The development and long term progression of diabetic peripheral neuropathy was studied using vibration perception threshold (VPT) as a validated measure. Three hundred and ninety-two patients had a normal age corrected VPT (12.1 +/- 3.7 volts) at baseline, with an age corrected logarithmic VPTscore < 12. 19.9% developed an abnormal VPT over a 12 year period, increasing from 14.2 +/- 3.7 volts (VPTscore 10.4 +/- 0.6) at baseline to 35.9 +/- 9.5 volts (VPTscore 12.6 +/- 0.45) at follow up (P = 0.0001), and from 10.1 +/- 3.7volts (VPTscore 9.4 +/- 0.8) to 14.2 +/- 4.7 (VPTscore 9.8 +/- 0.8) in the rest. Over 80% thus retained a "normal" VPT after a mean diabetes duration of 16 years despite only average glycaemic control, suggesting that non-ideal long term glycaemic control leads to neuropathy in a subset of predisposed patients. VPT was correlated in 123 diabetic patients with definitive criteria for neuropathy and a range of quantitative sensory and autonomic tests. 62/63 patients with abnormal VPT fulfilled neuropathy criteria; of patients with normal VPT who fulfilled neuropathy criteria, all had at least one abnormal thermal threshold test result. We conclude that a combination of log-transformed VPT values (VPTscore > 10.1) and thermal thresholds can identify diabetic patients at risk of developing peripheral neuropathy and select patients likely to benefit from prophylaxis in clinical trials.
Copyright 2001 Harcourt Publishers Ltd.