MTHFS and type 2 diabetes mellitus: We identified that COX19, GATM, DCXR, SPATA20, HADHA, SFXN5, STYXL1, SLC25A13, MTHFS, and MCL1 have a causal association with an increased risk of T2DM, while inverse causal effects were found in MRPL32 and ACADVL.