Exercise testing in young asymptomatic diabetic patients.

The cardiovascular response to submaximal bicycle exercise was studied in a group of 19 asymptomatic diabetic patients aged 18 to 39, including 11 males and 8 females and 18 control subjects (9 males and 9 females, aged 20 to 34 years). The maximum heart rate achieved by the control subjects (group I), 175.9 +/- 8.9 beats/min, was greater than that achieved by the diabetic patients (group II), 159.4 +/- 17.8 beats/min, (P less than 0.01). The work load at which the maximum heart rate was reached was lower in diabetic males, 681 +/- 155.4 kg m/min, than in healthy males, 866.7 +/- 139.9 kg m/min, (P less than 0.02). Although systolic blood pressure elevations were comparable during exercise and the postexercise period, the increase in diastolic blood pressure during exercise in the diabetic patients was greater than in control subjects (P less than 0.001). This difference, however, was only observed in the males and not in the females. The difference in diastolic blood pressure was again noted between the groups in the postexercise period; that of group II was higher than that of group I (P less than 0.01). This was particularly notable in the older diabetics (aged 31 to 40 years). One patient in group II developed ischemic ST segment changes, and 1 subject in each group was found to have J junction depression of 1.0 mm or more. The implications of these findings are discussed in relation to the possible pathophysiology of the diabetic patients.