My 14-year-old son recently started biking to school (probably a 4 kilometer/approximately 2.5 mile journey). He tests his blood sugar level before leaving and again when he gets to school. For some reason, we are finding that often his blood sugar level will have shot up on the way. He can be 9 or 10 mmol/L (162 or 180 mg/dl) at home, but by the time he gets to school, he might be 20 mmol/L (360 mg/dl). This does not happen every time and we are unable to predict when it will so we cannot safely preempt anything. He was diagnosed 10 years ago and is on an insulin pump. He also has coeliac disease. Are you able to shed any light on this? Any input would be appreciated.

A few things to think about…

Does your son vary the intensity of his bicycling? (i.e., does he ride faster on some days than others?) This could have an impact. We know that if the activity is anaerobic (without oxygen) as opposed to aerobic (with oxygen) that there could be a rise in the blood sugar, so, if there are some days when he rides at full steam (because he’s late for the start of school perhaps?) this could be the reason.

How soon is he riding after his morning meal and what is the blood sugar several hours later? The spike could be the result not of the bike ride, but of the morning meal.

And, lastly, (and this is one I was guilty of at his age) does he snack at all on the way to school? This isn’t a bad thing, as long as he is honest about it.

BF