Hgba1c as an independent risk factor for diabetes, CVD and death?

The Buzz: Glycated hemoglobin may be a useful marker for predicting development of diabetes, cardiovascular risk and death
Citation:  "Glycated Hemoglobin, Diabetes and Cardiovascular Risk in Nondiabetic Adults." NEJM 362;9 March 4, 2010 800-11

Summary: This multi-center study followed 11,092 middle-aged adults without diabetes over a 15 year period in order to study the use of glycated hemoglobin to predict risk of diabetes, coronary heart disease and death. Using thawed blood samples taken during subjects' earlier visits, researchers calculated adjusted hazard ratios for those with HgbA1c values below 7.0%, ie nondiabetics. HgbA1c values were as good as fasting glucose values for predicting risk of developing diabetes, and appeared to be better than fasting glucose as a predictor of long-term macrovascular event risk. For A1c values of <5.0%, 5.0%-<5.5%, 5.5%-<6.0%, 6.0%-<6.5% and >6.5%, the multivariable-adjusted hazard ratios were 0.52, 1.00, 1.86, 4.48 and 16.47, respectively for developing diabetes, and 0.96, 1.00, 1.23, 1.78, and 1.95, respectively for coronary heart disease (all values significant). Similar findings were reported for stroke and death from any cause.The authors concluded that not only does this study further support the use of glycated hemoglobin values to predict diabetes risk, but that values over 6.0% may be an independent risk factor for cardiovascular disease and death.
Commentary: This study, while observational, suggests we have another tool to help establish risk for developing diabetes, heart disease and death. However, the authors do not suggest which patients this would be useful for, nor do these findings change the approach to patients at elevated risk. Modifying lifestyle factors is still key in this battle.
By: Spencer Blackman MD