LONG-TERM HYPERGLYCEMIA IS RELATED TO PERIPHERAL-NERVE CHANGES AT A DIABETES DURATION OF 4 YEARS

OBJECTIVE - To examine longitudinal hyperglycemia and peripheral nerve responses in a population-based incident cohort. RESEARCH DESIGN AND METHODS - A sample from an incident cohort of young people was compreh ensively followed from diagnosis of IDDM. Participants were invited to submit blood samples three times per year for central testing of GHb. During their 4th year of diabetes. nerve conduction studies were perf ormed on the median sensory and motor, peroneal motor, and sural senso ry nerves. Relationships between mean GHb and nerve latencies, velocit ies, and amplitudes were explored. RESULTS - GHb was positively relate d to all nerve latencies and negatively related to all nerve velocitie s, The relationships between mean GHb and nerve conduction latencies a nd velocities differed by sex for the peroneal nerve latency (beta = 0 .17 male subjects, beta = -0.01 female subjects; P < 0.001). Pubertal participants had lower velocities and longer latencies than prepuberta l participants (beta = 0.37; P = 0.05 peroneal latency), after adjustm ent for GHb, height, and extremity temperature. Sensory and motor nerv e amplitudes were related to Gl-lb. and these relationships did not di ffer by sex. CONCLUSIONS - Our stud indicates that sustained hyperglyc emia is related to functional changes, at the minimum, in peripheral s ensory and motor nerve conduction at a diabetes duration of 4 years. O ur findings are consistent with a dying-back neuropathy and there is s ome suggestion that chronic hyperglycemia may be more detrimental to n erves in male subjects than in female subjects.