Diabetes mellitus leads to macrovascular and microvascular complications, resulting in life-threatening conditions. Exercise is considered an important therapeutic regimen for diabetes mellitus. Exercise in diabetic patients promotes cardiovascular benefits by reducing cardiovascular risk and mortality, assists with weight management, and it improves glycemic control. The increased tissue sensitivity to insulin produces a beneficial effect on glycemic control.
Recommendations about exercise regimen come from the American Heart Association, the American Diabetes Association, and the American College of Sports Medicine standards of medical care in diabetes (2013).
Type 1 and type 2 patients with diabetes are encouraged to do 30 to 60 minutes of moderate-intensity aerobic activity. Patients suffering from diabetes should also be encouraged to perform resistance training at least twice per week. Patients with moderate to severe proliferative retinopathy have contraindications for resistance training. Otherwise, for physically fit patients, a shorter duration of more vigorous aerobic exercise is recommended.
Moderate-intensity aerobic activity: Perform 30 to 60 minutes of moderate-intensity aerobic activity on most days of the week. Begin with 10 minutes of stretching and warm-up, follow that with 15 to 20 minutes of aerobic exercise of person’s choice such as walking, running, swimming, dancing, cycling, or rowing to name few. Maintain regularity in exercise regimen at least three to five times per week. Continue to perform exercise at the same time in relation of meals and insulin injections. Gradual increment in duration and intensity as tolerated by the patient should be planned. Goal is to perform 150 minutes of moderate-intensity aerobic exercise per week.
Resistance training: Exercise with free weights or weight machines. In the absence of contraindications listed above, patients should perform resistance training at least twice per week. Patients should involve the larger group of muscles for exercise training, such as core, upper and lower body. Proliferative retinopathy may cause retinal bleeding due to Valsalva maneuvers with a possibility of marked increase in blood pressure precipitating intraocular bleeding in such patients.
Vigorous aerobic exercise: Patients with diabetes who are generally fit, exercising regularly and have higher aerobic capacity may perform 75 minutes per week of more vigorous aerobic exercise. The preferable regimen is jogging 9.6 km per hour. An alternative regimen can be low-volume, high-intensity training, during which patients exercise more vigorously for a shorter amount of time, such as cycling at 85% to 90% percent of individual maximal heart rate for 60 seconds, followed by 60 seconds of rest, with a total of 10 repetitions. The long-term health effects of low-volume, high-intensity training is unknown. Again, as with moderate excise regimen, a gradual increment in duration and intensity as tolerated by the patient should be planned.
Relative contraindications for exercise regimen include proliferative retinopathy that may cause retinal bleeding due to Valsalva maneuvers with a possibility of a marked increase in blood pressure precipitating intraocular bleeding in such patients. Diabetic neuropathy should avoid traumatic weight-bearing, as it leads to pressure ulcers.
Type 2 Diabetes: Exercise leads to an increase in insulin sensitivity. Patients on oral hypoglycemic have decreased blood glucose concentration after exercise. Studies have suggested that patients who were fasting, no change in blood glucose concentrations noted; whereas, blood concentrations decreased in patients who exercised after eating.
Type 1 Diabetes
Patients have impaired exercise capacity due to generally increased body mass index and advanced age. Reduced skeletal muscle oxidative capacity due to mitochondrial dysfunction has been responsible for impaired exercise capacity. Patients are insulin resistant due to many defects in glucose metabolism.
An exercise program leads to increased activity of mitochondrial enzymes, increased insulin sensitivity, and muscle capillary recruitment. Adding resistance training to aerobic exercise provides an additional benefit of increased insulin sensitivity.
General principles for diabetic patients for exercise regimens:
Long-Term Compliance and an Interprofessional Approach
Maintenance of the exercise program in patients with type 2 diabetes is an important goal because it is associated with long-term cardiovascular benefits and reduced mortality. Primary care physicians and nursing professional diabetes educators caring for patients play an important role in educating these patients of the importance of exercise regimen as a therapeutic option for the disease management. There have been studies which suggested simple behavioral counseling by clinicians and nurse educators during routine clinic visits gave encouraging results for increasing compliance, although long-term follow-up is needed.
Exercise regimens are difficult to maintain for more than 3 months due to intense nature of the programs requiring extra visits for special classes. In a 10-year study of 255 patients with diabetes enrolled in a diabetes education program emphasizing exercise, the rate of compliance fell from 80% for 6 weeks to less than 50% for 3 months. The compliance rate further dropped to less than 20% at 1 year. A coordinated interprofessional approach with educators working with clinicians will help to maximize compliance. (Level V)