Intensive Diabetes Treatment and Cardiovascular Outcomes in Type 1 Diabetes: The DCCT/EDIC Study 30-Year Follow-up

Abstract

Objective: Early initiation of intensive diabetes therapy aimed at achieving near-normal glycemia reduces the early development of vascular complications in type 1 diabetes. We now assess whether intensive therapy compared with conventional therapy during the Diabetes Control and Complications Trial (DCCT) affected the incidence of cardiovascular disease over 30 years of follow-up.

Research design and methods: The DCCT randomly assigned 1,441 patients with type 1 diabetes to intensive versus conventional therapy for a mean of 6.5 years, after which 93% were subsequently monitored during the observational Epidemiology of Diabetes Interventions and Complications (EDIC) study. Cardiovascular disease (nonfatal myocardial infarction and stroke, cardiovascular death, confirmed angina, congestive heart failure, and coronary artery revascularization) was adjudicated using standardized measures.

Results: During 30 years of follow-up in DCCT and EDIC, 149 cardiovascular disease events occurred in 82 former intensive treatment group subjects versus 217 events in 102 former conventional treatment group subjects. Intensive therapy reduced the incidence of any cardiovascular disease by 30% (95% CI 7, 48; P = 0.016), and the incidence of major cardiovascular events (nonfatal myocardial infarction, stroke, or cardiovascular death) by 32% (95% CI -3, 56; P = 0.07). The lower HbA1c levels during the DCCT/EDIC statistically account for all of the observed treatment effect on cardiovascular disease risk. Increased albuminuria was also independently associated with cardiovascular disease risk.

Conclusions: Intensive diabetes therapy during the DCCT (6.5 years) has long-term beneficial effects on the incidence of cardiovascular disease in type 1 diabetes that persist for up to 30 years.

Trial registration: ClinicalTrials.gov NCT00360815 NCT00360893.

Figure 1

Cumulative incidence of cardiovascular outcomes in the conventional treatment and intensive treatment groups during up to 30 years of DCCT/EDIC treatment and follow-up. A: The first of any of the predefined CVD outcomes. The risk reduction with intensive therapy was 30% (95% CI 7, 48; P = 0.016). B: The first occurrence of MACE. The risk reduction with intensive therapy was 32% (95% CI −3, 56; P = 0.07).

Figure 2

Underlying HR function representing the risk of a new event among those remaining at risk at every point in time. Note that the number of subjects at risk declines beyond year 24 owing to staggered entry of subjects during 1983–1989. A: Any CVD. B: MACE.