My daughter was diagnosed with type 1 diabetes almost a year ago. She is very active, playing travel soccer, skating, and tennis. At first, exercise used to make her blood glucose go lower but, lately, oftentimes it raises her blood glucose level. This does not seem to make sense since she is active and using lots of energy. What are the factors that help determine if exercise will make a diabetic go higher or lower? We know that she should not exercise if her blood sugar is above 300 mg/dl [16.7 mmol/L].

Typically, exercise that is aerobic (using oxygen) in nature (i.e., running, cycling, and swimming) and is done over a period of time will tend to lower one’s blood sugar. Athletes who exercise longer than they are used to may experience low blood sugar, especially in the 24 hours following exercise.

Exercise can cause blood sugars to rise, too. Anaerobic exercise (without oxygen), such as sprinting or resistance training, can cause blood sugars to rise. Anything recognized as a stress to the body will cause hormonal activity releasing stress hormones (i.e., cortisol, adrenaline, growth hormone) signaling the liver to release glycogen. This glycogen, that is the stored form of glucose, circulates into the blood stream, increasing blood sugar.

RP