INTRODUCTION — Exercise is being increasingly promoted as part of the therapeutic regimen for diabetes mellitus. In addition to its cardiovascular benefits, exercise can also improve glycemic control. The beneficial effect on glycemic control largely results from increased tissue sensitivity to insulin.

To understand how these changes occur, it is helpful to begin by briefly reviewing the short- and long-term effects of exercise in normal individuals. Subsequently, the benefits of exercise in patients with type 1 and 2 diabetes and a program for physical activity are reviewed here.

The glycemic benefits of combined diet and exercise interventions in patients with diabetes, exercise for the prevention of type 2 diabetes, and sample cases illustrating problems that can occur when exercise is performed in patients treated with an intensive insulin regimen are discussed separately. (See "Cases illustrating the effects of exercise in intensive insulin therapy for type 1 diabetes mellitus" and "Initial management of hyperglycemia in adults with type 2 diabetes mellitus", section on 'Intensive lifestyle modification' and "Prevention of type 2 diabetes mellitus", section on 'Exercise'.)

EXERCISE AND MUSCLE METABOLISM — Exercise has both short- and long-term effects on metabolism in nondiabetic subjects [1].

Short-term effects — As a person exercises, the muscles initially use glucose in the muscle and later convert muscle glycogen to glucose to provide energy. An average, 70-kg adult man has approximately 1100 kcal stored as muscle glycogen and another 400 to 500 kcal stored as liver glycogen. Skeletal muscle differs from liver in that it lacks the enzyme glucose-6-phosphatase, which converts glucose-6-phosphate (derived from glycogen) to glucose; as a result, muscle glycogen can only be used as an energy source for muscle via the metabolism of glucose-6-phosphate to pyruvate. Glucose cannot be transferred out of muscle to prevent hypoglycemia (figure 1).

In addition to utilizing muscle glycogen, exercising muscle also takes up glucose from the circulation, a process that largely requires the availability of insulin. As the blood glucose concentration begins to fall, the secretion of insulin decreases while that of glucagon rises. The net effect is increased hepatic glucose production due both to glycogenolysis and to gluconeogenesis, in which glucose is formed from lactate, pyruvate, alanine and other amino acids, and glycerol (figure 1).

If the exercise continues, counterregulatory hormones other than glucagon (epinephrine, norepinephrine, growth hormone, and cortisol) play an increasing role. Epinephrine and norepinephrine stimulate hepatic glucose production to some extent, but their major effect is to stimulate lipolysis. Triglycerides are broken down into both free fatty acids, which are utilized as fuel by exercising muscles, and glycerol, which can be converted to glucose in the liver. These changes in hormone release and muscle metabolism become more pronounced with prolonged exercise; insulin secretion continues to fall, while there is a further increase in the release of the counterregulatory hormones. The net effect is a gradual reduction in muscle glucose uptake combined with stimulation of lipolysis and increased free fatty acid uptake by muscle (figure 2) [2,3].

Long-term training effects — Moderate, aerobic exercise on a regular, long-term basis has several effects on muscle function that lead to more efficient use of energy. These changes include increases in the quantity of mitochondrial enzymes and the number of "slow-twitch" muscle fibers and the development of new muscle capillaries [3]. There is also increased translocation of insulin-responsive glucose transporters (GLUT4) from intracellular stores to the cell surface. GLUT4 promotes glucose uptake, which probably explains the overall increase in insulin sensitivity [4].

Several types of exercise, including traditional aerobic, resistance, and high-intensity, low-volume training, have been shown to improve skeletal muscle adaptation [3,5-8]. Exercise, without weight loss, also appears to increase lipid metabolism. In a study of 18 sedentary, nondiabetic adults doing moderate-intensity exercise for six months, the increase in insulin sensitivity was associated with a significant increase in post-heparin plasma lipase and hepatic lipase activity [9]. The increase in the former correlated with a decrease in waist circumference and in body mass index. There is a graded relationship between exercise and improvements in serum lipid profiles. In a study of 111 sedentary, overweight men and women with mild to moderate dyslipidemia, those who exercised the most had the greatest improvements in serum lipid concentrations [10]. This effect was independent of change in body weight. (See "Effects of exercise on lipoproteins and hemostatic factors".)

