Lack of Metformin Effects on Different Molecular Subtypes of Breast Cancer under Normoglycemic Conditions in vitro

Dysregulation of carbohydrate and fatty acid metabolism is a major public health problem with a growing incidence throughout the world. The total number of peoples with diabetes mellitus is projected to rise from 171 million in 2000 to 366 million in 2030 (Wild et al., 2004). Diabetes is most often associated with obesity. The combination of diabetes and obesity increases breast cancer risk up to 20% (Wolf et al., 2005). Furthermore, diabetic women with breast cancer have worse disease-related clinical outcomes than their nondiabetic counterparts (Lipscombe et al., 2008; Peairs et al., 2011). Metformin is a biguanide oral hypoglycemic agent that has been used for over half a century to treat type 2 diabetes as the first line drug. This drug is currently used by at least 120 million people worldwide (Viollet et al., 2012). Metformin is a safe drug, its most common side