late night infomercials only to remember that famous catch phrase, But Wait, There's More! when I stumbled upon a population-based cohort study published in the February 2006 issue of Diabetes Care in which the authors concluded that diabetics treated w/either insulin or sulfonylureas had greater cancer mortality than those treated w/metformin.Thinking along those lines, perhaps I've stayed up too often watching
To arrive at their conclusion, the authors followed for 5+yrs 10,309 diabetics avg 63yo newly prescribed either metformin, sulfonylureas or insulin. Cancer mortality was 5.8% for insulin users, 4.9% for sulfonylurea users and 3.5% for metformin users. But recall & apply Einstein's theory of relativity : we don't know whether insulin & sulfonylureas are more dangerous or whether metformin is protective. All we can conclude is that metformin is better relative to insulin & sulfonylureas when it comes to cancer deaths.
But the good news is that we have the foundation for a trend of benefit from metformin that is less likely to be a fluke given 4 disparate studies. Now all we need is a randomized, double-blinded, placebo-controlled trial of metformin vs cancer risk & outcomes . . .