Exercise

Introduction

Many adults with diabetes are sedentary and obese, which can contribute to the development of glucose intolerance. Therefore, physical activity should be included as an essential treatment component in the diabetes management plan unless contraindicated in a given individual. Current research suggests that even low-level regular exercise can prevent or delay the onset of type 2 diabetes (T2D) in susceptible, high-risk individuals.

Benefits

The potential benefits of regular exercise include:

• Improved blood glucose control because of enhanced insulin sensitivity
• Weight loss or maintenance of a desirable body weight because of increased energy expenditure
• Improved cardiovascular (CV) risk factors (lipids, blood pressure, etc.)
• The potential to reduce the dosage of or the need for insulin or oral antidiabetic drug (OADs)
• A slowing of the decline in mobility of patients
• Improved energy level, CV fitness, muscular strength, flexibility, quality of life and sense of well-being.

Precautions and Considerations

Because many people with diabetes have not been active and are deconditioned, exercise should be started cautiously at a low level and gradually increased to avoid adverse effects such as injury, hypoglycemia, or cardiac problems. Most adults with diabetes should have a physical examination, including a stress test, before beginning to exercise to rule out significant CV disease or silent ischemia and to determine the presence of any diabetic complications. Strenuous activity is not recommended for patients with poor metabolic control or for those with significant complications. Mild to moderate exercise is important with the guidance of the physician.

Patients being treated with insulin secretagogues or insulin alone or in combination are susceptible to hypoglycemia during exercise or for as much as 12 hours after. To prevent hypoglycemia, such patients should use self-monitoring of blood glucose (SMBG) both before and after exercising to determine their response to varying degrees of physical activity. Appropriate consumption of snacks and modification of pharmacotherapy, as needed, can help avoid most problems. More important, establishing and following a regular exercise program can reduce the likelihood of exercise-induced episodes of hypoglycemia.

Long-term complications of diabetes can complicate the exercise regimens of patients with diabetes. Vigorous aerobic or resistance exercises post a risk of inducing vitreous retinal detachment or hemorrhage in patients with diabetic retinopathy, so these types of exercises may be contraindicated. Although studies have shown that moderate-intensity walking may not increase the risk of foot ulcers in patients with peripheral neuropathy, individuals should examine their feet daily for lesions after exercising. Individuals with foot injuries or sores should not perform weight-bearing activities. Autonomic neuropathy can increase the risk of exercise-associated injury, so patients with diabetic autonomic neuropathy should undergo cardiac investigation before beginning an exercise regimen.

Exercise Prescription

Any exercise prescription should be individualized to account for patient interests, physical status and capacity and motivation. Although having a planned program of physical activity is ideal, exercise is so important and beneficial that just getting patients moving is a worthwhile initial goal. Patients should choose activities that are appropriate for their general physical condition and lifestyle, start slowly and work up to their target goal. The American Diabetes Association (ADA) recommends that adults over the age of 18 perform 150 minutes of moderate-intensity exercise or 75 minutes of vigorous-intensity exercise per week (or a combination of the two). In addition, it is recommended that adults perform two to three sessions of resistance exercise on non-consecutive days. Children with diabetes or prediabetes are encouraged to exercise for at least 60 minutes each day, including vigorous aerobic, muscle-strengthening and bone-strengthening activities during at least three of these days. Adults over the age of 65, or patients with disabilities, should try to follow the adult guidelines, or be as physically active as they can be. In particular, flexibility training and balance training are recommended 2–3 times/week for older adults. Subject to individual preference, yoga or tai chi are recommended to increase flexibility, muscular strength and balance. Guidelines from the American College of Sports Medicine on exercise and physical activity in patients with T2D are in broad agreement with the ADA guidelines.

In all individuals, sedentary behavior (e.g., working at a computer, watching television) should be reduced and bouts of >30 minutes should be broken up by intermittently standing, walking, or performing other light physical activities. Example aerobic activities include:

• Walking at a moderate pace (3 to 5 mph)
• Housework
• Gardening
• Dancing
• Biking and stationary cycling
• Lap swimming and aerobic water exercises.

Guidelines for safe exercise should be reviewed with patients (Table 6-1). Recommendations for a practical exercise prescription are outlined in Table 6-2.

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