In addition, the difference in age ranges of the study participants in T2DM GWAS (35–70 years of age) vs. GDM genetic association studies (substantially younger, reproductive age) might also contribute to the attenuated MTNR1B rs10830963 associated genetic effect sizes reported for T2DM compared to GDM development. Here, MTNR1B is linked to type 2 diabetes mellitus.