Type 2 diabetes is causally associated with depression: a Mendelian randomization analysis

type 2 diabetes (t2d) has been associated with a high prevalence of depression.we aimed to determine the causal relation by performing a mendelian randomization (mr) study using 34 t2d risk genetic variants validated in east asians as the instrumental variable (iv). an mr analysis was performed involving 11 506 participants from a large longitudinal study. the t2d genetic risk score (grs) was built using the 34 typical t2d common variants. we used t2d_grs as the iv estimator and performed inverse-variance weighted (ivw) and egger mr analysis. the t2d_grs was found to be associated with depression with an or of 1.21 (95% ci: 1.07–1.37) after adjustments for age, sex, body mass index, current smoking and drinking, physical activity, education, and marital status. using t2d_grs as the iv, we similarly found a causal relationship between genetically determined t2d and depression (or: 1.84, 95% ci: 1.25–2.70). though we found no association between the combined effect of the genetic ivs for t2d and depression with eggermr(or: 0.95, 95%ci: 0.42–2.14), we found an association for t2d and depression with ivw (or: 1.75, 95% ci: 1.31–2.46) after excluding pleiotropic snps. overall, the mr analyses provide evidence inferring a potential causal relationship between t2d and depression.