EXERCISE IN DIABETIC ADULTS — As in normal individuals, exercise has both short- and long-term effects on carbohydrate metabolism in diabetic patients.

Short-term effects in type 1 and 2 diabetes — In patients with type 2 diabetes, short-term exercise training improves insulin sensitivity as it does in nondiabetics [11-13]. In patients with type 2 diabetes treated with an oral hypoglycemic drug, exercise tends to lower blood glucose concentrations. However, this effect may depend upon the timing of the patients' last meal. In one study, there was no change in blood glucose concentrations in patients who were fasting before exercise, but the concentrations decreased in patients who exercised after eating [14].

The physiologic responses to exercise are modified in patients with type 1 diabetes, depending upon the serum insulin concentration at the time of exercise and upon the site and timing of recent insulin injections. Well-controlled type 1 diabetic patients with adequate serum insulin concentrations will usually have a fall in blood glucose concentrations that is much larger than that in normal individuals (figure 3) [15]. Several factors contribute to this response:

●Exogenous insulin cannot be shut off, thereby maintaining muscle glucose uptake and inhibiting hepatic glucose output.

●The increased temperature and blood flow associated with exercise may speed insulin absorption from subcutaneous depots, resulting in higher serum insulin concentrations. This effect is most prominent if the injection was recent, was given into an arm or leg that is being exercised [16], or was inadvertently given intramuscularly [17].

In contrast, exercise can cause a paradoxical elevation in blood glucose concentrations in diabetic patients with poor metabolic control (blood glucose concentration above 250 mg/dL [13.9 mmol/L]), hypoinsulinemia, and some ketonuria. In these patients, the following factors come into play:

●The lack of insulin impairs glucose uptake by muscles and cannot prevent an increase in hepatic glucose output that is mediated by counterregulatory hormones, particularly epinephrine, cortisol, and growth hormone. These hormonal changes also lead sequentially to increased lipolysis and enhanced conversion of the free fatty acids to ketones (figure 3) [15].

Long-term effects in type 2 diabetes — The long-term effects of exercise are somewhat different in patients with type 1 and type 2 diabetes. At baseline, patients with type 2 diabetes have impaired exercise capacity, due primarily to age and increased body mass index. In addition, exercise capacity in type 2 diabetes is affected by subclinical left ventricular dysfunction and cardiac autonomic dysfunction [18]. Other factors that may contribute to impaired exercise capacity have been proposed, including reduced skeletal muscle oxidative capacity due to mitochondrial dysfunction [19,20].

Patients with type 2 diabetes are insulin resistant, an effect that can be mediated by several different defects in glucose metabolism (see "Pathogenesis of type 2 diabetes mellitus"). The defects include [21,22]:

●Decreased number and function of both insulin receptors and glucose transporters

●Decreased activity of some intracellular enzymes (including pyruvate dehydrogenase and glycogen synthase)

●A low maximal oxygen uptake (VO₂max) during exercise

Some of these defects improve during exercise training programs lasting 2 to 24 weeks. The favorable changes include increased activity of mitochondrial enzymes (thereby improving muscle energetics), increased insulin sensitivity, and muscle capillary recruitment [8,11,23-25]. There is, however, little or no increase in the number of muscle capillaries in patients with type 2 diabetes and microvascular complications [25].

The addition of resistance training to aerobic exercise provides additional benefit for glucose disposal. As an example, in a study of 28 obese postmenopausal women with type 2 diabetes randomly assigned to no exercise, aerobic exercise alone, or aerobic exercise plus resistance training, both exercise groups had reductions in abdominal and visceral adipose tissue, an increase in muscle density, and improvements in insulin sensitivity compared with the control group [26]. The greatest improvement in insulin sensitivity was in the combined exercise group.

Glycemic control — Exercise improves glycemic control in patients with type 2 diabetes, as illustrated by the findings of several meta-analyses of trials examining the effect of exercise on glycemic control in patients with type 2 diabetes [27-30]. Exercise training reduces glycated hemoglobin (A1C) values by approximately 0.5 to 0.7 percentage points compared with control participants.

