Exercise and Diabetes. Sheri R. Colberg

out her more vigorous training days and intersperse more moderate ones in between them.

      Duration: MF’s recommended duration is inversely related to her exercise intensity, meaning that working out harder requires a shorter duration. She should aim to do at least 20 min of vigorous physical activity or 30 min/session of moderate training, with a target training goal of 60–75 min of vigorous or 150 min of moderate exercise weekly, or a combination thereof. As a rule of thumb, 1 min of vigorous exercise is equivalent to 2 min of moderate activity.

      Progression: Given her initial fitness status and prior sports history, MF can likely begin in the improvement phase of training. Initially, she may choose to only work out 3 nonconsecutive days/week, working up to 5 days/week, depending on her training intensity. Once she has established her aerobic training routine, she should consider adding in some resistance training at least 2 days/week to enhance her muscular strength as well. As she goes into the maintenance phase, she should continue to vary her activities or add in new ones for variety, additional fitness gains, injury prevention, and motivation to continue her training.

      Daily Movement: Due to MF’s interest in losing weight, she should engage in more daily movement as well, including fidgeting, standing, and taking more steps during the day, to maximize her daily caloric expenditure. Doing so will help keep her blood glucose at a lower level.

      Possible Precautions: Because MF has not had T1D for that long and has minimal risk factors for cardiovascular disease, she should not be required to have any testing done before starting an exercise program. MF should be advised to have her health-care provider prescribe a glucagon pen that she can keep in her dorm room as a treatment for severe hypoglycemia. She should instruct both her roommate and her dorm’s resident assistant how to give her a glucagon injection, should the need arise.

      Regimen Changes: Because weight loss is a stated goal, MF will need to be especially vigilant about preventing hypoglycemia since the extra calories taken in during treatment of lows may sabotage her attempts to lose weight. Her insulin use does require planning ahead with appropriate insulin dosing and food intake changes to prevent hypoglycemia both during and following any physical activity. She will need to use SMBG frequently as she begins her training program—before, possibly during, and several times after exercising—to establish her usual responses to exercise and blood glucose trends. During exercise sessions, she should always have a rapid-acting carbohydrate like glucose tablets or gels readily available to treat low blood glucose with a minimal amount of calories. Once she starts exercising regularly, her basal insulin needs will likely decrease, and she may need to lower her bedtime dose of insulin glargine or eat a bedtime snack (but for weight-loss reasons, it would be better to minimize the need for additional snacking). Furthermore, for exercise sessions done within 1–2 h of a meal, she should consider decreasing her meal insulin (lispro) dose by up to 75% to prevent hypoglycemia during the activity, and she may need less insulin later in the day at subsequent meals.

      Individuals of all ages with T1D can and should participate in regular physical activity for better health, although appropriate diabetes regimen changes must be made if improved blood glucose management is an expected outcome. Cardiorespiratory fitness levels may be lower in some individuals with T1D, and their metabolic responses to exercise can be altered by hyperglycemia. Prevention of hypoglycemia related to physical activity will likely require greater carbohydrate intake, reductions in insulin doses (or changes in timing), or both. Fear of hypoglycemia is the biggest barrier to exercise participation, but when diabetes is managed properly, youth and adults with T1D can participate in recommended amounts of physical activity following the same guidelines as their counterparts who do not have diabetes.

      Professional Practice Pearls

      • Regular exercise lowers blood pressure, lipid levels, body weight, mortality risk, and risk of complications while raising cardiorespiratory fitness levels, muscular strength, quality of life, and sense of well-being in individuals with T1D.

      • Appropriate diabetes regimen changes must be made if improved blood glucose management is an expected outcome of regular physical activity.

      • Some, but not all, individuals with T1D have the same aerobic capacity as similar-age people without diabetes.

      • Moderate exercise usually causes a decline in blood glucose levels; conversely, high-intensity training can maintain more stable levels or possibly result in hyperglycemia.

      • When engaging in regular physical activity, individuals with T1D will need to self-monitor their blood glucose levels to establish responses and make regimen changes.

      • Regimen changes to manage glycemic balance with physical activity will likely involve greater food intake, changes in insulin doses and timing, or both.

      • A novel approach to hypoglycemia prevention involves engaging in a 10-s maximal sprint immediately before or at the end of a bout of moderate activity.

      • Adults with T1D should engage in at least 150 min a week of moderate exercise, 60–75 min of vigorous aerobic exercise, or a combination thereof on 3–5 days/week (depending on intensity).

      • Deconditioned adults can start out with lower-intensity activities and progress slowly over weeks to months, or start with the improvement phase if fitness adequate.

      • Youth with T1D should engage in at least 60 min or more of physical activity daily, 7 days/week, including aerobic, muscle-strengthening, and bone-strengthening activities.

      • Children and adolescents should start out slowly if deconditioned, but all should progress to engaging in vigorous activity at least three times weekly.

      • Youth should vary activities, but it is possible for them to meet the recommended levels of physical activity by doing free play, structured programs, or both.

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