1134-P: Determination of Glucose-Independent Racial Disparity in HbA1c in Youth with Type 1 Diabetes in the Era of Continuous Glucose Monitoring

Introduction: The extent and importance of higher HbA1c levels not due to mean blood glucose (MBG) in non-Hispanic Black (B) versus non-Hispanic White (W) individuals is controversial. We sought to clarify the relationship of HbA1c with metrics of glycemia derived from continuous glucose monitoring (CGM) in a young biracial population.

Methods: Glycemic data of 33 B and 85 W, otherwise healthy youth with type 1 diabetes (age 14.7±4.8 years, M/F=51/67, duration of diabetes 5.4±4.7 years) was derived from a factory calibrated CGM and compared with assayed HbA1c. Hemoglobin glycation index (HGI) a metric of MBG difference in HbA1c not due to MBG =assayed HbA1c - Glucose Management Index (GMI).

Results: B patients had higher unadjusted levels of HbA1c, MBG, MBGSD, GMI and HGI than W patients. Percent glucose time in range (TIR) and percent sensor use (PSU) were lower for B patients. HbA1c remained higher in B patients (8.6%) versus (7.7%) for W (p<0.0001) after statistical adjustment for MBG, MBGSD, age, gender, insulin delivery method and PSU. MBG and race accounted for 80% of the variation in HbA1c in the model. Results were similar when TIR was substituted for MBG (R²=0.64, p<0.0001). The 95% for HGI=0.47% in W patients, 52% of B patients had HGI ≥0.5%. Percent time below range was similar for both groups.

Conclusions: Young B patients have clinically relevant higher HbA1c (~0.9%) at any given level of MBG or TIR than W patients, which may pose an additional risk for diabetes complications. HGI ≥0.5% may be an easy way to identify high risk patients.