Natural progression of diabetic peripheral neuropathy in the Zenarestat study population.

OBJECTIVE The aim of this study was to report the baseline and natural progression of diabetic peripheral neuropathy over 12 months in a large mild-to-moderate neuropathy population. RESEARCH DESIGN AND METHODS Patients from a multicentered trial of zenarestat, an aldose reductase inhibitor, had serial measures of neurologic function, including nerve conduction studies (NCSs), quantitative sensory testing (QST), and clinical neuropathy rating scores at baseline and at 12 months. Baseline population descriptors and changes in neurologic function in placebo-treated patients were analyzed. RESULTS Sural sensory velocity (P = 0.0008 [95% CI -1.04 to -0.27]), median sensory amplitude (P = 0.0021 [-1.3 to -0.29]), median distal motor latency (P = 0.002 [0.09-0.28]), cool thermal QST (P = 0.0005 [0.27-0.94]), and Michigan Neuropathy Screening Instrument results (P = 0.0087 [0.04-0.30]) declined significantly from baseline in the placebo population. NCS changes from baseline were independent of baseline HbA1c stratification. CONCLUSIONS The neurologic decline over 12 months is evident when measured by NCS and cool thermal QST. Other measures (vibration QST, neuropathy rating scores, monofilament examination) are insensitive to changes over 12 months in a mild-to-moderate affected population of this size.