ADA 2010: Glycated hemoglobin levels correlate strongly to future diabetes, cardiovascular risk

An ancillary study to the ARIC (Atherosclerosis Risk in Communities) study supports the most recent (2010) ADA risk categories of glycated hemoglobin in identifying future risk of developing diabetes and macrovascular and microvascular disease. The data were presented by Elizabeth Selvin, PhD.

The ADA now recommends the use of glycated hemoglobin for the diagnosis of diabetes and identification of persons at increased risk for diabetes. The ADA defines an HbA1c of 5.7% to less than 6.5% as "high risk" for the future development of diabetes.

In this analysis, 11,092 participants from ARIC, a large community-based epidemiologic study, without cardiovascular disease or diabetes at baseline had glycated hemoglobin measured from stored whole blood samples obtained between 1990 and 1992. Participants were followed for 15 years.

"In individuals with an A_1c of 5.7% to less than 6.5%, which is the group identified as high risk for the development of diabetes and other complications, we see a very high risk of the subsequent development of diabetes. We can also see that individuals in that range are at risk for kidney disease, CHD [coronary heart disease], and stroke," said Selvin, assistant professor of epidemiology and medicine at Johns Hopkins in Baltimore.

Compared with the reference population with a glycated hemoglobin level of 5% to less than 5.7%, those in the high-risk category of 5.7% to less than 6.5% had more than triple the risk of diagnosed diabetes, a 60% increase in the risk of CHD, a 56% increase in the risk of stroke, a 62% increased risk of end-stage renal disease, and a 42% increase in all-cause mortality, all adjusted for age, sex, race, and other potential confounders.

These risks were even greater in the cohort with glycated hemoglobin levels of 6.5% or greater at baseline.

"The vast majority of individuals with glycated hemoglobin values greater than 6.5% will subsequently be diagnosed with diabetes during follow-up, and they're at very high risk of kidney disease and have almost 4 times the risk of developing end-stage renal disease compared to those people in the normal range, and a 2-fold increased risk of developing CHD or stroke or dying during follow-up," she said.

More than 20% of the group with glycated hemoglobin values of 5.7% to less than 6.5% and almost 80% of those with values of 6.5% or greater developed diabetes within 10 years.