Genotype-specific association of dietary chromium intake with type 2 diabetes according to FTO rs9939609: a case–control study

Type 2 diabetes mellitus (T2DM) is a major global health issue, with rising prevalence and costly complications. Genetic variations may influence the association between dietary exposures and T2DM risk. Dietary intake of chromium may be associated with glycemic control. This study examined the relationship between dietary chromium intake and T2DM across different FTO rs9939609 genotypes. A total of 400 women, including 200 women with T2DM and 200 healthy women, were initially recruited. After applying the exclusion criteria, 353 participants (179 women with T2DM and 174 healthy controls) were included in the final analysis. Dietary chromium intake was evaluated using a comprehensive food frequency questionnaire (FFQ) and Nutritionist IV software. The FTO rs9939609 polymorphism was genotyped using the Tetra-ARMS PCR method. Dietary chromium intake was higher among controls than cases in women with the TT genotype (0.75 vs. 0.045 mg/d, p = 0.021). Among women with the TT genotype, higher dietary chromium intake was significantly associated with lower odds of T2DM in all adjusted models (OR = 0.984, 95% CI: 0.972–0.996; p = 0.010). No significant association was observed among women carrying the AA/AT genotypes. Higher dietary chromium intake was associated with a lower risk of T2DM among women carrying the TT genotype of FTO rs9939609. These findings suggest a genotype-specific association between dietary chromium intake and T2DM risk and highlight the potential relevance of genetic background in dietary approaches to T2DM prevention.