Aims: Iron overload identified by elevated ferritin concentrations has been implicated in risks of altered glucose metabolism and diabetic complications. The relationship between ferritin and insulin resistance in different gender and ethnicities remains uncertain; this study aimed to investigate it using homeostasis model assessment (HOMA-IR), and to explore whether it is gender-specific. Methods: A total of 524 type 2 diabetic patients were selected cross-sectionally from a cohort participating in a diabetic control study in Taiwan. Result: Overall, tertiles of ferritin were significantly and dose-dependently associated with elevated fasting plasma glucose, hemoglobin A1c, high-sensitivity C-reactive protein, HOMA-IR levels as well as Western dietary pattern scores generated by factor analysis (all p trend <0.05). Stratified by gender, a 1-tertile ferritin increase significantly correlated with a 0.241-unit increase in HOMA-IR (beta = 0.241, p = 0.001) in female diabetes, but not in male diabetes (beta = 0.072, p = 0.232), after adjusting for demographic, dietary, clinical and inflammatory factors. Conclusion: Iron overload, which produces elevated levels of ferritin, may augment insulin resistance in female but not in male type 2 diabetes. Longitudinal studies are warranted to establish relationships between iron stores and diabetes development in men and women of different ethnicities.