Relationships between sarcopenic obesity and insulin resistance, inflammation, and vitamin D status: The Korean Sarcopenic Obesity Study

Objective: It has been suggested that insulin resistance, low-grade inflammation and vitamin D deficiency are associated with obesity and sarcopenia. However, their relationships with sarcopenic obesity (SO) are unclear. We evaluated the impact of homoeostasis model assessment of insulin resistance (HOMA-IR), high-sensitivity C-reactive protein (hsCRP) and 25-hydroxyvitamin D (25[OH]D) levels on SO in Korean adults. Study subject/measurements This study included 493 apparently healthy adults (180 men and 313 women) enrolled in the Korean Sarcopenic Obesity Study. Sarcopenia was defined as a skeletal muscle mass index (SMI) of 1 SD below the sex-specific mean value for a young reference group. Obesity was defined as a visceral fat area (VFA) ≥100 cm². We classified the participants into four sarcopenia/obesity groups based on both SMI and VFA. Results: The prevalence of SO was 17.8% in men and 24.9% in women. In women, the SO group had higher HOMA-IR and hsCRP levels compared with the non-SO group. In men, the 25[OH]D levels were significantly lower in the SO group than the non-SO group. Both hsCRP and HOMA-IR levels were negatively correlated with SMI and positively correlated with VFA in both men and women, whereas 25[OH]D levels were positively correlated with SMI in both men and women. Multiple binary logistic regression analysis showed that HOMA-IR and 25[OH]D levels were independently associated with SO in men, while HOMA-IR and hsCRP were significant factors predicting SO in women. Conclusion Insulin resistance, inflammation and vitamin D deficiency were associated with SO in a Korean adult population.