ADA Recommendations Regarding Exercise and Type 2 Diabetes Issued

At least 150 minutes per week of moderate to vigorous physical activity and will vary according to goals. That is 30 minutes a day for 6 days a week.

"For decades, exercise has been considered a cornerstone of diabetes management, along with diet and medication," write Ronald J. Sigal, MD, MPH, from the University of Ottawa in Ontario, Canada, and colleagues. "However, high-quality evidence on the importance of exercise and fitness in diabetes was lacking until recent years. The present document summarizes the most clinically relevant recent advances related to people with type 2 diabetes and the recommendations that follow from these."
Recommended lifestyle measures for prevention of type 2 diabetes are as follows:

· People with impaired glucose tolerance should begin and continue a program of weight control, including at least 150 minutes per week of moderate to vigorous physical activity and a healthful diet with modest energy restriction (Level of evidence: A).

· The amount and intensity of recommended aerobic exercise vary according to goals. To improve glycemic control, assist with weight maintenance, and reduce risk for cardiovascular disease (CVD), the panel recommends 150 minutes per week or more of moderate-intensity aerobic physical activity (40% - 60% of oxygen consumption per unit time [VO2max] or 50% - 70% of maximum heart rate), and/or 90 minutes per week or more of vigorous aerobic exercise (> 60% of VO2max or > 70% of maximum heart rate). The physical activity should be distributed over at least 3 days per week, with no more than 2 consecutive days without physical activity (Level of evidence: A).

· Compared with lower volumes of activity, performing at least 4 hours per week of moderate to vigorous aerobic and/or resistance exercise physical activity is associated with greater CVD risk reduction (Level of evidence: B).

· For long-term maintenance of major weight loss (= 13.6 kg or 30 lb), larger volumes of exercise (7 hours per week of moderate or vigorous aerobic physical activity) may be helpful (Level of evidence: B).

· Unless contraindicated, people with type 2 diabetes should be encouraged to perform resistance exercise 3 times per week, targeting all major muscle groups. This should progress to 3 sets of 8 to 10 repetitions at a weight that cannot be lifted more than 8 to 10 times (level of evidence: A). Initial supervision and periodic reassessments by a qualified exercise specialist are recommended to ensure that resistance exercises are performed correctly, to maximize health benefits, and to minimize the risk of injury.

"Because of the increased evidence for health benefits from resistance training during the past 10 - 15 years, the American College of Sports Medicine (ACSM) now recommends that resistance training be included in fitness programs for healthy young and middle-aged adults, older adults, and adults with type 2 diabetes," the authors write. "With increased age, there is a tendency for progressive declines in muscle mass, leading to 'sarcopenia,' decreased functional capacity, decreased resting metabolic rate, increased adiposity, and increased insulin resistance, and resistance training can have a major positive impact on each of these. Resistance exercise improves insulin sensitivity to about the same extent as aerobic exercise."

The authors caution that before beginning a program of physical activity more vigorous than brisk walking, people with diabetes should be evaluated for conditions that might be associated with increased likelihood of CVD or that might contraindicate certain types of exercise or predispose to injury. Examples of such conditions could include severe autonomic neuropathy, severe peripheral neuropathy, and preproliferative or proliferative retinopathy. The patient's age and previous physical activity level should also be considered.

"The role of stress testing before beginning an exercise program is controversial," the authors write. "There is no evidence that such testing is routinely necessary for those planning moderate-intensity activity such as walking, but it should be considered for previously sedentary individuals at moderate to high risk of CVD who want to undertake vigorous aerobic exercise exceeding the demands of everyday living."

To prevent hypoglycemia, patients who take insulin or secretagogues should check capillary blood glucose before, after, and several hours after completing a session of physical activity, at least until their usual glycemic responses to such activity can be predicted. For those prone to hypoglycemia during or after exercise, useful strategies may include reducing doses of insulin or secretagogues before sessions of physical activity, consuming extra carbohydrate before or during physical activity, or both (Level of evidence: E; consensus, clinical experience).

"The most successful programs for long-term weight control have involved combinations of diet, exercise, and behavior modification," the authors conclude. "Exercise alone, without concomitant dietary caloric restriction and behavior modification, tends to produce only modest weight loss of [approximately] 2 kg. Weight loss is typically this small primarily because obese people often have difficulty performing sufficient exercise to create a large energy deficit, and it is relatively easy to counterbalance increased energy expenditure through exercise by eating more or becoming less active outside of exercise sessions."

Practice Pearls:

· Exercise in patients with diabetes has a protective effect on cardiovascular disease and improves glycemic control.
· The benefits of exercise in glycemic control are independent of weight loss. Mechanisms of cardiovascular protection include decreased inflammation, improved early diastolic filling, improved endothelial function, and reduced abdominal fat.
Diabetes Care. 2006;29:1433-1438