Should the hemoglobin A1c diagnostic cutoff differ between blacks and whites? A cross-sectional study

Area of Science:

• Ophthalmology
• Endocrinology
• Public Health

Background:

• Hemoglobin A1c (HbA1c) levels are typically higher in Black individuals than White individuals.
• The optimal diagnostic threshold for HbA1c may vary between racial groups, but this remains unclear.

Purpose of the Study:

• To compare the relationship between HbA1c levels and the prevalence of retinopathy in Black and White U.S. adults.
• To determine if HbA1c diagnostic thresholds for retinopathy risk should differ by race.

Main Methods:

• Cross-sectional study using a nationally representative sample from the National Health and Nutrition Examination Survey (2005-2008).
• Included 2804 White and 1008 Black adults aged 40+ in the U.S.
• Logistic regression and restricted cubic spline models analyzed retinopathy prevalence against HbA1c levels, stratified by race.

Main Results:

• Retinopathy prevalence significantly increased at HbA1c levels of 6.0%-6.4% for White persons and 5.5%-5.9% for Black persons.
• Restricted cubic spline models indicated an increased risk for retinopathy at lower HbA1c levels in Black individuals compared to White individuals.
• Adjustments were made for age, sex, hypertension, BMI, family history of diabetes, and diabetes medication use.

Conclusions:

• Retinopathy risk begins to increase at a lower HbA1c level in Black Americans than in White Americans.
• Current findings do not support adjusting the diagnostic threshold of HbA1c for Black individuals.
• Further research is needed to understand the impact of duration at specific HbA1c levels.