Enhancing Glucose Control Through Exercise

Before we go into more detail about how exercise enhances glucose control, it is important to mention that the Centers for Disease Control and Prevention (CDC) and the American College of Sports Medicine (ACSM) recommend 30 minutes of moderate-intensity exercise on most or all days of the week. You can split up the 30 minutes of exercise into three 10-minute sessions per day and receive similar benefits in controlling glucose.

To better understand the effects of exercise on glucose control, we need to separate this process into two parts: the acute effects of exercise (what happens when you've exercising) and the chronic effects of exercise (what happens over time). The acute effects of exercise are directly related to the increased rate of muscle glucose restoration (how much a muscle feeds itself from glucose in the bloodstream). We call this muscle glycogen repletion (glycogen is the storage form of glucose). When a muscle is exercising, it uses the glucose that is stored within it; when glucose is depleted, the muscle restores this loss by taking glucose out of the blood. This in turn reduces the blood glucose level, enhancing glucose control at the time of exercise. The chronic effects of exercise are related to the increase in metabolically active muscle. More exercise over time produces more active muscles, which in turn use more glucose, keeping the blood level in control. However, if you stop exercising, in as few as two days these effects can be reversed.

Insulin plays a key role in controlling glucose transport into the cells. When you exercise, your cells become more sensitive to insulin and glucose is transported into the cells at a faster rate. This reduces the blood glucose level. The insulin sensitivity and the increased metabolic rate of exercise together help control glucose levels. You will see these improvements in your glucose metabolism typically within one week of starting aerobic activities. Then you can see improvements in the glycosylated hemoglobin, or hemoglobin A1C (which shows the status of your glucose levels over a three-month period). People with type 1 diabetes experience positive effects from exercise similar to those experienced by people with type 2 diabetes. However, in those with type 1 diabetes, the changes are entirely dependent on insulin doses and diets.

Other effects from exercise can help enhance glucose metabolism. For instance, if we looked under the microscope at a muscle that has not been exercising and compared that muscle to one that has been exercising, we see that there is an increase in the number of very small vessels (called capillaries) in the exercising muscle. With an increase in the capillary density, more blood flow to active muscle increases the efficiency of glucose metabolism.

In addition, weight loss is a common result of exercise in a person with type 2 diabetes and not as common in a person with type 1 diabetes. Typically weight loss will improve the overall health of someone with type 2 diabetes and will decrease the need for insulin in those who are dependent on it.