Associations of inflammatory factors with glycaemic status among middle-aged and older Chinese people

Objective Low-grade chronic inflammation is associated with risk for type 2 diabetes. We investigated the associations between inflammatory factors and glycaemic status in a middle-aged and older Chinese population. Design A population-based cross-sectional study of 3289 residents aged 50-70 years from Beijing and Shanghai. Measurements C-reactive protein (CRP), interleukin-6 (IL-6) and soluble tumour necrosis factor α-receptor two (sTNFR2) were assayed. Results Comparing the highest with the lowest quartile of CRP, the odds ratio (OR) of diabetes was significantly higher in women [3·66 (95% CI 2·23-6·03)] than in men [1·51 (0·95-2·41)] (P for interaction = 0·004), while the increased OR for impaired fasting glucose (IFG) was only observed in women [OR 2·03 (1·44- 2·84)] (P for interaction = 0·022), after adjustment for age, geographic location, education, lifestyle factors, family history of diabetes, and use of antibiotics, aspirin and lipid-lowering drugs. The multiple-adjusted OR of IL-6 for diabetes was also higher in women [2·95 (1·78-4·90)] than in men [2·23 (1·39-3·59)] (P for interaction = 0·045). sTNFR2 was not associated with diabetes but inversely associated with IFG in men [OR 0·59 (0·41-0·85)] and women [OR 0·78 (0·56-1·09)] (P for interaction = 0·13). In addition, CRP was significantly associated with increased HbA_1c in both genders within euglycaemia after multiple adjustments. Conclusions Inflammatory markers are closely associated with diabetes and IFG in Chinese people. These associations appear to be stronger in women than in men. Furthermore, plasma CRP is positively associated with HbA_1c even in euglycaemic individuals.