July 9, 2002
Exercise and Sports
Question from Spruce Grove, Alberta, Canada:
My three year old son has type 1 diabetes, and his diabetes team thinks he may be experiencing “delayed” lows after exercise. How long after an activity can a delayed low occur? For example, if he was active in the evening and had a blood glucose reading of 10-15 mmol/L [180-270 mg/dl] at bedtime with no extra snack for activity, could a low reading in the morning be attributed to a delayed low?
It is quite possible that exercise/activity from the evening prior can have a lasting effect blood sugar levels, resulting in episodes of low blood sugar during the night or early morning hours. Significant activity can both raise metabolism and increase insulin sensitivity for hours after.
The normal working pancreas would function to decrease the amount of circulating insulin in response, and the liver might balance blood sugar by releasing glycogen stores. In the adult or child with diabetes, we must try to mimic this in an effort to avoid hypoglycemia. This might be accomplished with a reduction in overnight insulin levels and/or giving a bedtime snack consisting of long-acting carbohydrate and protein sources. Discuss these options with your son’s diabetes team.