The Association of Percent Body Fat and Lean Mass With HbA(1c) 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 (HbA(1c)) 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 HbA(1c). 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 HbA(1c); odds ratios per 5% increment for the association of percent body fat with HbA(1c) >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 HbA(1c) in males age <40 years and higher trunk fat was associated with higher HbA(1c) in females across age categories. CONCLUSIONS: Lifestyle interventions to lower HbA(1c) should consider targeting both weight loss and body composition.