Glycated Albumin Identifies Prediabetes Not Detected by Hemoglobin A1c: The Africans in America Study

Abstract

Background: Following immigration to the US, many Africans transition from a low-normal to a high-normal or overweight body mass index (BMI). This weight change is associated with a high rate of prediabetes in the nonobese. Studies in East Asians reveal that glycated albumin is effective in identifying prediabetes in nonobese Asians. Whether this is true in African immigrants is unknown. Therefore, we evaluated the ability of hemoglobin A_1c (Hb A_1c) and glycated albumin to detect prediabetes in nonobese (BMI <30 kg/m²) and obese (BMI ≥30 kg/m²) African immigrants.

Methods: Oral glucose tolerance tests (OGTTs) were performed in 236 self-identified healthy African immigrants [mean (SD) BMI 27.6 (4.4) kg/m²]. Prediabetes diagnosis was based on glucose criteria for the OGTT. Diagnostic sensitivity of Hb A_1c and glycated albumin was determined by thresholds at the upper quartile for each [Hb A_1c ≥5.7% (39 mmol/mol), glycated albumin ≥13.77%].

Results: Based on glucose criteria for the OGTT, prediabetes was detected in 36% (85/236). BMI and Hb A_1c were positively correlated (r = 0.22, P < 0.001), whereas BMI and glycated albumin were negatively correlated (r = -0.24, P < 0.001). Although the sensitivities of Hb A_1c and glycated albumin were similar in nonobese immigrants (37% vs 42%, P = 0.75), prediabetes was detected in 21 nonobese Africans by glycated albumin alone, in 18 by Hb A_1c alone, and in 4 by both tests. Therefore, sensitivity of the combined tests was better than for Hb A_1c alone(72% vs 37%, P < 0.01). In the obese, Hb A_1c was a much better diagnostic test than glycated albumin (64% vs 16%, P < 0.01) and combining the tests did not improve sensitivity (72% vs 64%, P = 0.50).

Conclusions: Glycated albumin contributes by identifying prediabetes not detected by Hb A_1c in nonobese African immigrants. ClinicalTrials.gov Identifier: NCT00001853.