Dr Craig Currie of Cardiff University School of Medicine presented findings on metformin at the European Association for the Study of Diabetes (EASD) meeting in Vienna this week.
His research showed that metformin has a protective effect against cancer in people with type-2 diabetes, but that insulin may increase cancer risk in a dose-dependent fashion.
He suggested that metformin could have a role in cancer prevention in people with out diabetes. People with type-2 diabetes on high insulin doses may benefit from screening and combination therapy with metformin, he added.
Dr Jeffrey Johnson of the University of Alberta, Canada, also presented data on cancer risk in people with type-2 diabetes at EASD. His research showed that the relationship between obesity, type-2 diabetes and cancer appears to be associated with insulin resistance and hyperinsulinemia.
He said that epidemiological evidence suggested that glitazones may improve cancer outcomes in patients with type-2 diabetes. He added that ongoing studies were evaluating the use of glitazones as adjuvant therapy in including lung, head, neck and pancreatic cancer.