INS and pachyonychia congenita: Meta-analysis of the 11 observational studies reported no significant association between metformin (OR = 1.04, 95% CI 0.73-1.46) or TZDs (OR = 1.13, 95% CI 0.73-1.75) and PC incidence, while the risk of PC increased by 79% and 185% with sulfonylureas (OR = 1.79, 95% CI 1.29-2.49) and insulin (OR = 2.85, 95% CI 1.75-4.64), respectively.