The diabetes control and complications trial/epidemiology of diabetes interventions and complications study at 30 years: summary and future directions.

OBJECTIVE The Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications (DCCT/EDIC) study continues to address knowledge gaps in our understanding of type 1 diabetes and the effects of intensive therapy on its long-term complications. RESEARCH DESIGN AND METHODS During the DCCT (1982-1993), a controlled clinical trial of 1,441 subjects with type 1 diabetes, and the EDIC (1994-present), an observational study of the DCCT cohort, core data collection has included medical history questionnaires, surveillance health exams, and frequent laboratory and other evaluations for microvascular and macrovascular disease. Numerous collaborations have expanded the outcome data with more detailed investigations of cardiovascular disease, cognitive function, neuropathy, genetics, and potential biological pathways involved in the development of complications. RESULTS The longitudinal follow-up of the DCCT/EDIC cohort provides the opportunity to continue monitoring the durability of intensive treatment as well as to address lingering questions in type 1 diabetes research. Future planned analyses will address the onset and progression of microvascular triopathy, evidence-based screening for retinopathy and nephropathy, effects of glycemic variability and nonglycemic risk factors on outcomes, long-term impact of intensive therapy on cognitive decline, and health economics. Three new proposed investigations include an examination of residual C-peptide secretion and its impact, prevalence of hearing impairment, and evaluation of gastrointestinal dysfunction. CONCLUSIONS With the comprehensive data collection and the remarkable participant retention over 30 years, the DCCT/EDIC continues as an irreplaceable resource for understanding type 1 diabetes and its long-term complications.