BackgroundThis study investigated the effect of sex and age at type 2 diabetes (T2D) diagnosis on the influence of T2D-related genes, parental history of T2D, and obesity on T2D development.MethodsIn this case–control study, 1012 T2D cases and 1008 healthy subjects were selected from the Diabetes in Mexico Study database. Participants were stratified by sex and age at T2D diagnosis (early, ≤ 45 years; late, ≥ 46 years). Sixty-nine T2D-associated single nucleotide polymorphisms were explored and the percentage contribution (R2) of T2D-related genes, parental history of T2D, and obesity (body mass index [BMI] and waist–hip ratio [WHR]) on T2D development was calculated using univariate and multivariate logistic regression models.ResultsT2D-related genes influenced T2D development most in males who were diagnosed early (R2= 23.5%; females,R2= 13.5%; males and females diagnosed late,R2= 11.9% andR2= 7.3%, respectively). With an early diagnosis, insulin production-related genes were more influential in males (76.0% ofR2) while peripheral insulin resistance-associated genes were more influential in females (52.3% ofR2). With a late diagnosis, insulin production-related genes from chromosome region 11p15.5 notably influenced males while peripheral insulin resistance and genes associated with inflammation and other processes notably influenced females. Influence of parental history was higher among those diagnosed early (males, 19.9%; females, 17.5%) versus late (males, 6.4%; females, 5,3%). Unilateral maternal T2D history was more influential than paternal T2D history. BMI influenced T2D development for all, while WHR exclusively influenced males.ConclusionsThe influence of T2D-related genes, maternal T2D history, and fat distribution on T2D development was greater in males than females.Supplementary InformationThe online version contains supplementary material available at 10.1186/s13293-023-00521-y.