Abstract

Six juvenile diabetics (age, 31 +/- 2 yr (x and SEM) duration of diabetes, 15 +/- 4 yr), who showed signs of autonomic neuropathy (decreased beat-to-beat variation in heart rate during deep breathing), and seven control patients of similar age (27 +/- 1 yr) and duration of diabetes (14 +/- 2 yr) performed graded exercise on an ergometer cycle 3 h after breakfast and subcutaneous administration of insulin. Plasma epinephrine increased significantly in both patients groups and was not significantly different at exhaustion (0.43 +/- 0.17 ng/ml (neuropathy) vs. 1.07 +/- 0.28 ng/ml (controls), (P< 0.1). Plasma norepinephrine levels increased significantly in controlpatients but not in autonomic neuropathy, and they were significantly different at exhaustion (1.43 +/- 0.34 ng/ml (neuropathy) vs. 2.51 +/- 0.26 ng/ml (controls), P<0.05). The relationships between plasma norepinephrine and epinephrine levels, respectively, and relative work load (expressed as oxygen uptake-in percent-of individual maximal oxygen uptake) were shifted to the right in patients with autonomic neuropathy, indicating impaired sympathetic activity. In conclusion, diabetics with decreased beat-to-beat variation in heart rate displayed impaired responses of catecholamines, indicating a defective sympathoadrenal outflow, and of other glucoregulatory hormones during graded exercise. Verf.-Referat (gekuerzt)