Eating while running is important for three reasons:
It will drastically reduce your chances of getting a hypo
It will prevent you from “bonking”, or hitting the infamous “wall” that many endurance athletes fear.
You don’t know how your stomach will react to eating while in motion, and you may have to jump in a bush to evacuate. Starting early during training sessions will teach the body how to handle the situation, and avoid smelly surprises during the big event you’re preparing for.
For my carbs, I will stay within the 30g to 60g per hour, depending on the length and the intensity of the effort. When out for very long runs, I use this formula:
1g of carbohydrates x Bodyweight x Hour of effort.
I weight 65kg, so for each hour I will slam down 65g of carbs. This is important because it will ensure that my energy levels stay up when I get into “unknown territory” - which is, after more than two or three hours on my legs. It will also keep my blood glucose at a level that is optimal for continuing without risks - which is, anything above hypoglycemia.
One thing to consider here.
When the body is out under so much stress (a very long run) it starts releasing cortisol, which can spike blood glucose. One could argue that adding more carbs on already elevated blood glucose levels is bad. That’s absolutely true in general, but this is not your typical day spent sitting on the sofa or at your desk. You’re on the streets, running alone for 2-3-4 hours (or even more!), and in that situation I will not hesitate a second keeping my glucose on the higher end of the spectrum. The last thing I want is to collapse on the street without anyone there for the rescue.
Additionally, when the endurance effort is especially long, eating could “paradoxically” help lower your blood glucose. Think about it: the body is already under stress because it’s been running for so long, and now it doesn’t even have food to restock the energy tank. This is yet another stress factor adding up, contributing to more cortisol circulating in an alarmed organism. So eating could be perceived as a sign of relief by your nervous system, which will start to chill a bit.
A few examples
I understand this whole process can sound very complicated and tangled, so let’s make this big mess a bit more practical with some examples.
Example 1
I have 2.5 hours of zone 2 running on the schedule. I wake up with BG 160, and notice it has been decreasing in the past hours (like: it was at 200 a few hours before). My usual morning bolus is 8 units, but since I am about to go for a long run, I take 70% of that, which is around 5.5 units. Of those, I inject 60% (around 3 units) while I eat my pre-workout snack, and the remaining part (40%, around 2 units) right before going. The total injected is 3+2=5 instead of 5.5: being conservative is good in this case because my BG was already decreasing.
I will also take with me three gels, for a total of circa 160g of carbohydrates. Why? Because I am 65kg, and the formula is 1g carbs x hour of exercise x bodyweight —> 1g carbs x 65 x 2.5= 162.5.
I will eat those once every hour: two should be enough, but I’ll take three just in case I have some low blood sugars, since my blood glucose was already headed downwards.
Example 2
I am about to run 1.5 hours, with some faster sprints in the middle. I know that speed work will tax my glycogen stores more heavily and burn my glucose faster, so better be prepared. my blood glucose is at 110, and has been steady for the past few hours. It’s noon and I would normally need 12 units of bolus. I will go for 8 instead, taking 5 right now at meal time, and the rest in about one hour, right before I start my run. After one hour, I see my glucose levels are at 90, so instead of taking the remaining units I eat a few dates and head outside to hit the streets. I would need one gel with roughly 30 grams of carbs, but I’ll take two because I am close to danger zone (low blood glucose), and I want to avoid unpleasant situations. Always better to return home with blood glucose at 230 rather than collapsing on the street.
Not trivial, I know.
Took me a while to figure all of this out, and I am still right in the middle of the process myself. As exemplified above, sometimes I need to adjust my insulin dosage based on the starting blood glucose levels and the patterns it is following - if I am already in hyperglycemia, I will take a bit more, while if I am on the lower range I will be even more conservative. But that’s a bit of a dance we have to do with diabetes, each time adjusting the tactic to best suit the strategy.
In all this, having stable blood glucose levels most of the time is crucial for success because it will massively reduce the guesswork and all the uncertainty that comes with it. That is why I am a big advocate of the Mastering Diabetes method, which tackles diabetes management with whole food plant based foods that are rich in carbohydrates and low in fats. That’s a recipe for maximum insulin sensitivity, maximum time in range and for defeating insulin resistance. That will ensure you stay in range 80-90% of the time. From there, fixing your dosages will be much, much easier, because your organism will simply use insulin more efficiently.
That’s it. Long bouts of endurance are possible, in total safety, with type 1 diabetes. In this article I offered my current solution for making sure I can run efficiently and without risks, but I am more than curious to hear what you have to say on the topic! How do you go about managing your carbs and insulin intake? What is the biggest problem you face when juggling with all these factors?
I’ll read you in the comments…see you next week!
