Autonomic nerve function in children and adolescents with insulin-dependent diabetes mellitus

Autonomic nerve function was assessed in 67 insulin-dependent diabetic children and adolescents and in 30 control subjects of the same age. The heart rate and blood pressure reactions to a deep breathing test (E/I ratio) and a tilt table test (acceleration and brake indices) were used. The E/I ratio, 1.54 +/- 0.21, and the acceleration index, 25 +/- 7.7, in the diabetic children were not significantly different from those of the control children, 1.51 +/- 0.16 and 24 +/- 7.5, respectively. Neither was any difference observed between the mean brake index values; 24.3 +/- 14.6 vs 23.5 +/- 7.5. However, the variance of the brake index in diabetic children was significantly higher than in control children (P less than 0.005). The brake index was negatively correlated to age in the healthy control children (r = -0.48, P less than 0.1). The acceleration index, but not the E/I ratio, also tended to be age related (r = -0.32, P less than 0.01 NS). No correlation was observed between sex, glycaemic control or duration of diabetes and the autonomic nerve function. Neither were severe hypoglycaemic episodes in diabetic children related to the autonomic nerve function. It is concluded that autonomic neuropathy is uncommon in diabetic children and adolescents and that age-related index values should be used when autonomic nerve function is evaluated in children of different ages.