Metformin, heart failure, and lactic acidosis: is metformin absolutely contraindicated?

Abstract
Data sourcesWe searched Medline with the following terms: metformin, phenformin, biguanides, biguanide, lactic acidosis, lactic acid, heart failure, cardiac failure, congestive cardiac failure, left ventricular impairment, metformin contraindications, renal impairment, renal failure, diabetes, type 2 diabetes, non-insulin dependent diabetes, and combinations of these terms. In addition, we consulted the Cochrane systematic reviews.