Nerve function and its determinants in patients with newly-diagnosed type 2 (non-insulin-dependent) diabetes mellitus and in control subjects--a 5-year follow-up.

In order to assess the changes in nerve function 5 years after the diagnosis of diabetes mellitus and the determinants of progression of neuropathy, we studied 113 Type 2 (non-insulin-dependent) diabetic patients and 127 non-diabetic control subjects. Motor and sensory nerve conduction velocities were measured at the time of diagnosis of diabetes and 5 years later. At both examinations conduction velocities and response amplitudes were lower in diabetic patients than in control subjects. During the follow-up sural nerve conduction was impaired in both diabetic and control subjects, but, in general, changes in neurophysiological parameters were slight and inconsistent. In 12 diabetic patients nerve function deteriorated significantly during the follow-up. These patients had higher glycaemic indices at both examinations and lower baseline blood pressure levels as compared to the rest of the diabetic patients. No differences between these patient groups were found in other baseline risk factors (age, obesity, use of alcohol, smoking, serum insulin levels, albuminuria, lipids). In conclusion, Type 2 diabetic patients have disturbed nerve function at the time of diagnosis, but neurophysiological impairment during the next 5 years is on the average slight. Poor glycaemic control seems to be the most important risk factor in the deterioration of nerve function in these patients.