Some trials suggest that combined aerobic and resistance training may be superior to either exercise alone [31,32]. As examples:

●In a trial of 251 adults with type 2 diabetes randomly assigned to resistance, aerobic, combined exercise, or control groups, all three exercise groups were associated with improvements in A1C compared with controls (absolute change in A1C -0.38 to -0.97 percentage points) [31]. The combined exercise program was associated with the greatest reduction in A1C (approximately 1 percentage point compared with controls). However, the combined program was also associated with a longer duration of exercise than the other groups, which may account for the greater improvement in glycemic control.

●In another trial of resistance training, aerobic exercise, combined aerobic and resistance training, or no exercise in 262 sedentary adults with type 2 diabetes, the duration of exercise (140 to 150 minutes/week) was similar in all exercise groups [32]. After nine months, mean A1C decreased modestly in all exercise groups (-0.04 to -0.23 percentage points compared with a 0.11 percentage point increase in the control group). The absolute difference in A1C was significantly improved only in those assigned to the combined program compared with controls (between-group difference 0.34 percent). The combined group also lost significantly more weight than the control and resistance training groups (-1.5, +0.4, and -0.3 kg, respectively), a finding that may account for the greater reduction in A1C.

High-intensity (low-volume) exercise may also improve glycemic control in patients with type 2 diabetes. In one study, seven adults with type 2 diabetes had continuous glucose monitoring for 24 hours on two separate days (an exercise day and a control day) [24,33]. The exercise regimen consisted of cycling at 90 percent of individual maximal heart rate for 60 seconds, followed by 60 seconds of rest, repeated 10 times (total training session 20 minutes with 10 minutes of cycling and 10 minutes resting). The six patients who were taking oral agents continued them during the study. Several measures of glycemic control (three-hour postprandial glucose area under the curve, average post-meal peak glucose concentration, average blood glucose 60 to 120 minutes following meals, proportion of time spent in hyperglycemia) were significantly better on the exercise day. Twenty-four-hour average glucose tended to be lower (130 versus 140 mg/dL on the control day [7.2 versus 7.8 mmol/L]), but the difference was not statistically significant. Additional studies of this type of exercise training are needed in patients with type 2 diabetes, with longer term outcomes and in comparison with traditional forms of exercise.

Thus, traditional aerobic, resistance, and possibly high-intensity, low-volume exercise regimens can improve glycemic control. When the duration of exercise is fixed (ie, 150 minutes/week), a combined program is optimal. Higher levels of exercise intensity are associated with greater improvements in A1C [30]. In addition, long-term compliance is essential to achieve the glycemic benefits of exercise [34] (see 'Long-term compliance' below). Patients with diabetes are encouraged to perform at least 150 minutes of moderate-intensity aerobic exercise per week [35]. In the absence of contraindications (ie, moderate to severe proliferative retinopathy), patients should be encouraged to perform resistance training (exercise with free weights or weight machines) at least twice per week. (See 'A program for physical activity' below.)

Cardiovascular disease and mortality — In several randomized trials, exercise has been shown to improve cardiovascular risk factors (dyslipidemia, blood pressure, and body composition) in patients with type 2 diabetes [29]. However, no clinical trials to date have demonstrated a reduction in major cardiovascular endpoints or mortality. In prospective cohort studies, exercise was associated with improvement in cardiovascular outcomes and a reduction in cardiovascular and overall mortality in patients with type 2 diabetes or with impaired glucose tolerance and cardiovascular disease [36-39]. As examples:

●Among the 5125 women who reported having type 2 diabetes in the Nurses' Health Study, the women who spent at least four hours per week performing moderate (including walking) or vigorous exercise had a 40 percent lower risk of developing cardiovascular disease (including coronary heart disease and stroke) than those who did not [38]. This improvement in risk remained after adjustment for smoking, body mass index, and other cardiovascular risk factors.

●In a prospective cohort study of 2896 diabetic adults, those who walked for at least two hours per week had lower cardiovascular mortality rates when compared with inactive individuals (hazard ratio [HR] 0.66, 95% CI 0.45-0.96; 1.4 versus 2.1 percent per year, respectively) [36]. Rates were even lower for those who walked three to four hours per week (HR 0.47, 95% CI 0.24-0.91). The protective effect was independent of sex, age, race, body mass index, duration of diabetes, comorbid conditions, and physical limitations. The authors calculated that one death per year would be prevented for every 61 adults with diabetes who could be persuaded to walk at least two hours per week. (See "Exercise and fitness in the prevention of atherosclerotic cardiovascular disease".)

