Diabetes Forecast

Too Much Exercise?

I have type 2 diabetes, and my A1Cs are usually around 6.2. I recently started exercising more. At first, my blood glucose was low all day. But now, with the same amount of food, meds, etc., my A1C is 6.4. I’m in better shape, but how can I get my numbers lower? Paula Tucker, Tallmadge, Ohio

Christy L. Parkin, MSN, RN, CDE, responds:

You can think of exercise as a great blood glucose–lowering drug—most of the time. In some cases, blood glucose can temporarily increase with exercise. But the healthful effects of exercise are much longer lasting—and worth the effort.

What to Know:

When exercising, the body needs extra energy (in the form of glucose) for the muscles. For short bursts, such as a quick run across the street, the muscles and liver release stores of glucose for fuel. With continued moderate exercising, though, your muscles take up glucose at almost 20 times the normal rate. This lowers blood glucose levels.

However, if not enough insulin is present (beginning at blood glucose levels of 250 to 300 mg/dl), exercise can result in a rise in blood glucose. In addition, prolonged or strenuous exercise can cause your body to produce adrenaline and other hormones that can cause your blood glucose to rise temporarily.

Possible Solutions:

Seeing how you respond to exercise involves trial and error. Some people report blood glucose spikes with morning exercise, but not in the evening. Because blood glucose often rises at first after exercise, consider waiting at least an hour to check your blood glucose to give your body a chance to recover and settle down after exercise.


Although your A1C level went up slightly, the rise was within normal levels of lab variations. Congratulate yourself on your good control and on being in better shape, and continue to exercise. Longer periods of moderate exercise may help lower your numbers to target as you use your body's insulin more efficiently; if not, the progressive nature of type 2 diabetes may require medication adjustments.



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