1295-P: Fasting Plasma Glucose and A1C Underperform as Diagnostic Tests for Africans with Diabetes—Insight from the Africans in America Study

According to the International Diabetes Federation, the prevalence of type 2 diabetes (DM) in sub-Saharan Africa will increase by 134% in the next 25 years. Furthermore, recent data suggests that the most widely used diagnostic tests, fasting blood glucose (FPG) (≥126 mg/dL) and A1C (≥6.5%) underperform in Africans. Thus, rigorous testing by the OGTT for the detection of DM in Africans is critical. The OGTT allows for assessment of 2h glucose, a postprandial equivalent. Therefore, OGTT were performed in 601 African-born Blacks enrolled in the Africans in America cohort (male: 63% (377/601), age: 39±11, (mean±SD) range 20-69, BMI: 27.7±4.5, range (18.2-42.0)). DM diagnosis was based on ADA glucose criteria for the OGTT. To determine if confounding factors were present, tests were done to assess hemoglobin, hemoglobin type, nutritional status and renal and hepatic function. Assays for G6PD deficiency were performed in 228 consecutively enrolled participants. DM occurred in 7% (42/601) of participants. Sickle cell trait (SCT) or HbC Trait occurred in 17% (100/601) of participants overall and 33% (14/42) of individuals with DM. No participants (0/601) had anemia (Hgb<11 g/dL), nutritional deficiencies or renal or hepatic dysfunction. G6PD deficiency was identified in 10% (22/228) of participants overall, and no one with DM (0/18). Diagnostic sensitivity of FPG for the detection of DM was 16% (7/42). Sensitivity of A1C was 28% (12/42). Sensitivity of both tests combined was 33% (14/42). When the Africans with SCT or HbC trait were excluded, sensitivity of FPG was 21% (6/28) and A1C was 29% (8/28). For both tests combined, the sensitivity increased to only 36% (10/28). In short, FPG and A1C underperform in the detection of DM in Africans even in the absence of SCT, HbC trait and metabolic disorders and nutritional deficiencies. This data raises concern that the DM epidemic in Africa may be worse than predicted.