At a glance
- Exercise has demonstrable benefits for cardiovascular risk factors of concern in type 2 diabetes mellitus.
- Standard exercise stress testing is recommended before initiating a vigorous fitness program.
- Physical activity should be initiated gradually in previously sedentary individuals.
- Active people are less prone to foot ulceration.
The increasing prevalence of type 2 diabetes mellitus (T2DM) and the threat of an epidemic of its complications have led the American Heart Association to issue a scientific statement on a key but often overlooked element of T2DM management: exercise.
“We want to emphasize that exercise is just as important, if not more important, as giving antihypertensive medication, hypoglycemic medication, or a statin,” says Roger S. Blumenthal, MD, director of the Johns Hopkins Ciccarone Preventive Cardiology Center in Baltimore and an author of the statement.
Regular exercise has been shown to improve glycemic control, presumably through reduced body fat, heightened insulin sensitivity, and enhanced glucose transporter function. Gains in muscle mass and blood flow may also play a role, the guidelines suggest. More generally, exercise has demonstrable benefits for cardiovascular risk factors of concern in T2DM, such as hypertension, hyperlipidemia, and obesity.
The authors advocate the inclusion of exercise in prevention counseling as part of every clinical encounter with T2DM patients and suggest that the primary-care setting is “the logical first location for education” in this area.
The guidelines address exercise training in terms of duration, frequency, and intensity as well as such ancillary concerns as cardiovascular and other risks and adherence. One often misunderstood issue that deserves special attention, Dr. Blumenthal notes, is preparticipation testing.
When and how to test
While major cardiac events during exercise are generally rare, the imposition of screening for occult coronary artery disease may pose a barrier to exercise, particularly in obese and out-of-shape individuals. “The overall balance of benefit in exercise substantially exceeds the risk in unselected subjects,” the guidelines state.
The presence of T2DM does not change that equation. “Many clinicians, especially in private practice, think that if a patient has diabetes, you have to do stress nuclear testing,” explains Dr. Blumenthal. “There’s no basis for that at all.”
Standard exercise stress testing (with echocardiography, if imaging is indicated) is more broadly useful, and the guidelines recommend this before initiating a vigorous fitness program. When more moderate exercise is planned, testing may be more selective, generally targeting individuals with stable coronary artery disease who have not been tested for two years, those who experience chest discomfort or dyspnea, or those exhibiting an abnormal ECG or clinical or laboratory evidence of peripheral artery disease or cerebrovascular disease.
Treadmill testing is most useful. Results can be used to help design an exercise program. For example, a patient with ischemia at a high workload might be prescribed a protocol that maintains a heart rate at least 10 beats/minute below the ischemic threshold. Stress imaging and pharmacologic stress testing are indicated in specified circumstances.