Longitudinal Changes of Body Composition Phenotypes and Their Association with Incident Type 2 Diabetes Mellitus during a 5-Year Follow-up in Koreans

BACKGROUND: To elucidate longitudinal changes of complex body composition phenotypes and their association with incident type 2 diabetes mellitus. METHODS: A total of 17,280 (mean age, 48.1±8.2 years) Korean adults who underwent medical check-ups were included. The mean follow-up duration was 5.5±0.5 years. Body compositions were assessed using a bioelectrical impedance analysis. Four body composition phenotypes were defined using the median of appendicular skeletal muscle mass (ASM) index and fat mass index: low muscle/low fat (LM/LF); high muscle (HM)/LF; LM/high fat (HF); and HM/HF groups. RESULTS: Of the individuals in the LM/LF or HM/HF groups, over 60% remained in the same group, and over 30% were moved to the LM/HF group. Most of the LM/HF group remained in this group. In the baseline HM/LF group, approximately 30% stayed in the group, and the remaining individuals transitioned to the three other groups in similar proportions. Incident diabetes was significantly lower in participants who remained in the HM/LF group than those who transitioned to the LM/LF or LM/HF group from the baseline HM/LF group in men. ASM index was significantly associated with a decreased risk for incident diabetes in men regardless of obesity status (adjusted odds ratio [OR], 0.71 per kg/m(2); 95% confidence interval [CI], 0.52 to 0.97 in non-obese) (adjusted OR, 0.87; 95% CI, 0.77 to 0.98 in obese) after adjusting for other strong risk factors (e.g., baseline glycosylated hemoglobin and homeostasis model assessment of insulin resistance). CONCLUSION: Maintenance of ASM may be protective against the development of type 2 diabetes mellitus in men, regardless of obesity status.