Elevated glycated haemoglobin is a strong predictor of mortality in patients with left ventricular systolic dysfunction who are not receiving treatment for diabetes mellitus

Background:

Glycated haemoglobin (HbA1c) is an indicator of average blood glucose concentrations over the preceding 3 months, is simpler to perform than either a fasting glucose or glucose tolerance test and is associated with a worse prognosis in some clinical settings. However, its relationship to survival in patients with suspected heart failure has not been studied.

Methods:

Patients referred to a community-based heart failure clinic with suspected heart failure had a comprehensive assessment including the measurement of HbA1c. For this analysis, patients with DM or who started diabetic medication in the subsequent 12 months, which might influence HbA1c, were excluded.

Findings:

Of 970 non-diabetic patients referred between 2001 and 2004, the median age was 72 years (range 25 to 96 years), 56% were men, 45% had left ventricular ejection fraction (LVEF) ⩽45%, and 50% had an HbA1c >6% (upper reference limit). Among patients with LVEF ⩽45%, there was an abrupt increase in mortality in those with an HbA1c >6.7% (n = 68) compared with those with HbA1c ⩽6.7% (n = 368) (hazard ratio (HR): 2.4, p<0.001), and this persisted after adjustment for age and comorbidity (HR 1.9, p = 0.008); respective 1-year mortalities were 26.5% and 9.4%. This increase in mortality was not seen in those with LVEF >45% (HR 1.44, p = 0.36 after adjustment).

Interpretation:

The abrupt increase in mortality with HbA1c may make it a useful risk stratification tool in non-diabetic patients with LVEF ⩽45% which could help improve clinical management.