Effect Of Prior Intensive Insulin Treatment During The Diabetes Control And Complications Trial (DCCT) On Peripheral Neuropathy In Type 1 Diabetes During The Epidemiology Of Diabetes Interventions, And Complications (EDIC) Study

  1. for the DCCT/EDIC Research Group (jwalbers{at}
  1. 1 Department of Neurology, University of Michigan Medical School, Ann Arbor, MI
  2. 2 Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, MI
  3. 3 George Washington University, The Biostatistics Center, Rockville, MD


Objective: To evaluate the impact of former intensive- versus conventional insulin treatment on neuropathy in DCCT intensive and conventional treatment subjects with type 1 diabetes 13-14 years after DCCT closeout, during which time the two groups had achieved similar hemoglobin A1c (HbA1c) levels.

Research Design and Methods: Clinical and nerve conduction studies (NCSs) performed during DCCT were repeated during EDIC by examiners masked to treatment status on 603 former intensive- and 583 former conventional-treatment subjects. Clinical neuropathy was defined by symptoms, sensory signs, or reflex changes consistent with distal polyneuropathy and confirmed with NCS abnormalities involving ≥ 2 nerves among the median, peroneal, and sural nerves.

Results: The prevalence of neuropathy increased 13-14 years after DCCT closeout from 9% to 25% in former intensive- and from 17% to 35% in former conventional treatment groups, but the difference between groups remained significant (P<0.001) and the incidence of neuropathy remained lower among former intensive- (22%) than former conventional treatment subjects (28%) (P=0.0125). Analytic models of incident neuropathy that adjusted for differences in NCS results at DCCT closeout showed no significant risk reduction associated with former intensive treatment during follow-up (OR=1.17; CI=0.84-1.63). However, a significant persistent treatment group effect was observed for several NCS measures. Longitudinal analyses of overall glycemic control showed a significant association between mean HbA1c and measures of incident and prevalent neuropathy.

Conclusions: The benefits of former intensive insulin treatment persisted for 13-14 years after DCCT closeout and provide evidence of a durable effect of prior intensive treatment on neuropathy.


    • Received October 20, 2009.
    • Accepted January 27, 2010.

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  1. Diabetes Care
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