Dr. Hibberd's answer:
 

Metformin is generally well tolerated if it is started at a low dose and gradually adjusted up over several weeks. It is use for Type 2 (adult onset) diabetes management. It does not replace insulin in those needing insulin, but it may decrease insulin requirements.
 

That said, some patients simply cannot use this medication because of side effects. Often full doses are prescribed too quickly, and intolerance (including nausea, vomiting, renal failure) is common when it is not introduced gradually.
 

Ask your doctor for help here, as this medication has excellent long-term results without the elevated cardiac risks seen with the older hypoglycemic agents used before metformin became available. The main reason I like metformin (if it can be used without intolerance) is that it sensitizes your cells to the insulin you have without elevating insulin levels, and it does not stimulate appetite. In fact, weight loss is quite commonly a welcome side effect of this agent.
 

This agent helps prevent high insulin levels. High insulin levels will increase heart attack risks, yet glucose control is essential for overall body function. There are alternatives to metformin if true intolerance is present, but be sure to consult your physician. Perhaps you take supplements or other conditions that are present can cause problems with metformin.