INS and type 2 diabetes mellitus: In addition, one study of insulin versus no insulin found a decreased risk of prostate cancer in insulin users, but no difference in risk when analyzing insulin versus other anti‐diabetic drugs;13 another study of insulin versus other glucose‐lowering agents found no difference in risk.12 In contrast, other observational studies found that men on metformin7, 8, 10 and insulin,1, 7, 8, 31versus men not treated with these anti‐diabetic drugs, irrespective of T2DM status, had a decreased risk of prostate cancer.