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From Ontario, Canada:

My nine year old daughter was diagnosed with type 1 seven weeks ago. She is a member of her school cross country team, plays other sports, and runs competitively. We are having difficulty with the early morning training runs she is required to do. She wakes up with pretty good blood sugars, almost always within her target, and then receives a very small amount of fast-acting insulin (one or two units) and about nine units of slower acting. Is there a way that she can do the training run when she gets up, before eating breakfast? Her training run is usually only one-half hour. She could come home, have her insulin injection and eat her breakfast before going to school. What would this do to her blood sugars? What do you advise for young, type 1 athletes who are supposed to participate in these early-morning workouts and practices? It's just difficult to eat a proper breakfast then do hill training immediately afterwards. Do you have any suggestions?


Typically, in the morning, insulin levels are low due to not eating since the night before. Since there is no fast-acting insulin (Humalog or NovoLog) on board, the main concern would be the slower acting insulin. Depending on what type of slower acting insulin (Lantus, NPH, or Lente) being used, it can be cut back either the night before or even the morning before working out. Having type 1 diabetes only seven weeks indicates insulin is still be produced (Honeymooning). Depending on the prescribing doctor's recommendation, maybe the morning (slower acting) insulin can be delayed until after the run.

It is important to have food prior to the run to fuel the activity. Cutting back on the fast acting insulin by 50%, for the food eaten prior to the activity is a technique used by athletes which may cut down on the low blood sugars. Since the fast acting insulin peaks about 60 to 90 minutes after taking it athletes need to watch for low blood sugars during this time.

Having a target blood sugar prior to exercise is a good practice. This target is usually higher than what most athletes are comfortable with when not exercising. Aerobic exercise (running) can cause blood sugars to go low during and, more likely, afterwards, but anaerobic exercise (higher intensity - maybe hills) can cause blood sugars to go up. Much of this is dependent on how much insulin is on board. A good target pre-exercise blood sugar may be 150 mg/dl [8.3 mmol/L], but if low blood sugars are a problem 200 mg/dl [11.1 mmol/L] is not unusual to try.

It is recommended to at least have a blood sugar of 100 mg/dl [5.6 mmol/L] prior to activity or exercise should be delayed. The guidelines for delaying exercise for high blood sugars are 240 mg/dl to 300 mg/dl [13.3 to 16.7 mmol/L] with ketones or 300 mg/dl [16.7 mmol/L] and above with or without ketones.


Original posting 18 Oct 2005
Posted to Exercise and Sports


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