Insulin resistance is associated with C-reactive protein independent of abdominal obesity in nondiabetic Taiwanese

Abstract

Insulin resistance, which plays a fundamental role in the pathogenesis of metabolic syndrome and type 2 diabetes mellitus, is associated with serum levels of inflammatory markers and abdominal obesity. Whether insulin resistance is caused by inflammation or is an epiphenomenon of obesity remains unresolved. We therefore conducted a cross-sectional study to investigate whether the association between insulin resistance and C-reactive protein (CRP) levels is independent of abdominal obesity in a nondiabetic Taiwanese population. The study included 574 Taiwanese participants (300 men and 274 women) who were nondiabetic persons with CRP levels not exceeding 10 mg/L and who did not have a history of cardiovascular disease or were taking medication for dyslipidemia. All participants were of Han-Chinese origin. The degree of insulin resistance was determined using the homeostasis model assessment of insulin resistance (HOMA-IR). The CRP levels were categorized into quartiles from the lowest to the highest concentrations (Q1-Q4). Blood pressure, fasting glucose level, triglycerides level, waist circumference, and HOMA-IR were all found to be significantly higher in Q3 and Q4 than in Q1 and Q2. Stratified analysis by sex and abdominal obesity showed that HOMA-IR was significantly associated with CRP levels in both sexes in either obese or nonobese populations. Multiple linear regression analysis adjusting for age, smoking, components of metabolic syndrome, and waist circumference showed that the association between HOMA-IR and CRP levels remained significant in both men and women (P = .029 for men and P < .001 for women). These findings confirm that insulin resistance is strongly associated with CRP levels independent of abdominal obesity in nondiabetic Taiwanese. Factors other than abdominal obesity, such as polymorphisms in the CRP gene, may influence the association of insulin resistance with CRP levels in different ethnic populations.