New Guidelines on Heart Disease Prevention and Diabetes – A1C
I mentioned in an earlier post that the American Diabetes Association and American Heart Association have just released an update on the prevention of heart disease in adults with type 2 diabetes. Since heart disease is so incredibly important and so connected to diabetes, I want to be sure you have the most current information on prevention. And, nothing could emphasize the connection between diabetes and heart disease more that this report’s stronger emphasis on A1C.
A1C, also called hemoglobin A1C or HbA1C, is a blood test that correlates with our average blood glucose levels over a period of a few months. So, where our blood glucose meter gives us only a “snapshot” of one particular point in time, A1C is a 3 month “movie” about blood glucose control. The American Diabetes Association sets an A1C goal of 7% for people with diabetes, which correlates with an average blood glucose level of about 154 milligrams per liter.
These new guidelines validate recent changes for using A1C for the diagnosis of diabetes and prediabetes, and re-emphasize the importance of blood glucose control, as measured by A1C, to the prevention of heart disease as a diabetes complication. In fact, one reason these organizations are supporting A1C to diagnose prediabetes is the association with an increased risk for heart disease even when A1C levels range between 5.7% and 6.4% (the prediabetes range). This association with the risk for complications is, in some cases, stronger with A1C values than with the traditional fasting blood glucose tests.
The story on how reducing higher A1C levels might reduce the risk for heart disease in people with longer term type 2 diabetes is still not completely clear, however. Some studies involving “intensive” blood glucose control to push A1C levels below 7% could not demonstrate a significant benefit to heart disease risk, but noted increased incidences of severe hypoglycemia (low blood glucose). So, while studies do demonstrate a connection between higher A1C and heart disease (every 1% increase in A1C increases the risk of a cardiovascular “event” by 18%), intensive efforts to lower A1C below 7% in many people with type 2 diabetes does not have a clear “pay off.”
The important point is that all of the recommendations in these new guidelines, including this reinforced emphasis on blood glucose control – A1C – are based upon recent research like analyses of data from the Atherosclerosis Risk in Communities Study (ARIC). And, the “take home” messages for us about A1C are that blood glucose control is still very important for reducing our risks for heart disease, but intensive efforts to lower A1C is a case-by-case medical decision based upon disease duration, life expectancy, presence of existing heart disease, age, and the risk for severe hypoglycemia in treatment.
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