Answer:
Levels of fasting glucose that are between 100 and 120 mg/dl indicate a risk of diabetes and are what many call "pre-diabetes". This is not the same as diabetes.
Taking a medication such as Metformin (commonly used for diabetes) has not shown any benefit in reducing the risk of actually developing diabetes. What is well established in studies as a way to reverse prediabetes is to work with your medical provider to monitor your glucose levels over time, and work on adjusting diet, losing weight and exercising more.