Association between Percent Body Fat and Hemoglobin A1c in Non-Anemic, Non-Smoking Korean Adults: A Cross-Sectional Study Using Data from the Korea National Health and Nutrition Examination Survey 2022–2023

Background: Hemoglobin A1c (HbA1c) is a key glycemic biomarker; however, non-glycemic factors like hemoglobin (Hb) levels can act as confounders.Additionally, body mass index (BMI) cannot differentiate fat mass from fat-free mass.This study aimed to evaluate the independent association between percent body fat (PBF) and HbA1c in non-anemic, non-smoking adults, adjusting for confounders including fasting glucose and Hb.Methods: This cross-sectional study analyzed 5,167 non-diabetic, non-anemic, non-smoking adults (≥20 years) from the Korea National Health and Nutrition Examination Survey 2022-2023.Weighted multiple linear regression models were adjusted for age, fasting glucose, Hb, education, income, alcohol consumption, and physical activity.BMI-stratified subgroup analyses excluded fasting glucose to assess the total association between PBF and HbA1c.Results: In multivariable-adjusted models, HbA1c was higher in the highest PBF tertile versus the lowest in males (β=0.091;95% confidence interval [CI], 0.059-0.123)and females (β=0.063;95% CI, 0.038-0.089).PBF was positively associated with HbA1c across all fasting glucose quintiles, demonstrating a clear dose-response relationship across PBF deciles (P for trend<0.001).In subgroup analyses unadjusted for fasting glucose, these associations remained significant in obese males (BMI≥25 kg/m 2 ) and females with BMI≥20 kg/m 2 , but not in lower BMI categories.Conclusion: PBF is independently associated with HbA1c in non-anemic, non-smoking, Korean adults without diabetes, independent of the fasting glucose and Hb levels.These findings suggest that body fat, in addition to BMI, may be relevant to glycemic regulation and metabolic health in this group.