Neuropathy Among the Diabetes Control and Complications Trial Cohort 8 Years After Trial Completion

Neuropathy Among the Diabetes Control and Complications Trial Cohort 8 Years After Trial Completion Catherine L. Martin , MS , James Albers , MD, PHD , William H. Herman , MD, MPH , Patricia Cleary , MS , Barbara Waberski , MS , Douglas A. Greene , MD , Martin J. Stevens , MD and Eva L. Feldman , MD, PHD Diabetes Control and Complications Trial (DCCT)/Epidemiology of Diabetes Intervention and Complications (EDIC) Research Group Address correspondence and reprint requests to the DCCT/EDIC Research Group, Box DCCT/EDIC Bethesda, MD 20892. E-mail: cleary{at}biostat.bsc.gwu.edu Abstract OBJECTIVE —To evaluate the impact of prior intensive diabetes therapy on neuropathy among former Diabetes Control and Complications Trial (DCCT) participants. RESEARCH DESIGN AND METHODS —At the conclusion of the DCCT, subjects in the intensive group were encouraged to maintain intensive therapy, and subjects in the conventional group were encouraged to begin intensive therapy. Thereafter, we annually assessed neuropathy as part of the Epidemiology of Diabetes Intervention and Complications (EDIC) study. Neuropathy was defined using the Michigan Neuropathy Screening Instrument (MNSI). We recorded potential adverse consequences of neuropathy. RESULTS —At the first EDIC examination, 1,257 subjects participated in the neuropathy assessment. Consistent with DCCT results, the former intensive group showed a lower prevalence of neuropathy than the conventional group based on positive questionnaire (1.8 vs. 4.7%; P = 0.003) or examination (17.8 vs. 28.0%; P < 0.0001) results. Despite similar levels of glycemic control, symptoms and signs of neuropathy remained less prevalent among the former intensive group compared with the conventional group. At the beginning of the EDIC study, prior intensive therapy reduced the odds of having symptoms and signs of neuropathy using MNSI criteria by 64% ( P = 0.0044) and 45% ( P < 0.0001), respectively, with similar odds reductions observed for both neuropathic symptoms (51%, P < 0.0001) and neuropathic signs (43%, P < 0.0001) across 8 years of EDIC follow-up. CONCLUSIONS —The benefits of 6.5 years of intensive therapy on neuropathy status extended for at least 8 years beyond the end of the DCCT, similar to the findings described for diabetic retinopathy and nephropathy. DCCT, Diabetes Control and Complications Trial EDIC, Epidemiology of Diabetes Intervention and Complications MNSI, Michigan Neuropathy Screening Instrument Footnotes J.A. is a paid consultant for Eli Lilly. A list of the people and institutions participating in the DCCT/EDIC Research Group appears in the appendix . A table elsewhere in this issue shows conventional and Système International (SI) units and conversion factors for many substances. Accepted November 2, 2005. Received August 17, 2005. DIABETES CARE