Metformin is the oral drug of choice for type 2 diabetics who do not respond well to diet and lifestyle changes alone unless contraindicated due to kidney problems. It has a long safety record. Scientific research has proven that metformin is just as good or even better at controlling blood sugar levels than other oral antidiabetic drugs and it causes less weight gain, less low blood sugar, and less cardiovascular events. 

Metformin is sold under the brand names Glucophage, Glucophage XR, Riomet, Fortamet and is also found in other combination diabetes medications. Metformin comes in the immediate release and extended release formulations. The immediate release formulation releases the medication all at once while the extended release formulations release medication over time. The extended release formulation has fewer gastrointestinal (GI) side effects, increases adherence to medications due to its once daily dosing, and has proven to be safer, more effective, and better tolerated than the Immediate release formulation.

Some of the side effects to expect from metformin include:

• diarrhea
• nausea
• vomiting
• abdominal pain
• the passing of gas
• loss of appetite 

Some patients may experience other side effects such as:

• change in taste sensation
• weight loss
• indigestion
• heartburn
• stomach upset
• abnormal stool
• headache
• rhinitis
• infection
• discoloration of the nails
• hives (rash)
• itching
• plaques (scalp, elbows, and knees)
• low blood sugar (hypoglycemia)

Serious side effects may occur in some patients under certain circumstances. These serious side effects are rare and include: 

• chest pain
• lactic acidosis
• vitamin B12 deficiency
• hepatitis 

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