Pioglitazone hydrochloride in combination with metformin therapy improves glycemic control in the treatment of patients with type 2 diabetes mellitus: a randomised placebo-controlled study. - Einhorn,D.; Rendell,M.; Rosenzweig,J.; Egan,J.W.; Mathisen,A.L.; Schneider,R.L. (Clinical Therapeutics, 2000)