Correlation of Waist Circumference-Mediated Glycosylated Hemoglobin Levels With New-Onset BADL Disability.

BACKGROUND: Impairment in basic activities of daily living (BADLs) is strongly associated with chronic disease. Glycosylated hemoglobin (HbA1c) reflects long-term glycemic control and is related to several chronic diseases and central obesity. However, the relationship between HbA1c and BADL disability remains unclear. This study examined the association between HbA1c levels and new-onset BADL disability and explored the mediating role of waist circumference. METHODS: A longitudinal research design was used to obtain data from the China Health and Retirement Longitudinal Study (CHARLS). This study included 4318 middle-aged and older adults without BADL disability at baseline (2011), and they were followed up until 2020. Participants were categorized into quartiles based on baseline HbA1c levels (Q1-Q4). The Kaplan-Meier curves, Cox regression, and restricted cubic splines were used to assess the association between HbA1c levels and new-onset BADL disability. Mediation analysis was employed to evaluate the role of waist circumference. RESULTS: During an average follow-up period of 8.19 years, the hazard ratios (HRs) for BADL disability were higher in the Q1, Q2, and Q4 groups than in the Q3 group (p < 0.05). Each 1-unit increase in HbA1c was associated with an 11% higher risk of BADL disability (HR: 1.11; 95% CI: 1.02-1.20). A nonlinear threshold effect was observed at HbA1c levels of 5.2%, with a significant increase in the risk of BADL disability beyond this threshold (HR: 1.23; 95% CI: 1.13-1.33). Mediation analysis showed that waist circumference accounted for 20% of the overall effect of HbA1c levels on the risk of BADL disability. CONCLUSION: Elevated HbA1c levels (particularly above 5.2%) predicted an increased risk of developing BADL disability, and waist circumference partially mediated the effect of HbA1c levels on BADL disability. These suggest that glycemic control with waist circumference management may be an important strategy for reducing the risk of BADL disability.