I am 57 years old, and have had type 2 diabetes for three years, and I have been told, read and experienced lower blood sugar readings post moderate to stressful exercise of about 20 minutes duration. I can experience a 30-40 mg/dl [1.7-2.2 mmol/L] drop in blood sugar readings. However, I see questions about increased blood sugar after exercise which you say are normal. Please clarify.

The normal physiologic response to exercise (in the non-diabetic state) will involve a decrease in circulating insulin levels, an increase in glucose use for energy, with a possible decrease in blood sugar levels. The process is a bit more complex than this explanation allows, but the body uses a number of mechanisms to maintain blood sugar in a normal range despite the increased utilization.

The difficulty in diabetes arises related to both the effects of the disease process (insulin resistance or elevated pre-exercise blood sugars), and the effect of oral hypoglycemic agents or insulin. The medication you use to manage your diabetes will have an effect on the blood glucose response you see with exercise. It is not uncommon, however, for people with diabetes to observe an increase in blood sugar immediately post exercise, particularly when the exercise is of higher intensity or anaerobic in nature. Provided you are not experiencing hypoglycemia related to exercise, then the response you are seeing is truly ideal. Regular exercise improves the way your body uses its own insulin.

Keep up the great work and enjoy your exercise routine!

DMW