Nerve Function and Metabolic Control in Teenage Diabetics

Peripheral somatic and autonomic nerve function have been studied in 79 teenage (16–19 yr) diabetics and 20 age- and sex-matched normal controls. Almost three-quarters of the diabetics (72%) had abnormal peripheral somatic nerve function tests, and one-third (31%) had abnormal cardiac parasympathetic tests. Both motor and sensory peripheral somatic nerve abnormalities were related to poor prevalling glycemic control (HbA₁) and duration of diabetes. Thus, the 27 patients with three or more (maximum six) peripheral nerve abnormalities had significantly higher HbA₁ levels (P < 0.001) and longer duration of diabetes (P < 0.01) than the 22 with no abnormalities. Individual peripheral somatic nerve tests almost invariably correlated only with HbA₁ (median motor, P < 0.05; peroneal motor, P < 0.001; sural sensory, P < 0.001) or duration of diabetes (median sensory, P < 0.001). Sensory potential amplitude, as well as conduction velocity, was frequently reduced, implying axonal involvement. These findings suggest that abnormal peripheral and autonomic nerve function are common in young insulin-dependent diabetics and that poor metabolic control is a major determinant of the damage.