Diabetes Mellitus and Exercise

Bernard Zinman, MD; Neil Ruderman, MD, Phil; Barbara N. Campaigne, PhD; John T. Devlin, MD; Stephen H. Schneider, MD.


March 01, 2010

In This Article

Exercise and Type 1 Diabetes

All levels of exercise, including leisure activities, recreational sports and competitive professional performance, can be performed by people with type 1 diabetes who do not have complications and are in good blood glucose control(note previous section). The ability to adjust the therapeutic regimen(insulin and diet) to allow safe participation and high performance has recently been recognized as an important management strategy in these individuals. In particular, the important role played by the patient in collecting self-monitored blood glucose data of the response to exercise and then using this information to improve performance and enhance safety is now fully accepted.

Hypoglycemia which can occur during, immediately after, or many hours after exercise can be avoided. This requires that the patient have both an adequate knowledge of the metabolic and hormonal responses to exercise and well-tuned self-management skills. The increasing use of intensive insulin therapy has provided patients with the flexibility to make appropriate insulin dose adjustments for various activities. The rigid recommendation to use carbohydrate supplementation, calculated from the planned intensity and duration of exercise, without regard to glycemic level at the start of exercise, the previously measured metabolic response to exercise, and the patient's insulin therapy, is no longer appropriate. Such an approach not infrequently neutralizes the beneficial glycemic lowering effects of exercise in patients with type 1 diabetes.

General guidelines that may prove helpful in regulating the glycemic response to exercise can be summarized as follows:

  1. Metabolic control before exercise

    • Avoid exercise if fasting glucose levels are > 250 mg/dl and ketosis is present of if glucose levels are > 300 mg/dl, irrespective of whether ketosis is present

    • Ingest added carbohydrate if glucose levels are < 100 mg/dl.

  2. Blood glucose monitoring before and after exercise

    • Identify when changes in insulin or food intake are necessary

    • Learn the glycemic response to different exercise conditions.

  3. Food intake

    • Consume added carbohydrate as needed to avoid hypoglycemia

    • Carbohydrate-based foods should be readily available during and after exercise.

Since diabetes is associated with an increased risk of macrovascular disease, the benefit of exercise in improving known risk factors for atherosclerosis is to be highly valued. This is particularly true in that exercise can improve the lipoprotein profile, reduce blood pressure and improve cardiovascular fitness. However, it must also be appreciated that several studies have failed to show an independent effect of exercise training on improving glycemic control as measured by HbA1c in patients with type 1 diabetes. Indeed, these studies have been valuable in changing the focus for exercise in diabetes from glucose control to that of an important life behavior with multiple benefits. The challenge is to develop strategies which allow individuals with type 1 diabetes to participate in activities that are consistent with their lifestyle and culture in a safe and enjoyable manner.

In general, the principles recommended for dealing with exercise in adults with type 1 diabetes, free of complications, apply to children, with the caveat that children may be prone to greater variability in blood glucose levels. In children, particular attention needs to be paid to balancing glycemic control with the normalcy of play, and for this the assistance of parents, teachers, and athletic coaches may be necessary. In the case of adolescents, hormonal changes can contribute to the difficulty in controlling blood glucose levels. Despite these added problems, it is clear that with careful instructions in self management and the treatment of hypoglycemia, exercise can be a safe and rewarding experience for the great majority of children and adolescents with insulin dependent diabetes mellitus.