Hyperglycemia and Death in Cystic Fibrosis–Related Diabetes

OBJECTIVE: Diabetes is common in cystic fibrosis and increases the risk of death, yet the role of hyperglycemia remains unproven. An association between glycemia and mortality would provide compelling evidence to support glucose lowering in cystic fibrosis–related diabetes (CFRD). RESEARCH DESIGN AND METHODS: Using the U.K. Cystic Fibrosis Registry, we analyzed longitudinal data from 2006 to 2009 in 520 individuals with diabetes. We tested the association between HbA(1c) and mortality. RESULTS: During a median follow-up of 2 years, 36 patients died. The median value of HbA(1c) was higher in those who died (7.3%) than in those who did not (6.7%). An HbA(1c) value of ≥6.5% was associated with a threefold increased risk of death (hazard ratio 3.2 [95% CI 1.4–7.3]; P = 0.005) independent of potential confounders. CONCLUSIONS: Hyperglycemia trebles the risk of death in patients with CFRD. These findings provide epidemiologic support for continued efforts to improve glycemic control.