Abstract P335: High-sensitive C-reactive Protein and Risk of Undiagnosed and Incident Diabetes: The Singapore Chinese Health Study

Abstract

Introduction: There has been growing evidence that elevated levels of C-reactive protein (CRP), as a biomarker of inflammation, are associated with increased risk of diabetes. However, previous prospective studies were mostly conducted among Caucasians, and few were done in Chinese. Thus, we assessed the hypothesis that elevated CRP levels are related to increased risk of type 2 diabetes among Chinese adults residing in Singapore. Methods: The Singapore Chinese Health Study (SCHS) is a population-based cohort that recruited 63,257 Chinese adults aged 45-74 years during 1993 and 1998, and morning blood samples were collected from about 32,000 participants during the first follow-up visit (1999-2004). In this diabetes case-control study nested within SCHS, all eligible participants were free of diagnosed diabetes, cardiovascular disease and cancer at blood collection, and 571 cases subsequently reported to have diabetes at the follow-up II visit (2006-2010), while 571 controls were matched to cases for age (±3 years) and date (±6 months) of blood collection, sex and dialect group and remained free of diabetes, cardiovascular disease at the follow-up II visit. Plasma high-sensitive CRP (hs-CRP) concentrations were assayed, and conditional logistical regression models were used to calculate the odds ratios (ORs) and 95% confidence intervals (CIs). Results: The mean (SD) concentrations of hs-CRP was 2.79 (2.65) and 1.86 (2.03) mg/L, respectively, in cases and controls (P<0.001). After controlling for matching factors, education level, smoking status, alcohol intake, physical activity, baseline hypertension, fasting status, body mass index, triglycerides and HDL cholesterol, the ORs (95% CIs) across quartiles of hs-CRP were 1.00 (ref), 1.25 (0.79-1.98), 1.23 (0.78-1.95), and 1.73 (1.11-2.69; P for trend=0.01). Among the cases, there were 279 subjects who had HbA1C ≥6.5% at the time of blood collection and thus classified as undiagnosed diabetes, and the other 292 subjects had HbA1C <6.5% at blood collection and were classified as incident diabetes. In the undiagnosed diabetes case-control sets, the ORs (95% CIs) across quartiles of hs-CRP were 1.00 (ref), 1.23 (0.59-2.56), 2.26 (1.10-4.66), and 2.46 (1.26-4.83; P for trend=0.009); while in the incident diabetes case-control sets, the ORs (95% CIs) were 1.00 (ref), 1.22 (0.63-2.36), 0.73 (0.38-1.41), and 1.25 (0.65-2.42; P for trend=0.39). Conclusions: In this prospective nested case-control study of Chinese adults, elevated CRP levels are not independently associated with increased risk of incident diabetes. The positive association between CRP and undiagnosed diabetes suggests that CRP may parallel with hyperglycemia. Our results do not support the independent role of CRP in the development of type 2 diabetes in Chinese population.