The Medical Evaluation of Patients with Diabetes Mellitus in Exercise Therapy

Abstract

To investigate myocardial ischemia during exercise, submaximal exercise testing with electrocardiogram and thallium 201-myocardial scintigraphy was performed in non-insulin-dependent diabetics. The relationship between plasma atrial natriuretic polypeptide (ANP) levels in response to exercise and cardiac function assessed by echocardiography was also examined. The following results were obtained: 1) Twelve of the 66 diabetics (18.2%) had ischemic ST-segment changes in exercise ECGs, compared with 4 of 75 control subjects (5.3%)(p less than 0.05). Of the 12 diabetics with positive exercise ECGs, 10 were asymptomatic. 2) The washout rate in thallium-201 myocardial scintigraphy was significantly less in diabetics with positive exercise ECGs (36.5 +/- 4.1%) than in controls (51.9 +/- 2.8%)(p less than 0.05). 3) Although no difference in heart rate were observed between diabetics and controls, diabetic patients had significantly higher systolic blood pressure than controls during all stages of exercise and at maximal exertion. Rate pressure products in stages 1 and 2 were significantly higher in diabetics than in controls. 4) The increase of plasma ANP concentration during moderate exercise (VO2 max 60%) was significantly greater in diabetics than in controls (32.3 +/- 11.9 pg/ml vs. 15.0 +/- 1.7 pg/ml)(p less than 0.02). 5) There was a significant correlation between the increase in plasma ANP during exercise and the levels of left ventricular diastolic function (A/R:r = 0.504, p less than 0.05, IRT:r = 0.587, p less than 0.02), assessed by echocardiography, in diabetics. In conclusion, this study demonstrated that the frequency of asymptomatic myocardial ischemia during exercise was higher in diabetics than in controls.(ABSTRACT TRUNCATED AT 250 WORDS)