Basically Metformin will reduce the production of glucose from your liver via glycogenolysis. Therefore it will not worsen your insulin resistance like insulin injection. There is also a EX version as long release which can be taken once a day. As long as your pancreas is still in shape its consider to be the first line medication for new diagnosis or pre-diabetes. However if your pancreas was deteriorated Metformin may not help much. Follow your doctor advice and in a long run you may consider follow a reduce carb diet to let your insulin resistance recover.