●In meta-analyses of prospective cohort studies examining the impact of exercise and cardiorespiratory fitness on all-cause mortality in type 2 diabetes, compared with the lowest level of habitual physical activity, the highest level of physical activity was associated with lower overall mortality risk (relative risk [RR] 0.60, 95% CI 0.52-0.70) [39,40].

●In a prospective cohort study (within a randomized trial that examined the effects of pharmacologic therapy on cardiovascular events), there was a graded inverse association between daily ambulatory activity (as assessed by a pedometer) and a composite endpoint of death from cardiovascular causes, nonfatal myocardial infarction, and nonfatal stroke (HR per 2000 steps 0.90, 95% CI 0.84-0.96) [41]. The primary study compared nateglinide and valsartan with placebo in patients with impaired glucose tolerance and either existing or at least one other risk factor for cardiovascular disease.

Long-term compliance — These beneficial effects have been hard to maintain for more than three months when implemented as fairly intensive programs requiring extra visits for special classes [42,43]. As an example, in a 10-year study of 255 diabetic patients enrolled in a diabetes education program that emphasized exercise, compliance fell from 80 percent at six weeks to less than 50 percent at three months to less than 20 percent at one year [42]. However, studies using simple behavioral counseling by clinicians during routine clinic visits to promote sustained commitment to an exercise program have shown encouraging results [44-47].

Several factors may contribute to the inability to sustain an exercise regimen in patients with type 2 diabetes. Most patients are trying to change a lifetime of sedentary behavior and continued compliance is a major problem [42]. The Third National Health and Nutrition Examination Survey (NHANES III) found that most diabetic patients were physically inactive [48]. Of 1480 diabetic adults, 31 percent reported no physical activity at all, and another 38 percent reported less than the recommended levels of activity.

In addition to decreased exercise capacity, occult coronary or peripheral vascular disease or diabetic neuropathy can limit exercise tolerance.

Despite these difficulties, maintenance of an exercise program in patients with type 2 diabetes remains a worthwhile goal because compliance is associated with long-term cardiovascular benefits and reduced mortality.

Long-term effects in type 1 diabetes — In contrast to the response in type 2 diabetes, there is less evidence that regular exercise is associated with improved glycemic control in patients with type 1 diabetes, presumably due to the lesser importance of insulin resistance in these patients. In a meta-analysis of studies assessing the overall effects of exercise on chronic glycemic control, aerobic exercise (12 studies) was associated with improved glycemic control, whereas resistance training (two studies), combined aerobic and resistance training (four studies), and high-intensity exercise (one study) did not significantly improve chronic glycemic control [49].

There may be substantial beneficial effects of exercise on general well-being, hypertension, and other cardiovascular risk factors, independent of glycemic control.

Patients with type 1 diabetes can tolerate even vigorous exercise, including participation in competitive triathlons and marathons [50,51]. The exercise should optimally be performed at the same time of day in relation to meals and insulin injections. When that is done, the change in blood glucose concentrations is usually remarkably predictable and reproducible [52].

As in adults with type 2 diabetes, adults with type 1 diabetes are encouraged to perform at least 150 minutes of moderate-intensity aerobic exercise per week [35]. In the absence of contraindications (eg, moderate to severe proliferative retinopathy), patients should be encouraged to perform resistance training (exercise with free weights or weight machines) at least twice per week. (See 'A program for physical activity' below.)

PREVENTION OF TYPE 2 DIABETES — In addition to the benefits of exercise in patients with diabetes, exercise may help prevent type 2 diabetes in patients at risk. The data supporting this conclusion are presented separately. (See "Prevention of type 2 diabetes mellitus", section on 'Exercise'.)

A PROGRAM FOR PHYSICAL ACTIVITY — Exercise is recommended for adults with type 1 and type 2 diabetes to improve glycemic control, assist with weight maintenance, and reduce the risk of cardiovascular disease and overall mortality [53]. There is no one exercise prescription for all individuals. Adults with diabetes are encouraged to perform 30 to 60 minutes of moderate-intensity aerobic activity (40 to 60 percent maximal oxygen uptake [VO₂max]) on most days of the week (at least 150 minutes of moderate-intensity aerobic exercise per week). In the absence of contraindications (eg, moderate to severe proliferative retinopathy), people with type 1 and 2 diabetes should also be encouraged to perform resistance training (exercise with free weights or weight machines) at least twice per week. As an alternative for physically fit patients, a shorter duration of more vigorous aerobic exercise (75 minutes per week of jogging 9.6 km/hour) may be preferable [1].

