INS and type 2 diabetes mellitus: When the other neuropsychiatric disorders were also considered, negative genetic covariance was found between BD and T2DM, BD and MetS, SCZ and MetS through the PID insulin signalling pathway (p ≤ 2 × 10−5), as well as between AN and T2DM through the Biocarta insulin pathway (p = 1.26 × 10−5).