U-shape association between white blood cell count and the risk of diabetes in young Chinese adults

Background Chronic low-grade inflammation is related to diabetes risk in population studies. Elevated levels of white blood cells (WBC) were related to the risk of diabetes in cross-sectional studies in the Chinese population. The objective of the study is to assess the prospective association between WBC and the risk of diabetes in the Chinese population. Methods We examined 7445 manual workers aged 18-59 years free from diabetes at baseline. Fasting glucose concentrations and white cell count were measured at annual health examinations from 1997 to 2007. Anthropometric measurements were taken by health workers. In the present study, each participant had at least two measurements of fasting blood glucose. Results During a mean of 4.94 years follow-up, 178 participants developed diabetes. After controlling for known risk factors for diabetes (age, gender, smoking, drinking, parental history of diabetes, body mass index, systolic blood pressure, hepatitis B surface antigen and liver function), a U-shaped association between WBC count and diabetes was found. The hazard ratios (HR) of diabetes across quartiles of WBC count were 1.87 (95% CI 1.15-3.05), 1.00, 1.46 (0.88-2.42) and 2.04 (1.28-3.25). The association was stronger among non-smokers: compared with the second quartile, the HR of diabetes for the first and fourth quartiles of WBC were 3.00 (1.28-7.03) and 3.16 (1.33-7.53). Adjusting for hepatitis B virus infection and liver function did not change the association. Conclusion Both low and high levels of WBC count were associated with an increased risk of diabetes in young workers.