The present results derived from a sample of just under half-a-million participants suggest that the oxytocin system has pleiotropic effects on both social and metabolic phenotypes [16] by providing evidence for the involvement of the oxytocin-signaling pathway in the shared genetic liability of schizophrenia, bipolar disorder, T2D, and several phenotypes linked with CVD and T2D risk. This evidence concerns the gene OXT and type 2 diabetes mellitus.