Relationship of hemoglobin A1C and mortality in heart failure patients with diabetes

J Am Coll Cardiol. 2009 Jul 28;54(5):422-8. doi: 10.1016/j.jacc.2009.04.049.

Abstract

Objectives: This study was designed to examine the relationship between glycosylated hemoglobin (HbA1C) and adverse outcomes in diabetic patients with established heart failure (HF).

Background: Despite the common coexistence of diabetes and HF, previous studies examining the association between HbA1C and outcomes in this population have been limited and have reported discrepant results.

Methods: We assessed the association between increasing quintiles (Q1 to Q5) of HbA1C and risk of death or risk of HF hospitalization by conducting a retrospective study in a national cohort of 5,815 veterans with HF and diabetes treated in ambulatory clinics at Veterans Affairs medical centers.

Results: At 2 years of follow-up, death occurred in 25% of patients in Q1 (HbA1C < or =6.4%), 23% in Q2 (6.4% < HbA1c < or =7.1%), 17.7% in Q3 (7.1% < HbA1c < or =7.8%), 22.5% in Q4 (7.8% < HbA1c < or =9.0%), and 23.2% in Q5 (HbA1c >9.0%). After adjustment for potential confounders, the middle quintile (Q3) had reduced mortality when compared with the lowest quintile (risk-adjusted hazard ratio: 0.73, 95% confidence interval: 0.61 to 0.88, p = 0.001). Hospitalization rates for HF at 2 years increased with increasing quintiles of HbA1C (Q1: 13.3%, Q2: 13.1%, Q3: 15.5%, Q4: 16.4%, and Q5: 18.2%), but this association was not statistically significant when adjusted for potential confounders.

Conclusions: The association between mortality and HbA1C in diabetic patients with HF appears U-shaped, with the lowest risk of death in those patients with modest glucose control (7.1% < HbA1C < or =7.8%). Future prospective studies are necessary to define optimal treatment goals in these patients.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Aged
  • Aged, 80 and over
  • Diabetes Mellitus, Type 2 / blood*
  • Diabetes Mellitus, Type 2 / complications
  • Diabetes Mellitus, Type 2 / mortality*
  • Female
  • Glycated Hemoglobin A / analysis*
  • Heart Failure / blood*
  • Heart Failure / complications
  • Heart Failure / mortality*
  • Humans
  • Male
  • Middle Aged
  • Retrospective Studies
  • Risk Factors

Substances

  • Glycated Hemoglobin A