Factors Associated with Glycated Hemoglobin across Body Mass Index Categories in Korean Adults: A Secondary Analysis of the Ninth (2023) Korea National Health and Nutrition Examination Survey

Purpose : This study examined the association between body mass index (BMI) and glycated hemoglobin (HbA1c) levels and identified factors associated with HbA1c across BMI categories among Korean adults aged 19 years and older without diagnosed diabetes or hypertension.Methods : Data from 3,490 adults who participated in the 2023 Korea National Health and Nutrition Examination Survey were analyzed. Participants were classified into four BMI categories: under-weight (‹18.5kg/m²), normal-weight (18.5-22.9kg/m²), over-weight (23.0- 24.9kg/m²), and obese (≥25.0kg/m²). Multiple linear regression analyses were conducted using IBM SPSS Statistics version 29.0 to identify factors associated with HbA1c levels.Results : Mean HbA1c levels differed significantly across BMI categories (F=13.44, <i>p</i> ‹.001), with the highest level observed in the obese group (5.41±0.35%) compared with the under-weight (5.28±0.56%) and normal-weight (5.31±0.45%) groups. Older age was associated with higher HbA1c levels in all BMI categories (under-weight: <i>β</i>=.49; normal-weight: <i>β</i>=.34; over-weight: <i>β</i>=.52; obese: <i>β</i>=.40; all <i>p</i> ‹.001). In the normal-weight group, greater carbohydrate intake was associated with higher HbA1c levels (<i>β</i>=.08, <i>p</i> =.006). In the obese group, elevated triglyceride levels (<i>β</i>=.06, <i>p</i> =.046) and lower high-density lipoprotein cholesterol levels (<i>β</i>=-.13, <i>p</i> ‹.001) were significantly associated with HbA1c levels.Conclusion : These findings suggest that diabetes prevention strategies for individuals without a diagnosis of diabetes should extend beyond a weight-centered approach and incorporate age, dietary carbohydrate intake, lipid management, and tailored screening approaches across all BMI categories, including under-weight and normal-weight individuals.