Sickle cell trait may alter the relationship between A1C and glycemia: a preliminary report from the Africans in America cohort

Introduction: diabetes in Africa is reaching epidemic proportions. HbA1C, a form of glycated hemoglobin A (HbA), is used to diagnose and monitor diabetes. However, with sickle cell trait, hemoglobin type is HbAS rather than HbAA and HbA levels are 55% to 70% of normal. As the prevalence of HbAS is high in Africa, clarity on whether HbAS modifies the relationship between HbA1C and glycemia is necessary. Our goal was to match by age, sex and African region of origin, 48 African immigrants with HbAS to 48 African immigrants with HbAA, perform OGTT and compare the relationship of HbA1C to three glycemic measures: fasting plasma glucose (FPG), 2h glucose and area-under-curve for glucose (AUC-glucose). Methods: participants (67% male, age 40±11y (mean±SD), range 22-61y) were born in Africa (West 56%, Central 31%, East 13%), lived in Washington, DC and enrolled in the Africans in America cohort. OGTT were performed with glucose concentrations determined at 0, 0.5, 1h and 2h. On the same day hemoglobin electrophoresis and HbA1C levels were determined.