Cardiovascular effects of diabetic autonomic neuropathy include postural hypotension, resting tachycardia, and, possibly, painless myocardial infarction. Involvement of cardiovascular reflexes in diabetes can be assessed using simple noninvasive tests: the Valsalva maneuver, beat-to-beat heart rate variation, the heart rate response to standing, postural fall in blood pressure, and the sustained handgrip test. Tests of parasympathetic function appear to be abnormal more frequently and earlier in cardiac autonomic involvement, whereas sympathetic damage usually occurs later and is associated with clinical symptoms. When test results are abnormal, in association with symptoms suggestive of autonomic neuropathy, the prognosis is grave. Some sudden deaths that occur may be due to abnormal autonomic reflexes.