Your Glycated Hemoglobin (HbA1c) Predicts Cardiovascular Risk

In January I blogged about the call for hemoglobin A1c – also known as glycated hemoglobin or HbA1c – to be used as the standard test for diagnosing diabetes.  Thus type 2 diabetes would be diagnosed in persons with an HbA1c of 6.5% or greater, without the need for blood glucose testing.  Further support for wider use of HbA1c has now been published in the New England Journal of Medicine.

Johns Hopkins researchers measured HbA1c and fasting blood glucose levels in 11,000 healthy adults in 1990-1992, and followed them for an average of 14 years.

The subjects were classified into 5 groups (quintiles) according to their HbA1c levels: below 5%, 5% - 5.5%, 5.5% to 6%, 6% to 6.5%, or above 6.5%.  The risk of occurrence during follow-up for diabetes, coronary heart disease events (heart attack, severe angina, sudden cardiac death), and all-cause death was significantly increased in the three HBA1c groups above the 5.5% point; ischemic stroke was increased above the 6% level.  The higher the HbA1c group, the higher the incidence of the condition – with one exception.  The risk of all-cause mortality formed a J-shaped curve, with the lowest and highest HbA1c levels being predictive of death.

The analysis results were unchanged after corrections made for differences between the groups in gender, age, race, family history of disease, lifestyle factors, lipid levels, and fasting glucose levels.  This clearly shows that HbA1c levels, especially above 6.0%, are better than fasting glucose for predicting long-term cardiovascular risk. And we know from other studies that HbA1c is superior to fasting glucose for diagnosis of type 2 diabetes.  It behooves people over 50 to get up to speed on the HbA1c test and its meaning.