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This study investigates why non-Hispanic Blacks (NHB) show higher stable HbA1c than non-Hispanic Whites (NHW) despite similar blood glucose levels.

June 7, 2026

2947-LB: Labile HbA1c (L-HbA1c) and the Mystery of Higher HbA1c in Non-Hispanic Blacks (NHB) vs. Non-Hispanic Whites (NHW) Independent of Blood Glucose

Key Points

This study investigates why non-Hispanic Blacks (NHB) show higher stable HbA1c than non-Hispanic Whites (NHW) despite similar blood glucose levels.
Recruited self-identified NHB and NHW youth with Type 1 diabetes for ≥6 months, aged >5 years, from a pediatric clinic.
Collected stable HbA1c and labile HbA1c via cation exchange HPLC and analyzed alongside continuous glucose monitoring data.
Used analysis of covariance to assess the impact of race, blood glucose metrics, gender, and age on HbA1c levels.
Stable HbA1c was significantly higher in NHB compared to NHW patients (p=0.0246) after controlling for mean blood glucose.
Strong correlations found between stable HbA1c and mean blood glucose (r=0.76, p<0.0001) and time in range (r=-0.65, p<0.0001).
No racial differences were found in labile HbA1c, despite its significant association with concurrent blood glucose levels (p=0.0001).

Abstract

Introduction and Objective: Higher levels of stable HbA1c have been repeatedly observed for NHB compared to NHW patients at any given level of mean blood glucose (MBG). L-HbA1c, the reversible precursor to stable HbA1c, is a product of non-enzymatic hemoglobin glycation that reflects short-term variations in blood glucose concentration. Potentially higher levels of stable HbA1c are due to formation of higher levels of the labile precursor. We hypothesized that L-HbA1c, measured by cation exchange HPLC, would be higher in NHB vs. NHW youth with Type 1 diabetes (T1D) when controlled for concurrent blood glucose (CBG). Methods: Self-identified NHB and NHW patients with T1D for ≥6 months, aged 5 years, using continuous glucose monitoring (CGM) were recruited from our pediatric diabetes clinic. Stable and L-HbA1c were collected and analyzed within 8 hours using Bio-Rad V2TURBO. CGM-derived MBG and time in range (TIR) for 14 days prior were recorded. CBG was collected at the same time as HbA1c and measured in the clinical lab. Analysis of covariance was performed with race, CBG or MBG along with gender and age as independent variables. Results: Thirty self-identified NHB patients and twenty-nine NHW patients were enrolled. Stable HbA1c strongly correlated with MBG (r=0.76, p0.0001) and TIR (r=-0.65, p0.0001). L-HbA1c correlated significantly with CBG (r=0.83, p0.0001) and stable HbA1c (r=0.39, p=0.002). Stable HbA1c was higher in NHB (p=0.0246) after controlling for MBG or CBG and other covariates. Although L-HbA1c was significantly associated with CBG (p=0.0001) there was no racial difference. Conclusion: Previous observations of higher stable HbA1c in NHB vs NHW independent of MBG were confirmed. Although L-HbA1c was significantly correlated with CBG there was no difference between NHB and NHW patients. These findings suggest that glucose concentration-independent racial variation in stable HbA1c is not due to variation in the labile precursor of HbA1c. Disclosure B. McConaughey: None. S. Chalew: None. R. Gomez: Research Support; Current; Ascendis Pharma A/S, Lumos, Egetis. G. Love: None. P. Quebedeaux: None.

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