In addition to diet and exercise, the prescription drug Metformin has been proven to increase insulin sensitivity in people with mild to moderate hyperglycemia. Metformin is now the most commonly prescribed oral antidiabetic drug worldwide. It works by increasing insulin sensitivity in the liver (Joshi 2005). It also has a number of other beneficial effects, including weight loss, reduced cholesterol-triglyceride levels, and improved endothelial function.

Metformin is better tolerated than many other antidiabetic prescription drugs, but people with congestive heart failure, kidney or liver disease are not candidates for metformin therapy. Neither are people who consume alcohol in excess. A benchmark assessment of kidney function, followed by an annual renal evaluation, is essential. Vitamin B12 levels should also be checked regularly because chronic use of metformin can cause a folic acid and B12 deficiency, resulting in neurological impairment and disruption in homocysteine clearance.

Metformin is effective on its own. Metformin do not or very seldom causes hypoglycemia. It is being used as an adjunct to control body weight or reduce body weight even though in non-diabetic. Less after meal glucose surge leads to reduction in insulin production. Since insulin promote fat synthesis, indirectly it helps in reducing body weight especially in early stage together with calorie restriction diet. The other beneficial effect of metformin is one do not feel hungry even though they miss meal.