Background

The prevalence of type 2 diabetes (T2D) is increasing rapidly in China, while few prospective studies explored the risk of T2D in Chinese population. The purpose of this study is to examine the impacts of elevated serum ferritin, soluble transferrin receptor levels, and the ratio of soluble transferrin receptor to ferritin on incident T2D in China.

Methods

We used a subsample of 3,198 non-diabetes adults aged 20 years and above who participated in the China Health and Nutrition Survey (CHNS), an ongoing, open-cohort study in 2009 and followed up through 2015. We measured serum ferritin and insulin concentrations with radioimmunoassay, soluble transferrin receptor concentration with nephelometric assay, and hemoglobin A1c (HbA1c) with high-performance liquid chromatography system. We defined T2D as Hemoglobin A1c (HbA1c) ≥ 6.5%, diagnosed with T2D by a physician, or taking anti-T2D medications.Controlled for age, gender, and other potential confounders, we used logistic regression to assess the association between elevated serum ferritin and incident T2D.

Results

Incident rate of T2D was 6.4% during the six-year follow-up. Participants who developed T2D had significantly higher serum ferritin level at baseline (169.4 ng/mL vs 124.6 ng/mL, p<0.01) than their peers. Compared to the first quintile, the relative risk (RR) of the fifth quintile of ferritin level was 2.05 (95% CI 1.16-3.62) (P-trend=0.015). The RR of the second quintile of the soluble transferrin receptor to ferritin was 1.86 (95% CI 1.10-3.15) (P-trend=0.046), compared to the reference group (fifth quintile).

Conclusions

Elevated ferritin levels increased the risk of incident T2D. These findings may have important implications in screening and preventing T2D in Chinese adults.