A1c Below Prediabetes Cutoff Linked to Subclinical Atherosclerosis

Richard Mark Kirkner

June 15, 2021

Hemoglobin A1c above 5% but below the prediabetes cutoff of 5.5% is an additional potential biomarker of subclinical atherosclerosis in people with low cardiovascular disease risk, according to an analysis of data on almost 4,000 middle-aged individuals.

"If one looks at the incidence of generalized subclinical atherosclerosis, we are not talking small numbers," senior study author Valentin Fuster, MD, PhD, said in an interview. "We are talking about between 45% and 82% of this middle-age population that already has atherosclerotic disease subclinically.

"Actually," he added, "the disease was extensive in 5%-30% of these individuals of middle age."

The study included 3,973 participants from the Progression of Early Subclinical Atherosclerosis study who did not have diabetes. A1c showed an association with the prevalence and multiterritorial extent of subclinical atherosclerosis as measured by two-dimensional ultrasound and coronary artery calcium score (CACS; P < .001). For example, those with A1c above 6.1% (133 participants) had a 33.1% rate of generalized subclinical atherosclerosis, compared with 4.9% for those with A1c below 4.8% (243), the lowest-score group in the study.

Patients in the subprediabetes band, between 5.0% and 5.5%, had significantly higher rates of generalized subclinical atherosclerosis than did the lowest-score group: 8% in the 4.9%-5.0% group (375 participants); 9.9% in the 5.1%-5.2% range (687); 10.3% in the 5.3%-5.4% group (928); and 11.5% in the 5.5%-5.6% group (842).

Those in the 5.1%-5.2% and 5/3%-5.4% A1c groups had a 27% greater chance of having subclinical atherosclerosis, while those in the 5.5%-5.6% group had a 36% greater risk, according to an odds ratio analysis adjusted for established cardiovascular risk factors. The risks were even higher for patients with prediabetes, the researchers reported in the Journal of the American College of Cardiology.

A Call for Earlier Intervention

Notably, the study found that fasting plasma glucose testing did not yield a similar association between A1c and atherosclerosis.

"The message is that we all talk about people when they are close to the development of cardiovascular events, and here we are talking about people who we should pay attention to much earlier," said Fuster, physician-in-chief at Icahn School of Medicine at Mount Sinai in New York and director of the National Center for Cardiovascular Investigation in Madrid, where the observational study originated said. "People should be sensitized to HbA1c much more than they would've been in the past, and I think this study actually validates that."

Christie Ballantyne, MD, noted in an interview that these findings support the utility of A1c for predicting CVD risk.

"I think more and more we should be ordering a HbA1c" during routine physical exams, Ballantyne said. "You don't have to be obese to get it; there are lots of people, maybe they're slightly overweight. It's a reasonable test to be getting when you get to middle age and older to get an idea for assessing for both developing diabetes and also the presence of atherosclerosis and the risk for having cardiovascular events."

Ballantyne, chief of cardiology at Baylor College of Medicine and director of cardiovascular disease prevention at Methodist DeBakey Heart Center in Houston, coauthored an editorial comment on the study.

Clinicians typically start to manage CVD and diabetes risk "late in the process," Ballantyne said. This study suggested that earlier use of antidiabetes therapies, namely peptide-1 agonists and semisynthetic glucagon-like peptide-2 inhibitors, may be warranted in patients with intermediate risk of CVD.

"It's just more data for the rationale that, perhaps we could end up doing trials to show we can take high-risk people and prevent them from getting both heart disease and diabetes," Ballantyne added. "Could we start a little earlier with better precision?"

These finding don't yet call for a change in how cardiologists and endocrinologists manage patients on the cusp of prediabetes, said Paul S. Jellinger, MD, of Hollywood, Fla., and a professor at the University of Miami. "The endpoint of subclinical atherosclerosis does not necessarily translate into the harder endpoint of CVD events, although there is certainly reason to believe it does," he said in an interview, noting that he's often used CACS to stratify atherosclerotic CVD risk in patients.

"I will now consider extending that assessment to patients with lower A1c levels," he said.

If future studies validate this finding, he said, "serious consideration will have to be made for treating the very large numbers of patients with A1c levels in the prediabetic range and below with antidiabetic agents that have ASCVD prevention properties while lowering A1c. We have those agents today."

The Progression of Early Subclinical Atherosclerosis study received funding from the National Center for Cardiovascular Investigation in Madrid, Santander Bank, and the Carlos III Health Institute in Madrid. Fuster had no disclosures. Ballantyne disclosed receiving research funding through his institution from Abbott Diagnostic, Akcea, Amgen, Esperion, Ionis, Novartis, Regeneron, and Roche Diagnostic; and has served as a consultant for Abbott Diagnostics, Althera, Amarin, Amgen, Arrowhead, AstraZeneca, Corvidia, Denka Seiken, Esperion, Genentech, Gilead, Matinas BioPharma, New Amsterdam, Novartis, Novo Nordisk, Pfizer, Regeneron, Roche Diagnostic and Sanofi-Synthélabo.

Jellinger had no disclosures.

This article originally appeared on MDedge.com, part of the Medscape Professional Network.


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