Metformin showed higher protective effect of liver cancer when compared with insulin (OR = 0.36; 95% CI, 0.25–0.51), other than sulfonylurea (OR = 0.65; 95% CI, 0.55–0.78) and nonuser of any ADM (OR = 0.62; 95% CI, 0.40–0.98). Here, INS is linked to liver cancer.