Should we reconsider the contra-indications of metformin?

Metformin is the only antidiabetic drug associated with a mortality reduction, but its use is limited by multiple contraindications. In observationnal studies, more than 25% diabetic subjects are treated with met formin despite at least one contra-indication. Lactic acidosis is frequently associated to metformin treatment, but no study demonstrated to date the specific role of met formin in this deleterious process. Data from REACH register indicate a significant decrease in mortality in type 2 diabetic subjects receivin met formin, includiong those with moderate renal failure or cardiac insufficiency. Maintaining metformin in patients with stable cardiac failure or moderate renal insufficiency results in increased risks, but stopping this treatment probably worsens the prognosis. The challenge is to optimize the benefice/risk ratio by stopping metformin in situation of growing risks.