INS and diabetes mellitus: T1DM, Type 1 diabetes mellitus; T2DM, Type 2 diabetes mellitus; GDM, Gestational diabetes mellitus; FI, Fasting insulin; FG, Fasting glucose; HbA1c, Hemoglobin A1c; MR-PRESSO, Mendelian randomization pleiotropy residual sum and outlier; Q value, the statistics of Cochran’s Q test.