A cross-sectional multicentre study of randomly selected diabetic patients was performed using a standardised questionnaire and examination, to establish the prevalence of peripheral neuropathy in patients attending 118 hospital diabetes clinics in the UK. Vibration perception threshold was performed in two centres to compare with the clinical scoring systems. A total of 6487 diabetic patients were studied. 53.9% male, median age 59 years (range 18-90 years). 37.4% Type 1 (insulin-dependent) diabetes mellitus, with a median duration of diabetes 8 years (0-62 years). The overall prevalence of neuropathy was 28.5% (27.4-29.6%) (95% confidence interval) in this population. The prevalence in Type 1 diabetic patients was 22.7% (21.0-24.4%) and in Type 2 (non-insulin-dependent) diabetic patients it was 32.1% (30.6-33.6%). The prevalence of diabetic peripheral neuropathy increased with age, from 5% (3.1-6.9%) in the 20-29 year age group to 44.2% (41.1-47.3%) in the 70-79 year age group. Neuropathy was associated with duration of diabetes, and was present in 20.8% (19.1-22.5%) of patients with diabetes duration less than 5 years and in 36.8% (34.9-38.7%) of those with diabetes duration greater than 10 years. Mean vibration perception threshold measured at the great toe was 21.1 +/- 13.5 SD volts and correlated with the neuropathy disability score, r = 0.8 p < 0.001. In conclusion, diabetic peripheral neuropathy is a common complication associated with diabetes. It increases with both age and duration of diabetes, until it is present in more than 50% of Type 2 diabetic patients aged over 60 years.(ABSTRACT TRUNCATED AT 250 WORDS)