A study published in October 2009 in Diabetic Medicine investigated differences in the rates of exercise-induced low blood sugars. A total of 50 people with type 1 diabetes (average age around 39 years and two-thirds men) who already were on a mealtime rapid-acting plus basal insulin regimen exercised for 30 minutes for five hours after their last insulin dose and were followed for another 2.5 hours after finishing. As a basal insulin, they were using either Levemir (generic name: detemir), Lantus (glargine) or NPH (neutral protamine Hagedorn), the dose of which was not altered for the study, and they weren’t allowed to take in any supplemental carbs during the exercise or afterwards unless their sugars got too low. In total only around a quarter of the people on Levemir or NPH had problems with minor hypoglycemia either during or after the exercise, while over half of those (57%) of Lantus users did. The authors’ conclusions were that Levemir and NPH result in fewer hypos than Lantus in well-controlled people with type 1 diabetes during and after exercise. So, what does this mean for you? Use an insulin pump and simply decrease your basal rate for exercise? That’s certainly one option. If you stick with a basal-bolus injection regimen, though, you probably don’t need to change which basal insulin you use based on the results of this one study. Just be sure to monitor your blood sugars frequently to figure out how many carbs you need to supplement with to prevent lows related to exercise.