I have type 1 diabetes and have very good glucose control, but when I run for exercise in the mornings my blood sugar will go up instead of down. For example, I will test before run and I will be between 180-200 mg/dl [10-11.1 mmol/L], when I get back I will test and it will be around 120 mg/dl [6.7 mmol/L], but about an hour later it will shoot up again to around 180 mg/dl [10 mmol/L] without my eating anything.

You don’t mention how old you are, your insulin regimen, or the dietary program you do to prepare for your run. I’m not sure I can give you a most correct opinion without those, but in general, people do react to exercise a bit differently. Mostly, exercise causes glucose values to decrease as you have noticed, but sometimes not for hours afterwards. The “insulin sensitizing” effects of exercise often last for hours. Perhaps your baseline insulin dose is a bit on the light side?

DS
Additional comments from Delaine M. Wright, Clinical Exercise Physiologist:

It is not entirely uncommon to see a rise in blood sugar related to exercise, particularly when basal insulin levels are low. This rise post exercise can be related to the hormones produced and resulting liver glycogen release during higher intensity exercise. Do your blood sugars at that time of the day stay consistently at 180-200 mg/dl [10-11.1 mmol/L] on the days that you do not run? What is your insulin and dietary regimen like prior to your run? If you desire tighter control around your exercise regimen, your diabetes team should be able to help you make adjustments to your insulin and dietary intake. Your blood sugar monitoring around exercise indicates that you decrease 60-80 mg/dl [3.3-4.4 mmol/L] as a direct result of your run. You’ll have to keep this in mind as you make changes, as you’ll want to prevent exercise-induced hypoglycemia.

Keep up the great work with your exercise regimen and diabetes care!

DMW