The Effects Exercise has on Blood Sugars

This blog post was originally written for theinsulintype.com

Hi everyone! My name is Matt Vande Vegte and I am an online trainer living with Type 1 Diabetes. I want to go over a fun, yet intimidating topic.. exercise and blood sugars. Its an interesting relationship between the two, but I want to demystify the cause and effect that can lead to us shying away from getting our exercise in. I want to show you that it can actually be relatively consistent and predictable with proper planning, documentation, and consistency. While this is something that I coach on in depth through my diabetic health coaching program, this will be more of an overview so that we can keep it short.

Cardio.

Runners, walkers, dancers, any steady state movements really.. These types of exercise typically will lower blood sugars. Most of us have a general knowledge of this, but why does it happen? Essentially, during the first 15 minutes of exercise your body uses sugar from the blood stream and muscle stores to fuel your exercise. Removing sugar from the blood stream = lower sugar in the blood.. easy right? After about 15 minutes, the body begins to use stored sugar from the liver, which has been stored in the form of glycogen (this is the same storage form for your muscles). It is converted from glycogen to glucose so that it can be utilized properly for energy expenditure. Lastly, around the 30 minute marker your body moves to burning fatty acids for fuel. I’ll stay away from the science for now, but in general, it is important to understand that these effects are multiplied when exercising with IOB, or Insulin On Board. If there is less sugar for the insulin to bind to in your blood stream due to activity, and you still have insulin floating around from your last injection, you may need to replenish with a glucose tab or other fast acting sugar.

Guess what else? The exercise induced insulin sensitivity gained from your workout (it’s a good thing) can last 24 or even up to 48 hours! Be extra cautious if you are new to exercise as these effects may take you by surprise. This is where consistency comes into play. If you are consistent with your exercise, you will essentially remain in a state of improved insulin sensitivity! Wearing a CGM such as Dexcom can make this transition much easier (and safer) to get quality sleep after a fun filled active day. The low blood sugar alarms will allow us to rest easy knowing that we have a safeguard in place.

How do we stay safe while running around and having a blast while exercising? Monitor blood sugars, have fast acting sugar nearby (I keep mine in my gym bag AND in my car), and if possible, wait 2-3 hours after your last injection to ensure that you have as little insulin on board as possible. If you wear an insulin pump, you may even be able to find a temporary basal setting that works perfect for you! If not, consider a small snack before you begin to stay steady during your exercise. Start slow if you are new to exercising and document what happens to your blood sugars each time until you start to see patterns. Stay consistent and don’t let diabetes hold you back from living your life!

Resistance Exercise.

This one can be tricky, but the general rule of thumb is that if you are lifting heavy, using H.I.I.T. (High Intensity Interval Training), or other forms of explosive, intense training, you may see a rise in blood sugar levels. Why? So glad you asked! These types of exercises can trigger a release of stress hormones in the body such as cortisol. The resulting high blood sugar can be very disheartening, but don’t let that deter you from staying consistent! The long term benefits of resistance training far outweigh the annoyance of a slight rise in post workout blood sugars. This rise will vary person to person, by the intensity of the exercise, the duration of activity performed, time of day, insulin on board, how hard the wind is blowing.. ok that last one was a joke, but blood sugar levels can fluctuate as a result of many factors, some of which are not your fault. It is for this reason that you should try to avoid getting frustrated with yourself when you see bad numbers, but rather treat them as necessary (either give insulin or have a snack), and continue on with your amazing life.

How do we best prepare for the blood sugar rise associated with resistance training and intense exercises? This answer varies immensely person to person and you may need to consult your doctor for medication adjustments. You may require insulin increases in the form of a temporary basal setting, or even a bolus before or during your workout. I used to have to take insulin at the beginning of my workouts, but have since found a “hack” to stay steady without it.. but this article is already too long so I’ll have to dive into that subject on another day. 😉 It doesn’t matter what type of exercise you decide to go for, and it doesn’t even have to be in the gym. Just get out there! Make sure that you aren’t letting diabetes define who you are or what you do. This is your life and you are a WARRIOR. Keep up the Fight!

You can do this!  Let me know if I can help.

Keep up the Fight,

Matt Vande Vegte, CPT

For a helpful link in understanding what a good blood sugar range is, check out this Diabetes Strong article here: https://diabetesstrong.com/what-are-normal-blood-sugar-levels/