Sickle cell trait may alter the relationship between A1C and glycemia: a preliminary report from the Africans in America cohort
Jean Nepo Utumatwishima1,&, David Sacks1, Anne Sumner1
1National Institutes of Health, Bethesda, Maryland, USA
Jean Nepo Utumatwishima, National Institutes of Health, Bethesda, Maryland, USA
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).
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.
HbA1Clevels in the HbAS and HbAA groups were: 5.6±0.5 vs. 5.4±0.4,
P = 0.02. In the HbAS and HbAA groups, the respective correlations between
HbA1c and FPG were: 0.56 vs. 0.12, P = 0.02. The correlations between HbA1C
and 2h glucose in the two groups were: 0.59 vs. -0.11, P < 0.01. The correlations
between HbA1C and AUC-glucose in each group were: 0.60 vs. -0.03, P < 0.01.
the significant difference in correlation between HbA1C and each glycemic measure, suggests that the relationship between HbA1C and glucose concentration varies according to HbAS status. Therefore, the efficacy of HbA1C and even diagnostic thresholds for HbA1C may need to be sickle cell trait-specific. Due to the magnitude of the diabetes epidemic and the high prevalence of HbAS in Africa, these findings need additional exploration in a larger cohort.
The 3rd Africa Diabetes Congress, Yaounde, Cameroon (Yaounde)