AEROBIC EXERCISE CAPACITY REMAINS NORMAL DESPITE IMPAIRED ENDOTHELIALFUNCTION IN THE MICROCIRCULATION AND MACROCIRCULATION OF PHYSICALLY ACTIVE IDDM PATIENTS

The aim of the present study was to examine if diabetes in the absence of neuropathy affects the exercising capacity of IDDM patients, and w hether regular, intense training has a beneficial effect on endothelia l function. Five groups of subjects were studied: 23 healthy control s ubjects who exercised regularly (age 33 +/- 6 years), 23 nonneuropathi c type 1 diabetic patients who exercised regularly (age 33 +/- 6 years , IDDM duration II +/- 8 years), 7 neuropathic type 1 diabetic patient s who exercised regularly (age 36 +/- 7 years, IDDM duration 22 +/- 8 years), 18 healthy subjects who did not exercise regularly (age 34 +/- 7 years), and 5 nonneuropathic type 1 diabetic patients who did not e xercise regularly (age 31 +/- 4 years, IDDM duration 20 +/- 3 years). All groups mere matched for age, sex, and body weight. No differences existed in the energy expenditure per week in physical activity among the three exercising groups or between the two nonexercising groups. T he maximal oxygen uptake was similar between control and diabetic nonn europathic exercisers, and among diabetic neuropathic exercisers, cont rol nonexercisers, and diabetic nonexercisers; however, a significant difference existed between the first two and the last three groups (P < 0.0001). A stepwise increase was found in the resting heart rate amo ng the groups, ranging from the lowest in control exercisers to the hi ghest in diabetic nonexercisers, but the maximal heart rate was lower only in diabetic neuropathic exercisers compared with all other groups (P < 0.05). Assessments of endothelial function in both macro-and mic rocirculation were performed in 12 control exercisers, 10 diabetic non neuropathic exercisers, 5 diabetic neuropathic exercisers, 17 control nonexercisers, and 4 diabetic nonexercisers. When all diabetic patient s mere considered as one group and all control subjects as another, th e microcirculation endothelial function in the diabetic group was redu ced compared with the control subjects (91 +/- 49 vs. 122 +/- 41% flux increase over baseline; P < 0.05). In contrast, no differences existe d among the three diabetic groups or between the two control groups. S imilarly, in macrocirculation, a reduced response during reactive hype remia was observed in the diabetic patients compared with control subj ects (7.0 +/- 4.5 vs. 11.2 +/- 6.6% diameter increase; P < 0.05), wher eas again no difference existed among the three diabetic groups or bet ween the two control groups. These data suggest that diabetes per se d oes not affect aerobic exercise capacity (Vo(2max)) in physically acti ve individuals, but is reduced in the presence of neuropathy. In addit ion, regular exercise training involving the lower extremities does no t improve the endothelial function in the micro-and macrocirculation o f the nonexercised upper extremity in type 1 diabetic patients.