Evaluation prior to recommending an exercise regimen — It is well established that sudden exercise in sedentary subjects can precipitate myocardial infarction [54-56]. We typically perform a physical examination and a resting electrocardiogram (ECG) in sedentary adults (age >50 years) with diabetes prior to beginning an exercise program. There are no randomized trial data to support the routine performance of exercise stress testing in asymptomatic patients with diabetes who are planning to begin an exercise program [1,35]. The vast majority of patients, particularly those with a sedentary lifestyle, are encouraged to begin a gentle exercise program and to gradually progress to a more vigorous program as tolerated. In addition, all cardiovascular disease risk factors (dyslipidemia, hypertension, smoking) should be evaluated and treated. Exercise stress testing for asymptomatic individuals at low risk of coronary artery disease is not necessary [1,35]. However, it may be indicated for asymptomatic individuals at high risk for coronary heart disease (eg, evidence of peripheral or carotid atherosclerotic vascular disease, renal disease, abnormal resting ECG, multiple diabetes complications). The decision to perform stress testing prior to beginning an exercise program should be individualized.

We do not typically perform exercise stress testing in asymptomatic patients as long as they are beginning a gentle exercise program with gradual progression as tolerated. However, the increased risk for asymptomatic coronary artery disease in those with diabetes and other risk factors suggests that an exercise tolerance test be considered prior to changing exercise levels in patients with diabetes who also have peripheral or carotid or coronary artery disease. (See "Overview of general medical care in nonpregnant adults with diabetes mellitus", section on 'Screening for coronary heart disease'.)

Type and frequency of exercise — Some form of regular exercise is likely to be beneficial in most patients with diabetes, even those with advanced, longstanding disease. We encourage patients with diabetes to perform 30 to 60 minutes of moderate-intensity aerobic activity on most days of the week. To increase compliance, the clinician should help the patient choose a type of exercise he or she will enjoy and offer regular encouragement and suggestions for overcoming barriers to exercise [44,45]. A reasonable initial regimen is 10 minutes of stretching and warm-up, followed by 20 minutes of gentle aerobic exercise such as walking, cycling, or rowing. The exercise should be performed regularly (at least three to five times per week) and preferably at the same time in relation to meals and insulin injections in patients treated with insulin. The duration and intensity of exercise should be increased gradually, as tolerated by the patient, to achieve a moderate intensity (eg, brisk walking). In the absence of contraindications (eg, moderate to severe proliferative retinopathy), people with type 1 and 2 diabetes should also be encouraged to perform resistance training (exercise with free weights or weight machines) at least twice per week. The exercises should include the large muscles of the core, upper, and lower body (approximately 10 repetitions per set).

Similar benefits may be achieved with 75 minutes per week of more vigorous aerobic exercise (jogging 9.6 km/hour) [1]. This type of regimen may be an option for adults with diabetes who are generally fit and have higher aerobic capacity. Even shorter bouts of higher-intensity exercise (>75 percent VO₂max) have been advocated by some experts [57]. With low-volume, high-intensity training, patients exercise more vigorously but for a reduced amount of time. An example of a low-volume, high-intensity training program is cycling at 90 percent of individual maximal heart rate for 60 seconds, followed by 60 seconds of rest, repeated 10 times (total training session 20 minutes with 10 minutes of cycling and 10 minutes resting) [5]. The long-term health effects of low-volume, high-intensity training are unknown. This type of exercise regimen should only be used in adults who have been regularly exercising. Patients who are initiating an exercise program should begin with a gentle exercise program as described above with gradual progression as tolerated.

