OPN1LW and type 2 diabetes mellitus: Top compounds from the anti-diabetics class include metformin (P = 4.30 × 10−14), which is the most commonly prescribed drug for type II diabetes and affects 14 of the 47 ROP genes, and thiazolidinediones such as troglitazone (P = 4.94 × 10−10), rosiglitazone (P = 7.58 × 10−10) and pioglitazone (P = 3.75 × 10−9) which activate peroxisome proliferator-activated receptors (PPAR) for various effects and affect 17, 18, and 8 of the ROP genes, respectively.