Auditory brainstem latencies in type I (insulin-dependent) diabetic patients.

INTRODUCTION: This study was undertaken to compare auditory brainstem response latencies in insulin-dependent diabetics, and to compare these findings with metabolic control, microangiopathy, neuropathy, and the duration of diabetes.
METHODS: Auditory brainstem latencies were studied in 53 type I diabetic patients and 42 randomly selected nondiabetic control subjects, aged between 20 and 40 years. Three different stimulus repetition rates (10, 30, and 50 Hz) were used. All subjects had normal hearing ability.
RESULTS: Wave V latencies were longer in diabetic patients when compared with those of control subjects at all repetition rates. At repetition rates of 10 and 50 Hz, diabetic patients had a prolonged I-V interwave latency, and at a repetition rate of 50 Hz, diabetics had a longer III-V interwave latency than control subjects. These findings indicate a central disturbance in the auditory pathway. Microvascular complications (retinopathy, nephropathy) and the duration of diabetes were associated with the prolongation of auditory brainstem latencies. In contrast, poor metabolic control (high fasting blood glucose and glycated hemoglobin A1c) at the time of the present study was only marginally associated with prolonged auditory brainstem latencies. The changes in auditory brainstem latencies associated with diabetic neuropathy (measured with five cardiac autonomic nervous function tests) appeared simultaneously with microvascular complications and in patients with diabetes of long duration, and thus a causative role of diabetic neuropathy in the pathogenesis of prolonged auditory brainstem latencies remains unsolved.
CONCLUSION: Delayed auditory brainstem latencies in type I diabetic patients are probably caused by the long duration of diabetes and the microvascular complications associated with it.