Your patient is a middle-aged man with type 2 diabetes who wants to start a weight-training program. What recommendations would you offer him? Another patient with diabetes has peripheral neuropathy; which types of exercise are safest for her? Answers to these and other questions about physical activity by patients who have diabetes mellitus can be found in guidelines from the American Diabetes Association (ADA).1 Highlights of those recommendations are presented here.
Encourage your patients with diabetes to be as physically active as they are able. The goal is to follow the US Department of Health and Human Services’ Physical Activity Guidelines for Americans, which recommend that adults over age 18 years perform at least 150 minutes per week of moderate-intensity aerobic physical activity.2 In addition, encourage patients with type 2 diabetes to perform resistance training 3 times per week, unless they have diabetic complications that prohibit such exercise.
TYPE 2 DIABETES AND EXERCISE
Strongly encourage patients with type 2 diabetes to exercise regularly. Among the specific benefits of a long-term exercise program for these patients are:
•Improved glycemic control.
•Reduced risk of cardiovascular disease.
•Improved lipid levels.
•Reduced blood pressure.
A meta-analysis found that structured exercise interventions of at least 8 weeks’ duration lowered hemoglobin A1c levels by an average of 0.66% in persons with type 2 diabetes, even when there was no significant change in body mass index.3 In addition, regular exercise may help forestall the development of diabetes in persons who are at high risk for the disease.4
TYPE 1 DIABETES AND EXERCISE
Exercise can worsen hyperglycemia and ketosis in persons with type 1 diabetes who have been deprived of insulin for 12 to 48 hours.1 Thus, caution patients to avoid vigorous activity if ketosis is present. However, it is not necessary to postpone exercise on the sole basis of hyperglycemia, provided the patient feels well and urine and blood tests are negative for ketones.
EVALUATION BEFORE EXERCISE
Previous guidelines had recommended assessment of patients with diabetes who have multiple cardiovascular risk factors for coronary artery disease (CAD). More recent guidelines, however, advise against routine screening of patients with diabetes who have no symptoms of CAD.5 Use your clinical judgment, and take into consideration the patient’s age and previous activity level. For example, it would be prudent to recommend that high-risk patients start with short periods of low-intensity exercise and then increase the duration and intensity slowly.
Focus the evaluation on identifying complications that might preclude certain activities or predispose the patient to injury, such as uncontrolled hypertension, severe autonomic neuropathy, severe peripheral neuropathy, a history of diabetic foot or leg ulcers, and unstable proliferative retinopathy.
Hypoglycemia. Physical activity can cause hypoglycemia in patients with diabetes who take insulin and/or insulin secretagogues if the medication dose or carbohydrate consumption is not adjusted to compensate. Advise patients who are receiving these therapies to consume additional carbohydrate if pre-exercise glucose levels are lower than 100 mg/dL.1 Hypoglycemia is rare in persons with diabetes who are not treated with insulin or insulin secretagogues.
Retinopathy. If the eye examination reveals proliferative diabetic retinopathy or severe nonproliferative diabetic retinopathy, vigorous aerobic or resistance exercise is contraindicated because it may cause vitreous hemorrhage or retinal detachment.1 Low-impact activities, such as swimming or stationary cycling, are acceptable, but running and weight lifting should be discouraged.
Peripheral neuropathy. Previous guidelines advised against weight-bearing exercise for patients with severe peripheral neuropathy; however, more recent studies have shown that moderate-intensity walking does not increase the risk of foot ulcers.6 Tell patients to wear proper footwear and to examine their feet for blisters and other injuries both before and after each exercise session. Those who have a foot injury or ulcer should avoid weight-bearing physical activity.
Autonomic neuropathy. Cardiac autonomic neuropathy associated with diabetes has been linked to sudden death and silent myocardial ischemia.1 Thus, a cardiac evaluation that includes appropriate noninvasive testing is recommended before patients with autonomic neuropathy increase their level of physical activity. These patients are also more likely to experience hypotension or hypertension at the start of an exercise program or after a vigorous session. Because these patients have difficulty with thermoregulation, they should not exercise in hot or cold environments and should drink plenty of fluids while working out.
Nephropathy. Because vigorous exercise does not increase the rate of progression of diabetic kidney disease, patients do not need to limit their physical activity.1
1. American Diabetes Association. Standards of medical care in diabetes—2010. Diabetes Care. 2010;33(suppl 1):S11-S61.
2. U.S. Department of Health and Human Services. 2008 Physical Activity Guidelines for Americans. Atlanta, Ga: Centers for Disease Control and Prevention.
3. Boulé NG, Haddad E, Kenny GP, et al. Effects of exercise on glycemic control and body mass in type 2 diabetes mellitus: a meta-analysis of controlled clinical trials. JAMA. 2001;286:1218-1227.
4. Knowler WC, Barrett-Connor E, Fowler SE, et al, for the Diabetes Prevention Program Research Group. Reduction in the incidence of type 2 diabetes with lifestyle intervention or metformin. N Engl J Med. 2002;346:393-403.
5. Bax JJ, Young LH, Frye RL, et al. Screening for coronary artery disease in patients with diabetes. Diabetes Care. 2007;30:2729-2736.
6. Lemaster JW, Reiber GE, Smith DG, et al. Daily weight-bearing activity does not increase the risk of diabetic foot ulcers. Med Sci Sports Exerc. 2003;35:1093-1099.