Fat‐to‐muscle ratio as a predictor of insulin resistance and metabolic syndrome in Korean adults

BACKGROUND: The present study evaluated the associations of the fat-to-muscle ratio (FMR) with metabolic syndrome (MetS) and insulin resistance (IR) in Korean adults using nationally representative survey data. METHODS: A two-stage stratified sampling method was reflected in a cross-sectional study involving a total of 13 032 participants aged >/= 19 years who participated in the fourth and fifth Korea National Health and Nutrition Examination Surveys. The homeostasis model assessment for IR (HOMA-IR) was used to evaluate IR and was calculated as follows: [fasting plasma glucose level (mg/dL) x fasting plasma insulin level (uIU/mL)]/405. MetS was defined using the 2006 International Diabetes Federation criteria, and FMR was measured using whole-body dual-energy X-ray absorptiometry and calculated as follows: total fat mass (kg) divided by total lean mass (kg). In addition, the optimal FMR cut-off values for detecting MetS and the odds ratios (ORs) for MetS risk were determined according to the FMR quartile and sex. RESULTS: Among all participants, the proportion of women was 58.4%, and the mean age was 44.22 +/- 0.26 years. The FMR significantly differed between men and women (0.30 +/- 0.002 vs. 0.53 +/- 0.003, respectively, P /= 3) were 5.35 [95% confidence interval (CI): 4.39-6.52], 7.67 (95% CI: 6.33-9.30), and 3.25 (95% CI: 2.70-3.92), respectively, in men and 5.59 (95% CI: 4.66-6.72), 7.48 (95% CI: 6.35-8.82), and 2.55 (95% CI: 2.17-3.00), respectively, in women. CONCLUSIONS: In the present study, a high FMR was significantly associated with the prevalence of MetS and IR. The present findings also showed that FMR can be a novel indicator for detecting the absence or presence of MetS, particularly in metabolically healthy normal-weight individuals and metabolically obese obese-weight individuals.