With the increased sample size of 394,692 European participants here, the association between MAP3K15 and diabetes in the recessive model reached study-wide significance (unspecified/self-reported diabetes: OR = 0.70; 95% CI: [0.62, 0.79], P = 5.0 × 10−9), firmly establishing a protective effect of MAP3K15 loss of function against developing diabetes. Here, MAP3K15 is linked to diabetes mellitus.