In 2010, the American Diabetes Association endorsed the use of hemoglobin A1c to diagnose type 2 diabetes, and fierce arguments over the wisdom of that move have ensued ever since. A 2013 debate at the American Association for Clinical Chemistry’s annual meeting featured a spirited dialogue on the merits of using HbA1c as a diagnostic marker, compared with the traditional—and still ADA-recommended—alternatives, fasting plasma glucose and two-hour plasma glucose.

Now the discussion is zeroing in on a narrower controversy within the HbA1c dispute—the role of race and ethnicity. African-Americans regularly have higher HbA1c values than do whites, even when they have similar fasting plasma glucose levels. Hispanics, too, have exhibited a similar HbA1c/FPG disparity, though amid a smaller body of research and to a lesser degree than is found among blacks. The questions are what this widely observed trend means and what to do about it.

Do higher HbA1c concentrations among blacks and Hispanics reflect socioeconomic or lifestyle factors, or are they driven by some as yet unidentified molecular or biological nonglycemic factors present in these patient populations? Should clinicians and laboratories set different diagnostic cutpoints for their black and Hispanic patients than for their white ones? Should laboratories seek race and ethnicity data to help overcome this apparent impediment to HbA1c interpretation?

My  cover story  in the December issue of CAP TODAY. Read the whole shebang.