The Association of Percent Body Fat and Lean Mass With HbA1c in US Adults

Context Body fat and body composition distribution patterns affect diabetes risk and glycemic control, but most studies use proxy measures (e.g., body mass index). Objective This study examined the association of percent body fat and lean mass with glycated hemoglobin (HbA1c) in US adults. Design The National Health and Nutrition Examination Survey (NHANES) is a program of cross-sectional studies that enroll nationally representative samples of the US civilian noninstitutionalized population. Setting NHANES is designed to assess the health status of adults and children throughout the United States. Participants This study included 11,125 participants aged 18 to 69 years from the 1999 through 2006 NHANES, comprising 846 persons with diagnosed diabetes and 10,125 without diabetes. Main Outcome Measures Total and abdominal (trunk) percent body fat and lean mass were measured using dual-energy x-ray absorptiometry. Linear and logistic regression analyses were used to examine their association with HbA1c. Results Among those without diagnosed diabetes, total and trunk percent body fat, as well as trunk and total lean mass, were strongly associated with elevated HbA1c; odds ratios per 5% increment for the association of percent body fat with HbA1c >5.7% (39 mmol/mol) ranged from 1.60 to 2.01 across age and sex categories. Among adults with diabetes, higher total percent fat was associated with higher HbA1c in males age <40 years and higher trunk fat was associated with higher HbA1c in females across age categories. Conclusions Lifestyle interventions to lower HbA1c should consider targeting both weight loss and body composition.