Illustration showing metformin (blue and grey spheres) binding to an original cation tranporter-1 (OCT-1) membrane receptor (multicoloured helices). Metformins molecular structure is also shown in close up (top left). Metformin is a drug used in the treatment of type 2 diabetes. It reduces hepatic production of glucose, decreases intestinal absorption of glucose, enhances insulin sensitivity, and decreases appetite. The molecular mechanism by which it does this is not fully understood.