The influence of waist circumference on insulin resistance and nonalcoholic fatty liver disease in apparently healthy Korean adults

BACKGROUND/AIMS: Waist circumference (WC) is a risk factor for metabolic syndrome and is related to insulin resistance (IR) and nonalcoholic fatty liver disease (NAFLD). The purpose of this study was to determine the association between WC and IR and NAFLD in apparently healthy Korean adults. METHODS: The volunteers included in this cross-sectional study comprised 9,159 adults (5,052 men, 4,107 women) who participated in a comprehensive health checkup program. IR was evaluated by the homeostasis model assessment of IR (HOMA-IR) and was considered to be present when the HOMA-IR score was >2. NAFLD was evaluated by ultrasound examination. Elevated alanine aminotransferase (ALT) was defined as >40 IU/L in men and >35 IU/L in women. Logistic regression was performed to determine the odds ratios (ORs) and 95% confidence intervals (95% CIs) for NAFLD, IR, and ALT according to categorized levels of WC. RESULTS: NAFLD was found in 2,553 (27.9%) of the participants (82.6% men, 17.4% women), while IR and elevated ALT were found in 17.2% (68.1% men, 31.9% women) and 10% (83% men, 17% women), respectively. After adjusting for confounding factors, the prevalence of NAFLD, IR, and elevated ALT was significantly associated with increases in WC quartile: highest quartile for NAFLD in men, OR=15.539, 95% CI=12.687-19.033; highest quartile for NAFLD in women, OR=48.732, 95% CI=23.918-99.288 (P<0.001); and highest quartile for IR in men, OR=17.576, 95% CI=13.283-23.255; highest quartile for IR in women, OR=11.078, 95% CI=7.813-15.708 (P<0.001); highest quartile for elevated ALT in men, OR=7.952, 95% CI=6.046-10.459; and highest quartile for elevated ALT in women, OR=8.487, 95% CI=4.679-15.395 (P<0.001). CONCLUSIONS: WC contributes to IR and NAFLD in apparently healthy Korean adults, and thus may be an important factor in the development of IR and NAFLD.

The Relationship of Body Composition and Coronary Artery Calcification in Apparently Healthy Korean Adults

BACKGROUND: We investigated the association of coronary artery calcium score (CACS) with body composition and insulin resistance in apparently healthy Korean adults. METHODS: Nine hundred forty-five participants (mean age, 48.9 years; 628 men) in a medical check-up program were selected for analysis. Body composition was assessed by bioelectrical impedance analysis (BIA). Insulin resistance was evaluated using the homeostasis model assessment of insulin resistance (HOMA-IR). The CACS was assessed by multidetector computed tomography. RESULTS: One hundred forty-six subjects (15.4%) showed coronary artery calcification and 148 subjects (15.7%) had metabolic syndrome. CACS showed a significant positive correlation with age, fasting glucose level, waist circumference (WC), blood pressure, hemoglobin A1c, HOMA-IR, and waist-hip ratio (WHR) assessed by BIA. CACS had a negative correlation with high density lipoprotein cholesterol (HDL-C). Subjects with high CACS showed significantly higher mean WHRs and lower mean values for lean body mass compared with subjects without coronary artery calcification. In logistic regression analyses with coronary artery calcification as the dependent variable, the highest quartile of WHR showed a 3.125-fold increased odds ratio for coronary artery calcification compared with the lowest quartile after adjustment for confounding variables. When receiver operating characteristics analyses were performed with coronary artery calcification as the result variable, WHR showed the largest area under the curve (AUC) value among other variables except for age and WC in women (AUC=0.696 for WHR, 0.790 for age, and 0.719 for WC in women). CONCLUSION: In our study population of apparently healthy Korean adults, WHR was the most significant predictor for coronary artery calcification among other confounding factors, suggesting that it may have implication as a marker for early atherosclerosis.