A1C Combined With Glycated Albumin Improves Detection of Prediabetes in Africans: The Africans in America Study

Abstract

Objective: Slowing the diabetes epidemic in Africa requires improved detection of prediabetes. A1C, a form of glycated hemoglobin A, is recommended for diagnosing prediabetes. The glycated proteins, fructosamine and glycated albumin (GA), are hemoglobin-independent alternatives to A1C, but their efficacy in Africans is unknown. Our goals were to determine the ability of A1C, fructosamine, and GA to detect prediabetes in U.S.-based Africans and the value of combining A1C with either fructosamine or GA.

Research design and methods: Oral glucose tolerance tests (OGTT) were performed in 217 self-identified healthy African immigrants (69% male, age 39 ± 10 years [mean ± SD], BMI 27.6 ± 4.5 kg/m(2)). A1C, fructosamine, and GA were measured. Prediabetes was diagnosed by American Diabetes Association criteria for glucose obtained from a 2-h OGTT. The thresholds to diagnose prediabetes by A1C, fructosamine, and GA were the cutoff at the upper tertile for each variable: ≥5.7% (39 mmol/mol) (range 4.2-6.6% [22.4-48.6 mmol/mol]), ≥230 µmol/L (range 161-269 µmol/L), and ≥13.35% (range 10.20-16.07%), respectively.

Results: Prediabetes occurred in 34% (74 of 217). The diagnostic sensitivities of A1C, fructosamine, and GA were 50%, 41%, and 42%, respectively. The P values for comparison with A1C were both >0.3. Combining A1C with either fructosamine or GA increased sensitivities. However, the sensitivity of A1C combined with fructosamine was not better than for A1C alone (72% vs. 50%, P = 0.172). In contrast, the sensitivity of A1C combined with GA was higher than for A1C alone (78% vs. 50%, P < 0.001).

Conclusions: As individual tests, A1C, fructosamine, and GA detected ≤50% of Africans with prediabetes. However, combining A1C with GA made it possible to identify nearly 80% of Africans with prediabetes.

Trial registration: ClinicalTrials.gov NCT00001853.