Among patients who don’t have diabetes, high-normal hemoglobin A1C levels (at or above 5.8%) are strongly correlated with the risk of coronary artery disease, according to a report published online April 21 in the American Journal of Preventive Medicine.
In what they described as the first large-scale study to assess the relationships among A1C, CAD, and carotid intima-medial thickness, researchers enrolled 1,703 consecutive patients undergoing either elective or urgent coronary angiography at a single medical center during a 5-year period. These nondiabetic patients were divided into tertiles according to their A1C levels: low (less than 5.5%), intermediate (5.5%-5.79%), or high (5.8% or higher), reported Dr. Monica Verdoia of the cardiology department, Maggiore della Carita Hospital, Novara (Italy), and her associates.
A1C was significantly associated in a dose-dependent fashion with the prevalence of CAD on angiography (odds ratio, 1.33). CAD prevalence was 66.9% in patients who had low-normal A1C, 73.7% in those with intermediate A1C, and 78.6% in those with high-normal A1C. This association remained robust after the data were adjusted to account for many confounding factors, including patient age and sex; the presence or absence of hypertension, hypercholesterolemia, renal failure, and previous myocardial infarction; and the use or nonuse of medications including angiotensin receptor blockers, beta-blockers, nitrates, statins, or diuretics, the investigators said (Am. J. Prev. Med. 2014 April 21 [doi: 10.1016/j.amepre.2014.02.002]).
This strong association between high-normal A1C and CAD prevalence persisted across every high-risk subgroup that was assessed. A1C also was independently and strongly associated with carotid intima-medial thickness and the prevalence of carotid plaques on ultrasonography.
The best cutoff value for predicting the presence of significant CAD was determined to be 5.8%. Even though this level is within the normal range, it "should be regarded as a risk factor for atherosclerosis," Dr. Verdoia and her associates said.
Future research is needed to confirm these findings and to assess whether more aggressive preventive strategies, such as lifestyle changes, the use of statins, or antiplatelet therapies, might reduce the development and progression of atherosclerosis in such patients, they added.
Dr. Verdoia and her associates reported no financial conflicts of interest.