Exercise and fitness with T1DM
Exercise and fitness training are good for everybody, including people with T1DM. But in addition to the demands of training, type ones must constantly monitor blood sugar levels to prevent deep lows and excessive highs.
T1DM does not place impossible barriers in the path of athletic excellence. Ultra-runner Missy Foy, pro-cyclist Phil Southerland, pro basketball player Adam Morrison, and soccer pro Par Zetterberg are all elite athletes with type 1 diabetes.
Not so many years ago, they would probably have been discouraged from pursuing a demanding career in pro sports. It would have been considered way to difficult to maintain healthy blood sugar levels while training at elite levels.
Ultra marathon runner Missy Foy explains,
Doctors thought it would be too difficult, too stressful, to balance insulin and the intensity of training.
All that has changed. Dr. Larry Deeb, president of medicine and science at the American Diabetes Association, says,
I want kids with diabetes to be empowered to take care of themselves and to know and believe that there are no impediments before them. If patients want to run a marathon, I would encourage them.
Blood sugar management
User friendly blood sugar meters and small, convenient insulin pumps have made it much easier to be an elite athlete with T1DM. But there's still the need to keep an eagle eye on blood glucose and insulin levels.
As pro cyclist Phil Southerland explains,
The tough part is, if we have too much insulin on board before the race, we’ll bonk immediately. If our blood sugar is too high we won’t perform at our best, and if it’s too low we won’t perform at all.
Southerland checks his blood sugar 18 to 25 times a day. He says,
We are the C.E.O.’s of our own bodies and we don’t get a break from them.
Regular routines and attention to detail are essential to success. David Weingard, an Ironman competitor, says,
I figured out what it's like to go in the pool at exactly the time the race would start, to test myself during the swim, then to come out and see how much insulin I needed to take. I learned what my routine would be every single hour.
Glucose and insulin work in tandem in the body, so it's not easy to talk about one without mentioning the other. But it's helpful to treat them separately and explain what each one does in the body during exercise.
Usually when talking about diabetes, it's all about glucose making its way from food into the bloodstream.
But glucose is also found in muscles, where it is stored as glycogen ready for use as energy.
When you start to exercise, your body uses the glucose stored in your muscles and liver. As these stores runs low, your body uses glucose from your blood, which causes a drop in blood glucose.
After exercise, the body replenishes glucose stores in the muscles and liver. This can further lower blood glucose, even hours after you have stopped physical activity.
A person with T1DM who exercises in the evening can become hypoglycemic while they sleep. That's why it's good to monitor blood glucose before and after exercise.
The body absorbs insulin differently from day to day. Add to that the fact that exercise affects insulin absorption by increasing blood flow through the body. This speeds up the time it takes an insulin injection to work.
Injecting into an arm or leg that is directly involved in the exercise speeds up absorption even more.
All this makes it essential to keep monitoring blood glucose levels before, during, and after exercise.
Highs and lows
You might think that exercise is only likely to lead to low blood glucose (hypoglycemia) but it can result in high blood glucose too.
If you exercise vigorously, nerves signal to the liver to release stored glucose, which can result in a rapid rise in blood glucose.
This can occur with moderate exercise too if your insulin levels are low. As a result, ketones can be produced, resulting in ketoacidosis.
During gentle to moderate exercise that doesn't last too long, the opposite is likely to happen: blood sugar will fall during and after exercise, which means a risk of hypoglycemia.
Snack during workout
You might need to eat a snack during exercise. The American Diabetes Association recommends snacks that are low in fat with 15 to 30 grams of carbs.
During very demanding exercise, you might have to snack twice. It's a fine balancing act based on what you ate before exercise, how demanding the workout is, and what your insulin levels are.
It's not recommended to exercise within 1 to 2 hours of taking rapid-acting insulin. The insulin will be peaking, exposing you to the risk of hypoglycemia.
If you think a low blood glucose reaction is on its way, stop exercising at once. Do not take any risks.
Keep some glucose handy in case this happens. If you drink soda or fruit juice, it will provide glucose and much-needed fluids.
By David Hay Jones
(Fact-checking: This information has been double-checked against The American Diabetes Association recommendations in its American Diabetes Association Complete Guide to Diabetes: The Ultimate Home Reference from the Diabetes Experts and Alan L. Rubin's Type 1 Diabetes For Dummies, both of which are excellent resources.) Thanks also to the New York Times.