Association between 7 years of intensive treatment of type 1 diabetes and long-term mortality.

Importance Whether mortality in type 1 diabetes mellitus is affected following intensive glycemic therapy has not been established. Objective To determine whether mortality differed between the original intensive and conventional treatment groups in the long-term follow-up of the Diabetes Control and Complications Trial (DCCT) cohort. Design, Setting, and Participants After the DCCT (1983-1993) ended, participants were followed up in a multisite (27 US and Canadian academic clinical centers) observational study (Epidemiology of Diabetes Control and Complications [EDIC]) until December 31, 2012. Participants were 1441 healthy volunteers with diabetes mellitus who, at baseline, were 13 to 39 years of age with 1 to 15 years of diabetes duration and no or early microvascular complications, and without hypertension, preexisting cardiovascular disease, or other potentially life-threatening disease. Interventions and Exposures During the clinical trial, participants were randomly assigned to receive intensive therapy (n = 711) aimed at achieving glycemia as close to the nondiabetic range as safely possible, or conventional therapy (n = 730) with the goal of avoiding symptomatic hypoglycemia and hyperglycemia. At the end of the DCCT, after a mean of 6.5 years, intensive therapy was taught and recommended to all participants and diabetes care was returned to personal physicians. Main Outcomes and Measures Total and cause-specific mortality was assessed through annual contact with family and friends and through records over 27 years’ mean follow-up. Results Vital status was ascertained for 1429 (99.2%) participants. There were 107 deaths, 64 in the conventional and 43 in the intensive group. The absolute risk difference was −109 per 100 000 patient-years (95% CI, −218 to −1), with lower all-cause mortality risk in the intensive therapy group (hazard ratio [HR] = 0.67 [95% CI, 0.46-0.99]; P  = .045). Primary causes of death were cardiovascular disease (24 deaths; 22.4%), cancer (21 deaths; 19.6%), acute diabetes complications (19 deaths; 17.8%), and accidents or suicide (18 deaths; 16.8%). Higher levels of glycated hemoglobin (HbA 1c ) were associated with all-cause mortality (HR = 1.56 [95% CI, 1.35-1.81 per 10% relative increase in HbA 1c ]; P P Conclusions and Relevance After a mean of 27 years’ follow-up of patients with type 1 diabetes, 6.5 years of initial intensive diabetes therapy was associated with a modestly lower all-cause mortality rate when compared with conventional therapy. Trial Registration clinicaltrials.gov Identifiers:NCT00360815andNCT00360893