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Randomized Controlled Trial
. 2024 Dec 1;47(12):2155-2163.
doi: 10.2337/dc24-1362.

Relationship Between Average Glucose Levels and HbA1c Differs Across Racial Groups: A Substudy of the GRADE Randomized Trial

David M Nathan  1 , William H Herman  2 , Mary E Larkin  1 , Heidi Krause-Steinrauf  3 , Hiba Abou Assi  4 , Andrew J Ahmann  5 , Janet Brown-Friday  6 , Daniel S Hsia  7 , Tasma Harindhanavudhi  8 , Mary Johnson  9 , Valerie L Arends  10 , Nicole M Butera  3 , Samuel P Rosin  3 , John M Lachin  3 , Naji Younes  3 ; GRADE Study Research Group
Collaborators, Affiliations
Randomized Controlled Trial

Relationship Between Average Glucose Levels and HbA1c Differs Across Racial Groups: A Substudy of the GRADE Randomized Trial

David M Nathan et al. Diabetes Care. .

Abstract

Objective: To determine whether the relationship between average glucose (AG) levels and hemoglobin A1c (HbA1c) differs across racial/ethnic groups.

Research design and methods: We performed a prospective substudy of GRADE, a comparative effectiveness randomized trial conducted in 36 centers in the U.S. A total of 1,454 of the 5,047 participants in the GRADE cohort, including 534 non-Hispanic White (NHW), 389 non-Hispanic Black (NHB), and 327 Hispanic White patients and 204 patients of other racial/ethnic backgrounds, were included in the substudy. Continuous glucose monitoring (CGM) performed for 10 days was used to calculate AG10. Immediately after CGM, HbA1c and glycated albumin were measured. Fasting plasma glucose (FPG) and glucose area under the curve (AUC) were derived from a 75-g oral glucose tolerance test.

Results: The relationship between AG10 and HbA1c was significantly different for NHB compared with NHW patients and those of other racial/ethnic groups. HbA1c levels were 0.2-0.6 percentage points higher in NHB than in NHW patients for AG10 levels from 100 to 250 mg/dL. For an HbA1c of 7%, AG10 was 11 mg/dL higher for NHW than for NHB patients. Similar findings were observed across races for relationships of FPG and AUC with HbA1c and for glucose measurements with glycated albumin levels. Differences in the relationship between AG10 and HbA1c across racial groups remained after adjustments for any demographic or other differences between racial/ethnic subgroups.

Conclusions: The relationship between several measures of glucose with HbA1c and glycated albumin consistently differed across races. These findings should be considered in setting treatment goals and diagnostic levels.

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Conflict of interest statement

Duality of Interest. H.A.A. reports grants from Novo Nordisk to the institution for a multisite clinical trial, payment or honoraria for an HCPLive Institutional Perspectives in Diabetes Presentation in June 2022, and stock or stock options from Pfizer and Medtronic, outside the submitted work. J.B.-F. reports leadership roles with the American Diabetes Association as a board member and current president of health and education (2023). D.S.H. has conducted clinical trials through contracts with Novo Nordisk and Eli Lilly, with payments made to the institution, outside of the submitted work. M.J. reports research grants from Abbott Laboratories and Dexcom made directly to HealthPartners Institute, outside of the submitted work. No other potential conflicts of interest relevant to this article were reported.

References

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