ORLANDO — Elevated levels of hemoglobin A1c were linked with a significantly increased risk of heart failure in a review of more than 11,000 American adults without diabetes.
“Hemoglobin A1c may be a better biomarker to evaluate the risk of heart failure compared with fasting glucose in nondiabetic populations,” Dr. Kunihiro Matsushita said at the annual scientific sessions of the American Heart Association.
Prior study results linked higher hemoglobin A1c levels with heart failure in patients with diabetes, but no previous study looked at this relationship in people without diabetes, said Dr. Matsushita, an epidemiologist in the Johns Hopkins Bloomberg School of Public Health, Baltimore.
Diabetes is an established risk factor for heart failure.
The new study used some of the more than 15,000 Americans aged 45-64 years who enrolled in the Atherosclerosis Risk in Communities study in four U.S. locations in 1987.
The analysis focused on the 11,196 study participants who underwent an examination in 1990-1992 that included HbA1c measurement and did not have diabetes or heart failure at that time. Their average age was 56, and 56% were women.
When analyzed by HbA1c level at their examination in 1990-1992, 9% had a level of less than 5%, 47% had a level of 5.0%-5.4%, 35% had a level of 5.5%-5.9%, 8% had a level of 6.0%-6.4%, and 1% had a level of 6.5% or higher.
During a median follow-up of 14 years, 871 cases of incident heart failure developed. The data showed a continuous association between baseline level of HbA1c and subsequent heart failure.
In a model that adjusted for age, gender, and race, the rate of heart failure cases per 1,000 person-years of follow-up rose from 5 among those with a HbA1c level of 5% to 6 in those with a level of 5.5%, 9 in those with a level of 6%, and 16 in people with a 6.5% level.
Dr. Matsushita and his associates ran additional models that adjusted for many other baseline variables, including smoking, alcohol intake, body mass index, blood pressure, cholesterol levels, kidney function, and fasting glucose.
In the fully adjusted model, people with a baseline HbA1c of 6.0%-6.4% had a 41% increased risk of heart failure during follow-up, compared with the reference group that started with a HbA1c level of 5.0%-5.4%. People who began with a level of 6.5% or greater had more than a twofold risk compared with the reference group. Both differences were significant.
The analysis also showed that higher levels of HbA1c were more predictive than were high baseline levels of fasting blood glucose.
In a similar, fully adjusted model that controlled for baseline HbA1c, people whose baseline fasting blood glucose was either 100-109 mg/dL or 110-125 mg/dL did not have a significantly higher risk of developing heart failure than did the reference group with a baseline fasting glucose level of 90-99 mg/dL.
Additional analysis by the Johns Hopkins researchers showed that the interaction between HbA1c and heart failure did not depend on coronary heart disease to mediate the effect.
When the analysis eliminated the 482 cases of coronary heart disease that occurred during follow-up before those people developed heart failure, the significant link between baseline HbA1c and incident heart failure remained, Dr. Matsushita said.
Dr. Matsushita reported that he and his associates had no financial relationships to disclose.
HbA1c may be a better biomarker of heart failure risk than fasting glucose in nondiabetic populations.
Source DR. MATSUSHITA