PROGRESSION RATES OF DIABETIC NEUROPATHY IN PLACEBO PATIENTS IN AN 18-MONTH CLINICAL-TRIAL

Recent clinical drug trials designed to test the effect on established mild diabetic neuropathy have in general been disappointing. These fi ndings may in part be due to a failure of tested drugs to reverse neur opathy (they may merely halt its progression) and to insufficient dura tions of the trials. To aid the design of future studies, we examined the progression rates of quantitative sensory tests, autonomic functio ns, and sensory and motor nerve electrophysiology in 182 patients desi gned to placebo treatment in an 18-month multicenter ARI-trial. Clinic ally meaningful deteriorations were demonstrated in the vibratory perc eption threshold in the toe and the Valsalva ratio. The greatest deter ioration rate in electrophysiologic measures was found in peroneal F-w ave latency and in sensory nerve conduction velocities in the upper li mb, but none of these reached the threshold of clinically meaningful c hange. Assuming that drug efficacy will be based on the deterioration rates in placebo patients alone, the present data suggest a minimum of 250 patients treated for at least 2 years to achieve convincing effic acy. (C) 1998 Elsevier Science Inc.