« Back

A1C level predicts risk of CVD, all-cause death better than FPG among adults without diabetes, data suggest

Wednesday, March 10 2010 | Comments

---

What's This? Among adults without diabetes, elevated levels of hemoglobin A1C and fasting plasma glucose (FPG) are similarly associated with diabetes risk, but A1C seems to be a better predictor of cardiovascular disease (CVD) and all-cause death, according to an analysis of data from the ARIC study.

Researchers evaluated data for 11,092 adults with no history of diabetes or CVD who provided an A1C measurement during the 1990-92 ARIC follow-up assessment. In the current analysis, they evaluated the risk of diabetes, coronary heart disease (CHD), ischemic stroke, and all-cause death with A1C categories (<5%, 5% to <5.5%, 5.5% to <6%, 6% to <6.5%, and >=6.5%) and FPG categories (<100 mg/dL, 100 mg/dL to <126 mg/dl, and >=126 mg/dL).

In an analysis adjusted for covariates (age, sex, race, lipids, body mass index, waist-to-hip ratio, hypertension, family history of diabetes, education, alcohol use, physical activity, and smoking), baseline A1C level was significantly associated with subsequent development of diabetes, CHD, stroke, and death.

Relative to the individuals with an A1C level ranging from 5% to <5.5%, the risk of diabetes decreased significantly in the lower A1C category and increased significantly in the higher A1C categories, from a 48% reduction in risk in those with an A1C level of <5% to a greater than 16-fold increase in risk in those with an A1C level >=6.5%.

In addition, relative to the reference A1C category of 5% to <5.5%, the risk of both CHD and stroke increased significantly in the higher A1C categories; those in the highest A1C category were nearly twice as likely to develop CHD and were more than 3 times as likely to experience a stroke.

There was a J-shaped association between A1C level and all-cause death. Relative to the reference A1C category of 5% to <5.5%, the risk of death increased significantly in the lower and higher A1C categories.

A1C level remained significantly associated with diabetes, CHD, stroke, and death after additional adjustment for baseline FPG.

In analyses adjusted for covariates, relative to FPG levels <100 mg/dL, the higher FPG levels were associated with subsequent diabetes, and these associations remained significant after additional adjustment for baseline A1C level. However, only the highest FPG category (>=126 mg/dL) was significantly associated with an increased risk of CHD, stroke, and all-cause death in analyses adjusted for covariates, and these associations were no longer significant after additional adjustment for baseline A1C level.

The authors noted that measures of CHD risk discrimination improved significantly when A1C level was added to the models that included FPG, "suggesting that glycated hemoglobin may be superior to fasting glucose for characterizing long-term risk." (Selvin E, et al. N Engl J Med 2010;362:800-811.)

Print  |  E-mail