Peripheral nerve function is increasingly impaired during puberty in adolescents with type 1 diabetes

OBJECTIVE - To evaluate the impact of puberty on peripheral nerve function in adolescents with type 1 diabetes. RESEARCH DESIGN AND METHODS - Of 138 eligible patients with type 1 diabetes , 100 patients (age >9 years and diabetes duration >2 years) attending an o utpatient diabetes clinic and 100 age- and sex-matched healthy control subj ects took part in this cross-sectional study. Peripheral motor and sensory nerve conduction tests, cardiovascular reflex tests on the autonomic nervou s system, and measurements of vibration-perception threshold (VPT) were per formed. RESULTS - Nerve conduction velocity (NCV) in the distal motor and sensory n erves, the motor nerve distal latency, and the sensory nerve action potenti al (SNAP) amplitude were impaired in the adolescent patients with type 1 di abetes. The deterioration in motor NCV, H-reflex latency, and SNAP amplitud e became more conspicuous in late puberty and postpuberty and was related t o poor metabolic control. A total of 10 patients had distal diabetic polyne uropathy (Dr) neurophysiologically, and these patients had significantly lo wer heart-rate variation in the deep breathing test than the other patients . Three of the patients with DP had peripheral neurological signs or sympto ms. A slight difference in the WT between the patients and control subjects was observed after puberty. CONCLUSIONS - Increasing subclinical motor nerve impairment can be detected during late puberty and after puberty, and sensory NCV and SNAP amplitude are reduced in adolescents with type 1 diabetes. Poor metabolic control dur ing puberty appears to induce deteriorating peripheral neural function in y oung patients with type 1 diabetes.