Glycosylated hemoglobin and coronary artery disease in patients without diabetes mellitus

Background Abnormal glucose metabolism is a major determinant of coronary artery disease (CAD) and mortality in developed countries. Glycosylated hemoglobin (HbA1c) is a more stable, accurate parameter of glucose homeostasis than fasting glycemia, thus providing prognostic information in diabetics. However, its role and relationship with CAD remains unclear in non-diabetics. Purpose To evaluate the relationship between HbA1c and CAD in a consecutive cohort of patients without diabetes mellitus. Methods Non-diabetic patients undergoing coronary angiography between April 2007 and October 2012 were included. Additionally carotid intima-media thickness (C-IMT) was evaluated during hospitalization in a consecutive cohort of patients. Results 1,703 consecutive patients were included and divided according to HbA1c tertiles (<5.5%, 5.5%-5.79%, ≥5.8%). HbA1c was associated with aging (p<0.001); hypercholesterolemia (p=0.01); renal failure (p=0.006); hypertension (p=0.002); previous myocardial infarction (p=0.004); previous percutaneous coronary intervention (p=0.01); indication to angiography (p=0.01); use of angiotensin receptor blockers (p=0.01); beta-blockers (p=0.03); nitrates (p=0.02); statins (p=0.008); calcium antagonists (p=0.01); diuretics (p<0.001); acetylsalicylic acid (p<0.001); baseline glycemia (p<0.001); triglycerides (p=0.02); and uric acid (p=0.04). HbA1c, but not fasting glycemia, was significantly associated with the prevalence of CAD (adjusted OR=1.51, 95% CI=1.15, 1.97, p=0.002), with 5.8% identified by the receiver operating characteristic (ROC) curve as the best cut-off value for CAD prediction. HbA1c was significantly associated with C-IMT and carotid plaques prevalence. Conclusions Among non-diabetic patients, higher HbA1c even within the normal range is significantly associated with the risk of CAD. Future large studies are needed to evaluate whether more aggressive cardiovascular prevention can reduce the risk of CAD among patients with HbA1c≥5.8%.