Relationship of hemoglobin A1C and mortality in heart failure patients with diabetes.
OBJECTIVE
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.
Aguilar
David
D
Winters Center for Heart Failure Research and Section of Cardiology, Department of Medicine, Baylor College of Medicine, 1709 Dryden Street-BCM 620, Suite 500, Box 13, Houston, Texas 77030, USA. daguilar@bcm.edu
Bozkurt
Biykem
B
Ramasubbu
Kumudha
K
Deswal
Anita
A
D000368:Aged; D000369:Aged, 80 and over; D003924:Diabetes Mellitus, Type 2 / Q000097:blood* / Q000150:complications / Q000401:mortality*; D005260:Female; D006442:Glycated Hemoglobin / Q000032:analysis*; D006333:Heart Failure / Q000097:blood* / Q000150:complications / Q000401:mortality*; D006801:Humans; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D012307:Risk Factors
D006442:Glycated Hemoglobin