Diabetes: The Highs and Lows of Exercise
By Dr. Alex Dreyer, Naturopathic family doctor
We all know that exercise is good for us, both mentally and physically. Those living with diabetes have most likely witnessed firsthand the powerful effect of exercise on our blood sugars. Ever since I was diagnosed with Type I as a little girl, I was told how exercise can lower our blood sugar and it was important to always have a snack on hand when exercising in case I went low. You can imagine my surprise after particularly long, intense soccer games when I would test my blood sugar afterwards and I somehow would have shot up from 100 to 250. What the *%&$?!?!
I can remember my frustration after waking up at 6 a.m. for Cross Fit, without having eating anything, and my blood sugar rose from 130 to 360 over the course of an hour’s workout without any food. This makes no sense!
Especially considering I rode my bike for two hours the other day and watched my blood sugar PLUMMET over the course of my ride, so why do things like soccer and Cross Fit have the opposite effect?!
As it turns out, not all exercise is created equal, especially when it comes to your blood sugar.
Not all exercise is created equal
Muscles consist of long fibers that contract when performing work; these contractions require high-energy compounds either derived from glucose or fatty acids. There are two forms of exercise:
· Aerobic (with oxygen)
· Anaerobic (without oxygen)
Aerobic exercise, which includes moderate jogging, cycling, swimming, walking, tennis, etc., derives high-energy compounds from small amounts of glucose and large amounts of oxygen. When muscles exercise aerobically, they don’t increase much in mass and therefore don’t require as much glucose for energy.
On the other hand, anaerobic exercise (weightlifting, intense running, intense swimming, intense cycling, pull ups, etc.) demands energy at a very rapid rate and must be able to produce high-energy compounds faster than the heart can pump blood to deliver oxygen. This form of exercise deprives the muscle of oxygen, which tires out the muscle much more quickly and therefore requires 19x as much glucose to do the same amount of work as aerobic exercise.
So, what does this mean for those with diabetes?
We need a way for the insulin to get into our muscle cells for the muscles to use this fuel. This is done by glucose transporters (GLUT4 receptors). Physical exertion actually increases the number and mobilization of glucose transporters in muscle cells. This is why you will see your blood sugar decrease after prolonged, mild aerobic exercise: glucose is being sucked out of your blood and into your muscles more quickly.
However, moderate to strenuous anaerobic exercise needs more fuel and therefore causes an immediate release of stress hormones (such as epinephrine and cortisol), which tell the liver and muscles to return glucose to the bloodstream by converting stored glycogen into glucose to be used as fuel.
In a non-diabetic person, the pancreas releases a little bit of stored insulin to keep blood sugars from rising, but as we know, this does not happen in those living with diabetes, and thus blood sugar rises.
Therefore, brief strenuous exercise can raise blood sugar while prolonged mild exercise can lower it.
Both types of exercise (aerobic and anaerobic) are beneficial to your heart, lungs, muscle mass, metabolism, mental health and confidence. You should incorporate both types of exercise into your workout regimen.
Get support managing your exercise and blood sugars
As an acupuncturist and licensed naturopathic family doctor with an interest in functional medicine, I aim to establish proper foundations of health utilizing nutrition, exercise, sleep and stress-reduction, as well as herbs, supplements and acupuncture for more targeted care. If you need guidance surrounding designing an exercise program tailored to you, or need support surrounding managing your blood sugars during and/or after exercise, I encourage you to make an appointment with me so we can come up with the best individualized plan for you.
About Dr. Alex Dreyer, Naturopathic and functional medicine family doctor
Dr. Alex Dreyer is a naturopathic and functional medicine family doctor at Natural Health Center in Anchorage. She has advanced training and clinical interests in cardiovascular disease, diabetes and gastroenterology. She considers herself a primary care doctor and enjoys working with all ages and a wide variety of health conditions. Learn more about Dr. Dreyer or contact Natural Health Center to schedule an appointment.
“Chapter 14: Using Exercise to Enhance Insulin Sensitivity and Slow Aging.” Dr. Bernstein's Diabetes Solution: The Complete Guide to Achieving Normal Blood Sugars, by Richard K. Bernstein, Little, Brown, 2011, pp. 221-247.
Exercise and Diabetes: a Clinician's Guide to Prescribing Physical Activity, by Sheri Colberg, American Diabetes Association, 2013.