Safe exercise participation can be complicated by the presence of diabetes-related health complications such as CVD, hypertension, neuropathy, or microvascular changes (239
). For individuals desiring to participate in low-intensity PA such as walking, health care providers should use clinical judgment in deciding whether to recommend preexercise testing (3
). Conducting exercise stress testing before walking is unnecessary. No evidence suggests that it is routinely necessary as a CVD diagnostic tool, and requiring it may create barriers to participation.
For exercise more vigorous than brisk walking or exceeding the demands of everyday living, sedentary and older diabetic individuals will likely benefit from being assessed for conditions that might be associated with risk of CVD, contraindicate certain activities, or predispose to injuries, including severe peripheral neuropathy, severe autonomic neuropathy, and preproliferative or proliferative retinopathy (240
). Before undertaking new higher-intensity PA, they are advised to undergo a detailed medical evaluation and screening for BG control, physical limitations, medications, and macrovascular and microvascular complications (3
This assessment may include a graded exercise test depending on the age of the person, diabetes duration, and the presence of additional CVD risk factors (3
). The prevalence of symptomatic and asymptomatic coronary artery disease (CAD) is greater in individuals with type 2 diabetes (72
), and maximal graded exercise testing can identify a small proportion of asymptomatic persons with severe coronary artery obstruction (52
Most young individuals with a low CAD risk may not benefit from preexercise stress testing. In the Look AHEAD trial, although exercise-induced abnormalities were present in 1,303 (22.5%) participants, only older age was associated with increased prevalence of all abnormalities during maximal testing (52
). A systematic review of the U.S. Preventive Services Task Force (USPSTF) concluded that stress testing should not be routinely recommended to detect ischemia in asymptomatic individuals with a low CAD risk (<10% risk of a cardiac event more than 10 years) because the risks from invasive testing done after a false-positive test outweigh the benefits of its detection (79
). The lower the CAD risk, the higher the chance of a false positive (79
Current guidelines attempt to avoid automatic inclusion of lower-risk individuals with type 2 diabetes, stating that exercise stress testing is advised primarily for previously sedentary individuals with diabetes who want to undertake activity more intense than brisk walking. The goal is to more effectively target individuals at higher risk for underlying CVD (239
). The UKPDS Risk Engine (http://www.dtu.ox.ac.uk/riskengine/download.htm
) can also be used to calculate expected 10-year CV risk based on age, sex, smoking, A1C, diabetes duration, lipids, BP, and race.
In general, electrocardiogram (ECG) stress testing may be indicated for individuals matching one or more of these criteria:
- Age >40 years, with or without CVD risk factors other than diabetes
- Age >30 years and
- Type 1 or type 2 diabetes of >10 years in duration
- Cigarette smoking
- Proliferative or preproliferative retinopathy
- Nephropathy including microalbuminuria
- Any of the following, regardless of age
- Known or suspected CAD, cerebrovascular disease, and/or peripheral artery disease (PAD)
- Autonomic neuropathy
- Advanced nephropathy with renal failure
Use of these criteria does not exclude the possibility of conducting ECG stress testing on individuals with a low CAD risk or those who planning to engage in less intense exercise (248
). In the absence of contraindications to maximal stress testing, it can still be considered for anyone with type 2 diabetes. Although clinical evidence does not definitively determine who should undergo such testing, potential benefits should be weighed against the risk associated with unnecessary procedures for each individual (155
In individuals with positive or nonspecific ECG changes in response to exercise, or with nonspecific ST- and T-wave changes at rest, follow-up testing may be performed (236
). However, the DIAD trial involving 1,123 individuals with type 2 diabetes and no symptoms of CAD found that screening with adenosine-stress radionuclide myocardial perfusion imaging for myocardial ischemia more than 4.8 years did not alter rates of cardiac events (288
); thus, the cost-effectiveness and diagnostic value of more intensive testing remains in question.
There is no evidence available to determine whether preexercise evaluation involving stress testing is necessary or beneficial before participation in anaerobic or resistance training. At present, most testing centers are equipped for maximal stress testing but not for an alternate form of testing involving resistance exercise. Moreover, coronary ischemia is less likely to occur during resistance compared with aerobic exercise eliciting the same heart rate (HR), and some doubt exists as to whether resistance exercise induces ischemia (77
). A review of 12 studies of resistance exercise in men with known CAD found no angina, ST depression, abnormal hemodynamics, ventricular dysrhythmias, or other complications during such exercise (275
Before undertaking exercise more intense than brisk walking, sedentary persons with type 2 diabetes will likely benefit from an evaluation by a physician. ECG exercise stress testing for asymptomatic individuals at low risk of CAD is not recommended but may be indicated for higher risk. ACSM evidence category C. ADA C level recommendation.