Association of Glycemic Control With Reduced Risk for Large-Vessel Disease After More Than 50 Years of Type 1 Diabetes.

Context: Previously we demonstrated, in individuals who have had type 1 diabetes (T1D) for 50 or more years (Medalists), that glycemic control was unrelated to diabetic complications, with the exception of cardiovascular disease (CVD), contrary to what has been documented in registry-based studies.

Objective: The purpose of this study is to validate these initial findings and identify contributors to mortality on an individual basis in a large cohort.

Design: Cross-sectional and longitudinal study.

Setting: Joslin Diabetes Center (JDC), Boston, Massachusetts.

Patients: 50-year Medalists presenting to JDC for study participation.

Interventions: None.

Main Outcomes Measures: Microvascular and macrovascular complications of diabetes and mortality.

Results: Glycemic control was not significantly associated with small-vessel complications in Medalists but was associated with CVD in the overall cohort, yet with varying effect by tertile of cohort duration. CVD was the largest contributor to mortality, whereas hemoglobin A1c was not an independent predictor of mortality either overall or substantially by diagnosis interval. Additionally, exercise mitigated mortality risk imparted by CVD.

Conclusions: Few large populations with long duration of (T1D) have been available to examine the effects of long-term exposure to hyperglycemia. These data indicate that an association of glycemic control, complications, and mortality may change in an older population with T1D. These results suggest that careful control is still warranted in older populations with T1D.