Epidemiological correlates of diabetic neuropathy. Report from Pittsburgh Epidemiology of Diabetes Complications Study

Abstract

The natural history of diabetic neuropathy and its risk factors are not well understood, apart from the recognition that prevalence increases with duration and, in many studies, degree of glycemia. The role of potential risk factors was therefore evaluated in a cross-sectional analysis from the baseline examination of the Pittsburgh Epidemiology of Diabetes Complications Study. We present results from the first 400 subjects seen at baseline examination. Neuropathy was determined by a trained internist with a standardized examination and was defined as the presence of at least two of three criteria: abnormal sensory or motor signs, symptoms consistent with neuropathy, and decreased tendon reflexes. The prevalence of neuropathy in this cohort was 34% (18%, 18-29 yr old, 58% ≥30 yr old) with no difference by sex. By focusing on subjects s 18 yr old, all significant univariate variables (e.g., duration, glycosylated hemoglobin [HbAJ) were analyzed in 3 multiple logistic regression models: all subjects ≥18 yr old and separating the same subjects into two groups based on age (18-29 and 2:30 yr). Duration, HbA₁, smoking status, and high-density lipoprotein cholesterol were found to be associated with neuropathy in the models for the ≥18-yr-old group and the ≥30-yr-old group. In the 18- to 29-yr-old group, duration, HbA₁, and hypertension status were found to be significantly associated with neuropathy. There was a univariate association of neuropathy with macrovascular disease, nephropathy, and retinopathy. Macrovascular disease, although borderline significant, remained in the original logistic model for the ≥18-yr-old subjects. The addition of either retinopathy or nephropathy to the original logistic model for the 18- to 29-yr-old subjects resulted in a statistically significantly improved fit (of model to data), suggesting that these complications may be a marker for something beyond the risk factors described. The results suggest that traditional cardiovascular risk factors (e.g., lipids and smoking) are important determinants of distal symmetric polyneuropathy and if confirmed in prospective follow-up, open new avenues to the prevention of diabetic neuropathy.