Get Your Doctor's okay Before You Start Exercising This is especially important if you are older than age 35, have had diabetes for more than ten years, have any complications of diabetes, have not exercised in a long time, or have heart disease. Exercise has the same effect on blood L glucose as insulin. It lowers blood glucose, making you more sensitive to insulin. This is a benefit of exercise that can also pose a problem if it lowers your blood glucose too much