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. . . In a prospective study, investigators followed 1321 nondiabetic adults to assess a possible relationship between the level of hemoglobin A1c (HbA1c) and the incidence of coronary heart disease. Hemoglobin A1c measures the percentage of glycated hemoglobin in a patient’s red blood cells. The HbA1c value provides a picture of a person’s average blood glucose control for the previous 2 to 3 months. The normal range for HbA1c in people without diabetes is 4% to 6%. For diabetics, the American Diabetes Association recommends that the HbA1c be maintained at 7.0% or less. The nondiabetic patients in the coronary heart disease study were followed for 8 to 10 years. In order to remove possibly confounding variables, when the data was analyzed, it was adjusted for age, race, sex, BMI, blood pressure, LDL cholesterol, HDL cholesterol, triglycerides and smoking status. The adjustments for these risk factors allowed the investigators to examine whether hyperglycemia might provide an independent risk factor for coronary heart disease. They found that when HbA1c was below 4.6%, the adjusted data showed no apparent relationship between glycemic control and an increased risk of coronary heart disease. However, as the HbA1c rose above 4.6%, the adjusted data showed that not only did the risk of coronary heart disease rise, but it did so at an ever-increasing rate. The study found that the risk of coronary heart disease in nondiabetics rose 2.4-fold with every 1% increase in HbA1c above 4.6%. Findings similar to those seen in both of these studies have also been reported by other investigators, and references can be found within each paper. However, it is important to remember that correlation does not equal causation. The relationship between increased blood glucose in nondiabetics and the incidence of cancer or the incidence of coronary heart disease may rest upon variables that are not as yet defined. However, it is worth noting that it may be important even for nondiabetics to keep an eye on their fasting blood glucose and their HbA1c. |
I would also note that they’re talking about increases in relative risk, as opposed to absolute risk. Those of us who point that out when looking at studies of the association between statin therapies and reduction of cardiovascular risk need to be aware of it when used in other contexts, as well.