The type of exercise may be limited by the presence of microvascular complications. There are occasional reports of patients with proliferative retinopathy developing retinal bleeding during vigorous exercise (involving Valsalva maneuvers), which have led many clinicians to advise caution with regard to intense isometric exercise (such as weight lifting) that can cause a marked increase in blood pressure that might precipitate intraocular bleeding in such patients [1]. Vigorous exercise of any type should be avoided in patients with recent or active retinal bleeding. Patients with neuropathy should avoid traumatic weightbearing exercise (long-distance running or prolonged downhill skiing), which may precipitate stress fractures in the small bones of the foot and ankle and the development of pressure ulcers on the toes and feet. Well-fitting protective footwear and comfortable shoes are also needed. Although exercise can transiently increase urinary protein excretion, there is no evidence that exercise increases progression of chronic kidney disease [35]. Thus, people with chronic kidney disease may engage in aerobic and resistance exercise, as long as the exercise is started at a low intensity and volume and slowly increased as tolerated [1]. (See "Uremic myopathy and deconditioning in patients with chronic kidney disease (including those on dialysis)".)

The American Heart Association, the American Diabetes Association, and the American College of Sports Medicine recommend at least 150 minutes of moderate-intensity aerobic activity (40 to 60 percent of VO₂max) per week for patients with diabetes [1,35,53]. The activity should be distributed over at least three days each week, with no more than two consecutive days of inactivity. A larger amount of exercise (seven hours per week) may be beneficial for long-term maintenance of weight loss. Resistance training should be performed at least twice weekly [1,35]. The US Department of Health and Human Services' Physical Activity Guidelines for Americans suggest that adults do 150 minutes/week of moderate intensity, or at least 75 minutes of vigorous-intensity aerobic exercise per week or combination of the two [58]. They suggest that adults with chronic conditions follow the guidelines when possible and, if not possible, engage in regular physical activity according to their abilities.

Managing blood glucose during exercise — For patients who take insulin (particularly those with type 1 diabetes), adjustments of their insulin regimen before, during, and after exercise are often empiric and aided by the results of self-monitoring of blood glucose. Vigorous exercise should be avoided in the presence of substantial hyperglycemia (≥250 mg/dL [13.9 mmol/L]) or ketosis [15]. It is not necessary to defer exercise based on milder hyperglycemia, as long as the patient feels well and there is no ketonemia or ketonuria. For insulin-requiring patients and for those taking insulin secretagogues (sulfonylureas, glinides), general considerations include:

●Fluid intake should be maintained at a relatively high level before, during, and after exercise.

●Measure the blood glucose before, during, and after exercise so that the changes in blood glucose can be documented and then predicted for subsequent exercise sessions [52]. (See "Cases illustrating the effects of exercise in intensive insulin therapy for type 1 diabetes mellitus", section on 'Case 2'.)

●If the pre-exercise blood glucose is <100 mg/dL (5.6 mmol/L), ingest extra food, in the form of 15 to 30 grams of quickly absorbed carbohydrate (such as glucose tablets, hard candies, or juice), which should be taken 15 to 30 minutes before exercise and approximately every 30 minutes during exercise, based on repeat blood glucose testing during the exercise. Patients are also at risk of late hypoglycemia (ie, four to eight hours after the termination of exercise) due to replenishment of depleted glycogen stores. This can usually be avoided by ingesting slowly absorbed carbohydrates (dried fruit, fruit jerky, granola bars, or trail mix) immediately after exercise [59]. (See "Cases illustrating the effects of exercise in intensive insulin therapy for type 1 diabetes mellitus", section on 'Case 3'.)

Inadequate replacement of carbohydrate before, during, and after exercise is the most common cause of exercise-associated hypoglycemia in patients taking insulin [60]. (See "Hypoglycemia in adults with diabetes mellitus", section on 'Exercise-induced hypoglycemia'.)

●Hypoglycemia is uncommon in patients with type 2 diabetes not treated with insulin or insulin secretagogues (sulfonylureas, glinides), and therefore, ingestion of extra carbohydrates is not typically required.

Additional considerations for insulin-requiring patients include:

●Decrease the insulin dose that affects time of the day when exercise will be performed by approximately 30 percent. This is especially important if exercise is of long duration (more than 60 minutes) [60].

●To prevent increased insulin absorption, inject the insulin in a site other than the muscles to be exercised [16]. As an example, the arm is a suitable site for cycling. On the other hand, the abdomen is preferred with tennis or racquetball where the exercise involves both the arms and legs. (Although absorption of insulin from the abdomen is faster than from the arm or leg in the resting state [61], this difference is reversed with exercise.) It is also prudent to administer the insulin 60 to 90 minutes before exercise to minimize the problem of increased absorption.

