(HealthDay News) — For U.S.-based Africans, fasting plasma glucose (FPG) and hemoglobin A1c (A1C) in combination have higher sensitivity for abnormal glucose tolerance than either test alone, with no difference by variant hemoglobin status, according to a study published online Oct. 22 in Diabetes Care.

Anne E. Sumner, MD, from the National Institutes of Health in Bethesda, MD, and colleagues examined the sensitivities of FPG ≥5.6mmol/L, A1C ≥5.7%, and FPG combined with A1C for detection of abnormal glucose tolerance in U.S.-based Africans. Data were obtained from 216 African immigrants who underwent an oral glucose tolerance test.

The researchers found that 21% of the participants had variant hemoglobin. Thirty-three percent had abnormal glucose tolerance. The sensitivities of FPG were 32, 32, and 33%, respectively, for the total, normal, and variant hemoglobin groups. For A1C, the corresponding sensitivities were 53, 54, and 47%. The sensitivities were 64, 63, and 67%, respectively, for FPG and A1C combined. There was no variation in the sensitivities for FPG, A1C, and the combination based on hemoglobin status (all P>0.6). Sensitivity was higher for A1C than for FPG and for the combination vs. either test alone in the entire cohort (all P values ≤0.01).

“For the diagnosis of abnormal glucose tolerance in Africans, the sensitivity of A1C combined with FPG is significantly superior to either test alone,” the authors write.

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