The exact way metformin works is unclear, but the drug also appears to improve or correct other conditions associated with the metabolic syndrome, such as high fat levels in the blood, the way calcium enters cells, blood clotting abnormalities, and obesity. When compared with conventional diabetes therapy, metformin significantly reduces the risk for heart attack, diabetes-related death, and overall death. Metformin is especially well suited for treatment of obese diabetic persons with normal kidney function. The drug may not be appropriate for thin elderly patients.