Elevated serum complement C3 levels are related to the development of prediabetes in an adult population: the Tianjin Chronic Low-Grade Systematic Inflammation and Health Cohort Study.

Aims To investigate whether serum complement C3 is related to the prevalence and incidence of prediabetes in an adult population. Methods A cross-sectional ( n = 10 206) and prospective cohort study ( n = 3333), with a mean (range; 95% CI) follow-up of 2.63 (1-6; 2.58-2.68) years, was conducted in people recruited from the Health Management Centre of Tianjin Medical University General Hospital in Tianjin, China. Measurement of serum C3 concentration, blood fasting glucose, oral glucose tolerance, HbA_1c and other potential confounding factors was performed at baseline and each year during the follow-up. Prediabetes was defined according to the criteria of the American Diabetes Association. Adjusted logistic and Cox proportional hazards regression models were used to assess the relationships between C3 quintiles and prediabetes. Results The prevalence and incidence of prediabetes were 38.5% and 119 per 1000 person-years, respectively. In cross-sectional analysis, after adjustment for potential confounders, the odds ratios of prediabetes for increasing quintiles of C3 were 1.00 (reference), 1.32 (95% CI 1.14-1.53), 1.37 (95% CI 1.18-1.59), 1.75 (95% CI 1.51-2.03), 2.25 (95% CI 1.93-2.62; P for trend < 0.0001). In the cohort analysis, the multiple-adjusted hazard ratio of prediabetes in the highest quintile of baseline C3 was 1.43 (95% CI 1.15, 1.78; P for trend < 0.001), when compared with the lowest quintile. Conclusions These findings indicate that elevated serum C3 levels are significantly related to an increased risk of developing prediabetes in an adult population, suggesting that C3 can be used as a biomarker in high-risk individuals to improve primary prevention of prediabetes and diabetes. [ABSTRACT FROM AUTHOR]