Association between serum ferritin, hemoglobin, iron intake, and diabetes in adults in Jiangsu, China

OBJECTIVE - To investigate the association between iron status, iron intake, and diabetes among Chinese adults. RESEARCH DESIGN AND METHODS - This cross-sectional household survey was carried out in 2002 in Jiangsu Province, China. The sample contained 2,849 men and women aged ≥20 years with a response rate of 89.0%. Iron intake was assessed by food weighing plus consecutive individual 3-day food records. Fasting plasma glucose (FPG), serum ferritin, and hemoglobin were measured. RESULTS - The prevalence of anemia was 18.3% in men and 31.5% in women. Mean hemoglobin and serum ferritin increased across groups with increasing FPG. The prevalence of anemia among women was 15.0% in individuals with FPG >7.0 mmol/l compared with 32.6% in individuals with FPG <5.6 mmol/l. There was a similar, however not significant, trend among men. In women, after adjusting for known risk factors, the odds ratio (OR) of diabetes was 2.15 (95% CI 1.03- 4.51) for subjects in the upper quartile of hemoglobin compared with the rest, and the corresponding OR for the upper quartile of serum ferritin was 3.79 (1.72- 8.36). Iron intake was positively associated with diabetes in women; fourth quartile intake of iron yielded an OR of 5.53 (1.47-20.44) compared with the first quartile in the multivariate analyses. In men, similar trends were suggested, although they were not statistically significant. CONCLUSIONS - Iron status and iron intake was independently associated with risk of diabetes in Chinese women but not in men.