Proposed cutoff level of waist circumference in Japanese men: Evaluation by homeostasis model assessment of insulin resistance levels

Abstract

Objective The aim of this study is to propose the cutoff level of waist circumference (WC) on the basis of homeostasis model assessment of insulin resistance (HOMA-IR) levels in order to diagnose metabolic syndrome (MetS). Methods We examined a total of 798 non-diabetic men (40-65 years of age) by using a receiver operating characteristic (ROC) curve to determine the cutoff level that yielded the maximum sensitivity plus specificity. According to the criteria proposed by the International Diabetes Federation (IDF), and the Japanese Society of Internal Medicine (JSIM), subjects with ≥2 metabolic components other than abdominal obesity, were considered to have MetS. Results The overall prevalence rates of IDF- and JSIM-MetS were 17.4% (n=139) and 15.5% (n=124), respectively. The median levels of WC and HOMA-IR were 83.1 [interquartile range (IQR): 78.5-88.4] cm and 0.84 (IQR: 0.61-1.19), respectively. HOMA-IR was highly correlated with each metabolic parameter (each p< 0.05), and in addition, multiple linear regression analysis of HOMA-IR (adjusted R2=0.459) showed that WC level was the strongest independent predictors of HOMA-IR level (F=141.1, p<0.05). According to ROC curve analysis, the cutoff level of HOMA-IR for predicting IDF- and JSIM-MetS was 0.92 for both (sensitivity: 79.9% and 78.2%, specificity: 64.9% and 63.6%). Based on the HOMA-IR level, the proposed WC cutoff level was 82.7 cm (sensitivity: 75.4%, specificity: 63.8%). Conclusion This study suggests that WC level should be more strictly managed than current criteria, for preventing the development of MetS in non-diabetic middle-aged Japanese men. © 2012 The Japanese Society of Internal Medicine.