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Diabetes mellitus in adults".)

INFORMATION FOR PATIENTS — UpToDate offers two types of patient education materials, "The Basics" and "Beyond the Basics." The Basics patient education pieces are written in plain language, at the 5^th to 6^th grade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10^th to 12^th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.

Here are the patient education articles that are relevant to this topic. We encourage you to print or e-mail these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on "patient info" and the keyword(s) of interest.)

●Basics topics (see "Patient education: Type 1 diabetes (The Basics)" and "Patient education: Type 2 diabetes (The Basics)")

●Beyond the Basics topics (see "Patient education: Type 1 diabetes: Overview (Beyond the Basics)" and "Patient education: Type 2 diabetes: Overview (Beyond the Basics)" and "Patient education: Preventing complications from diabetes (Beyond the Basics)")

SUMMARY AND RECOMMENDATIONS

●In adults with diabetes, regular exercise is important to improve glycemic control, assist with weight maintenance, and reduce the risk of cardiovascular disease and overall mortality. (See 'Long-term effects in type 2 diabetes' above and 'Long-term effects in type 1 diabetes' above and 'A program for physical activity' above.)

●The vast majority of adults, particularly those with a sedentary lifestyle, are encouraged to begin a gentle exercise program and to gradually progress to a more vigorous program as tolerated. In addition, all cardiovascular disease risk factors (dyslipidemia, hypertension, smoking) should be evaluated and treated. (See 'Evaluation prior to recommending an exercise regimen' above.)

●We do not typically perform exercise stress testing in asymptomatic patients as long as they are beginning a gentle exercise program with gradual progression as tolerated. However, the increased risk for asymptomatic coronary artery disease in those with diabetes and other risk factors suggests that an exercise tolerance test be considered prior to changing exercise levels in patients with diabetes who also have peripheral or carotid or coronary artery disease. (See 'Evaluation prior to recommending an exercise regimen' above.)

●Adults with diabetes are encouraged to perform at least 150 minutes of moderate-intensity (eg, brisk walking) aerobic exercise per week. In the absence of contraindications (eg, moderate to severe proliferative retinopathy), people with type 1 and 2 diabetes should also be encouraged to perform resistance training (exercise with free weights or weight machines) at least twice per week. For adults with diabetes who are generally fit and have higher aerobic capacity, a shorter duration of more vigorous aerobic exercise (75 minutes per week of jogging 9.6 km/hour) may be preferable. (See 'Type and frequency of exercise' above.)

●Vigorous exercise should be avoided in the presence of ketosis. However, it is not necessary to defer exercise based on mild hyperglycemia (<250 mg/dL [13.9 mmol/L]), as long as the patient feels well and there is no ketonemia or ketonuria. (See 'Managing blood glucose during exercise' above.)

●Fluid intake should be maintained at a relatively high level before, during, and after exercise. (See 'Managing blood glucose during exercise' above.)

●For patients who take insulin (particularly those with type 1 diabetes), adjustments of their insulin regimen before, during, and after exercise are often empiric and aided by the results of self-monitoring of blood glucose. For patients who take insulin or insulin secretagogues (sulfonylureas, glinides), blood glucose should be measured before, during, and after exercise so that the changes in blood glucose can be documented and then predicted for subsequent exercise sessions. (See 'Managing blood glucose during exercise' above.)

●If the pre-exercise blood glucose is <100 mg/dL (5.6 mmol/L), insulin- or insulin secretagogue-treated patients should ingest extra food, in the form of 15 to 30 grams of quickly absorbed carbohydrate (such as glucose tablets, hard candies, or juice), which should be taken 15 to 30 minutes before exercise and approximately every 30 minutes during exercise, based on repeat blood glucose testing during the exercise. Such patients are also at risk of late hypoglycemia (ie, four to eight hours after the termination of exercise) due to replenishment of depleted glycogen stores. (See 'Managing blood glucose during exercise' above.)

●Hypoglycemia is uncommon in patients with type 2 diabetes not treated with insulin or insulin secretagogues (sulfonylureas, glinides), and therefore, ingestion of extra carbohydrates is not typically required. (See 'Managing blood glucose during exercise' above.)

ACKNOWLEDGMENT — The UpToDate editorial staff acknowledges David McCulloch, MD, who contributed to an earlier version of this topic review.