Associations of Obesity-metabolic Status With Insulin Resistance and Chronic Inflammation Level: Results From the CNTR Study

Background: Insulin resistance (IR) and inflammation are the potential mechanism linking obesity and cardiometabolic risk. The aim of this work was to examine the joint relations of obesity and metabolic status with IR and chronic inflammation level among Chinese adult twins. Methods: The analyses used data from 1113 adult twins in 4 provinces (Shandong, Zhejiang, Jiangsu and Sichuan) from Chinese National Twin Registry (CNTR) which collected detailed information. Those with 0 or 1 metabolic syndrome (MetS) components excluding waist circumference were considered metabolically healthy, and those with waist circumference≥90 cm in men and ≥85 cm in women as obese. All participants were categorized into four phenotypes: metabolically healthy non-obesity (MHNO), metabolically healthy obesity (MHO), metabolically unhealthy non- obesity (MUNO), metabolically unhealthy obesity (MUO). High sensitivity C reactive protein (hsCRP) was measured to assess underlying inflammation and homeostasis model assessment of insulin resistance (HOMA-IR) was calculated as surrogate measure of insulin resistance. Results: In observational analyses of 1113 individuals (mean [SD] age, 46.6 [12.9] years; 463 obese [41.6%]). 20.3% obese twins were metabolic healthy. Serum HOMA-IR level was higher in MUNO (β=0.42, 95% CI: 0.21–0.64), MHO (β=0.68, 95% CI: 0.36–1.00) and MUO (β=0.69, 95% CI: 0.46–0.91) twins, compared with their MHNO counterparts. The chronic inflammation level, evaluated by hsCRP was similar between MHO and MUO, which differed significantly to metabolic healthy non-obesity (MHNO). Within twin-pair analysis indicated there might exist common genetic influence between HOMA-IR and MHO/MUO phenotype. Conclusions: Among Chinese adult twins, metabolic status were independently associated with higher IR while development of chronic inflammation might closely relate to central obesity. It is necessary for the different risk assessment based on metabolic status in obese population.