I am 16 years old, have had type 1 diabetes for five years, my blood sugars range from 100 to 220 mg/dl [5.6-12.2 mmol/L] daily, and I am very active in sports. Sometimes, even when I’m high (250-500 mg/dl [13.9-27.8 mmol/L]), I continue to run and play the sport, and it sometimes drags me down. Is it unhealthy to do this if I have no ketones? What happens to my body when the blood glucose is so high? Am I doing damage to my brain? What if I’m low? Will I get complications?

Excellent questions about sports and diabetes control. When you exercise your muscles need energy. This is provided by glucose either floating in your blood or stored in the muscle or liver, but you need insulin to use this energy. So, by definition, when your sugars are too high, you don’t have enough insulin at that moment and your muscles continue to “starve” themselves. Therefore, they don’t perform very well. It isn’t clear exactly at what blood glucose level this occurs. Some research suggests this happens when the blood glucose is over 300 mg/dl [16.7 mmol/L], some when it is over 200-250 mg/dl [11.1-13.9 mmol/L]. That’s the reason for suggestions that you do not exercise vigorously when glucose levels are out of control.

Long term complications are a reflections of how long the high blood glucose levels persist and do damage to the blood vessels of the eyes, kidneys, heart and to the nervous system as well. A hemoglobin A1c represents this overall average.

You should ask these same questions to your diabetes team since they can give you specific advice related to your exact situation.

SB