Homeostasis model assessment of insulin resistance in a general adult population in Korea: additive association of sarcopenia and obesity with insulin resistance.

BACKGROUND: Insulin resistance (IR) is a major factor associated with type 2 diabetes. Using homeostasis model assessment of insulin resistance (HOMA-IR), we aimed to elucidate the factors associated with IR risk, especially the cumulative effect of obesity and sarcopenia on IR.

METHODS: A total of 8,707 adults from the fourth and fifth Korean National Health and Examination Surveys were studied. Laboratory, anthropometric and lifestyle factors were analysed to reveal their association with HOMA-IR and IR risk. Subjects were divided into four groups according to the presence of obesity and sarcopenia to identify their effect on IR risk.

RESULTS: We found that high triglycerides and alanine aminotransferase, low high-density lipoprotein cholesterol, obesity and sarcopenia were independent risk factors for IR in both sexes. Obese men with sarcopenia had a significantly higher risk of IR than men who were obese or sarcopenic (but not both). The additive effect of sarcopenia with obesity on IR risk was not observed in women. Cut-offs of HOMA-IR for determining IR were calculated as 75 percentile value of young healthy subpopulation, 2·19 in men and 2·18 in women. These cut-offs could distinguish individuals with impaired fasting glucose from normal ones, with a sensitivity of 65·4% (men) and 73·3% (women), and a specificity of 68·8% (men) and 69·4% (women).

CONCLUSION: These data showed that obese men with sarcopenia exhibited a significantly higher IR risk than obese, nonsarcopenic men. In women, body composition did not affect IR if they were already obese.