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Integrated Diabetes Services

How to prevent workout hypoglycemia


glucagonThey say laughter is the best medicine. If that is true, then physical activity must be a very close second. Physical activity has been shown to reduce risks for everything from heart disease and stroke to depression and Type 2 diabetes! The unfortunate irony is that for people with diabetes using insulin, physical activity can also lead to one of our most dangerous short term risks, hypoglycemia.

Hypoglycemia, or low blood sugar, can cause physical symptoms including; anxiety, loss of coordination and mental clarity, rapid heartbeat, shaking, loss of consciousness, and seizure.

In a non diabetic person blood sugar is regulated by insulin and glucagon from the pancreas. Glucagon is a hormone produced in the pancreas that signals the liver to release stored glucose in times of low blood sugar or when intense mental or physical activity increases glucose demands of the body. Insulin lowers blood sugar and the presence of insulin inhibits the glucagon release to the liver to release additional sugar into the blood stream (after all, why would your body send out insulin to lower blood sugar, and glucagon to raise it at the same time?). 

Unfortunately, in a person with diabetes, the presence of insulin taken by infusion, injection or inhalation means that even though our blood sugar may be low, and demands for glucose are high, glucagon is not released, and the liver does nothing about the situation. (Come ON Glucagon, you had ONE job! But remember, glucagon is not stimulated by low blood sugar, but by the absence of insulin, and we are putting insulin into our bodies. So our glucagon just sits there watching the insulin lower the blood sugar.) During exercise,  insulin keeps driving us lower, as our bodies are burning up what little glucose there is. This spells potential disaster level hypoglycemia

There are three options to avoid these episodes of hypoglycemia:

  1. Avoid exercise entirely. However, this is simply not a viable option. Physical activity has far too many benefits to eliminate this from our lives! Sadly for many years this was what people with diabetes were told, that they could not play sports or work out. Even ore sadly many people still avoid physical activity due to the fear of low blood sugar symptoms experienced in the past. Fortunately improved blood sugar monitoring and self management skills now make it safe for people with diabetes to be physically active safely, even in the top levels of athletic performance.

2. Increase the amount of glucose available to our bodies by consuming additional glucose before and during physical activity. If you know you are going to likely experience a drop in blood sugar during an activity it is wise to consume fast acting carbohydrates just prior to beginning the activity and throughout. The problem here is that we often consume too much carbohydrate, or experience a rapid rise in blood sugar. This is a sacrifice of blood sugar management targets and also hampers our body’s performance when we need it at its best. Not to mention that many of us are getting active in an effort to lose weight. There is nothing quite as discouraging as seeing that you burned 400 calories on your fitbit, only to find that you drank 200 calories in juice to keep your blood sugar from going low during the work out!

3. Reduce the amount of insulin on board during the workout. This can be done by reducing, or even eliminating, a pre-workout corrective or meal bolus, or by reducing basal insulin levels ahead of the workout. Unfortunately, reducing basal insulin can be challenging for people on multiple daily injections and long acting insulin. Even for insulin pump users this reduction may be too little, or too late to prevent hypoglycemia entirely.

Most people with diabetes, through trial and error, and close blood glucose monitoring are able to find a combination of carbohydrate intake and insulin reduction that can allow them to be physically active safely and at the level of their choosing.

“But what about glucagon?” one might ask.  Why not have glucagon do its job? We typically think of glucagon in diabetes as a life saving measure injected, in large doses, intramuscularly by someone else when we have reached a point of being unable to treat a low ourselves. In a recent study glucagon was injected in “minidoses” just before exercise to study whether this treatment would be a means of preventing hypoglycemia during exercise. “When initiated just before exercise, minidose glucagon is more effective than basal rate insulin reduction for reducing exercise-induced hypoglycemia and may result in less post intervention hyperglycemia than ingestion of carbohydrate,” said Michael Rickels, MD, from the University of Pennsylvania, Philadelphia, who presented the results at the European Association for the Study of Diabetes (EASD) 2017 Annual Meeting.

In this study subjects went through 4 rounds of exercise on different days. In each round they exercised the same way, for the same amount of time, at the same time of day, and had the same meal following. They were monitored with a Continuous Glucose Monitor (CGM) until noon the following day. The rounds included one of the following circumstances:

– mini dose glucagon was injected 5 minutes before exercise

-20 grams of glucose tablet was taken prior to exercise and 30 minutes after start

-basal insulin was reduced by 50% at the start of exercise

-control where there was no adjustment made for exercise.

Both the control group and the basal reduction group showed the same number of hypoglycemic episodes. This is to be expected as a reduction in basal insulin would need to be made at least 1-2 hours ahead of the workout and throughout the workout to be expected to reduce hypoglycemia risk.  In neither the glucose intake or glucagon injection round did any participants experience hypoglycemia. An added benefit was that the glucagon injection rounds did not show any post workout hyperglycemia. The glucose tab trials showed 2/3 of participants experienced hyperglycemia and 1/2 of those participants experiencing hyperglycemia in excess of 250mg/dL (13.9mmol/L). Over the night and day following all four trial groups showed no statistically relevant differences.

This is an exciting development as it offers a reliable way to prevent hypoglycemia during exercise without adding unwanted calories or hyperglycemia. So many people with diabetes get frustrated because they are exercising to lose manage their weight, but have to take in additional carbohydrates to prevent hypoglycemia. Though they are still getting the cardiac, psychological and muscle building benefits of the exercise, weight loss is slowed because the workouts become calorie neutral.  With more research into dosing parameters, glucagon before exercise could be a major step forward in improving BMI and blood sugar maintenance at the same time rather than sacrificing one for the other. 

This also points toward the hope of a dual hormone infusion system. This would be a system that pumps not only insulin, but also glucagon to regulate blood sugar more closely to how it would be regulated in a non diabetic person. However it also points out that this kind of dual hormone system would then require the additional titration and management of glucagon dosing as well as insulin dosing.

In the meantime, for assistance working exercise into your diabetes management or improving your blood sugar management through and after exercise, set up an appointment with Integrated Diabetes Services. We can work with you to find where the trouble spots are and how to best use the tools of carbohydrate intake and insulin reduction strategies to integrate and maximize your physical activity and performance into your overall management and wellness plan.

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