Diabetic neuropathy as a heterogeneous syndrome: multivariate analysis of clinical and neurological findings.

We quantitatively assessed peripheral and autonomic nerve function in diabetic patients and compared them with various parameters of their diabetic status. Motor and sensory nerve conduction velocity (MCV, SCV), vibratory perception threshold (VPT) and the coefficient of variation of the ECG R-R interval (CV R-R) were measured in 85 diabetic patients aged 20-59 years. These values were compared with those of age-matched healthy subjects. Moreover, in 53 patients, MCV, SCV, VPT and CV R-R were investigated by multivariate analysis in relation to clinical parameters. In diabetics, MCV, SCV and CV R-R were significantly lower and VPT was higher than in age-matched healthy controls. The prevalence of impaired values in diabetics was 70% for VPT in the toe, 60% for SCV, and 55% for MCV, CV R-R and VPT in the finger. Impairments of MCV, SCV, CV R-R and VPT were closely correlated with diabetic retinopathy, proteinuria and duration of disease. Categorical regression analysis (multivariate analysis) revealed that the impairment of conduction velocity was closely related to diabetic retinopathy and to hypo- or areflexia, that the impairment of the vibratory perception threshold was related to ischemic changes in ECG and to hypo- or areflexia, and that the reduction of CV R-R was related to orthostatic hypotension and to proteinuria. These findings suggest that diabetic neuropathy progresses in parallel with other complications, and that it is a heterogeneous syndrome rather than a single entity.