This question must be discussed with your OBGYN. Metformin is a pregnancy class B medication. What this means is that there are no human studies that show that it can cause pregnancy problems, but there are also no studies that showed that it will not cause problems. It does mean that there are studies in animals that showed that there are no problems in pregnant animals that were fed the medication. Most physicians will allow pregnant women to continue the medications that are rated class B if they are needed for your overall health. This seems to be the case in you as metformin is probably helping to control your blood sugars. However, often OBGYNs will switch women over to an insulin based regimen that has a class A rating meaning that there are studies in humans that show that this is not harmful to your baby. In the end, it may become a personal choice as insulin based regimens are not desired by some women because of the injections. This is not a question for which you can make a decision without your doctor
. I would suggest that you schedule an appointment with your OB/GYN right away so that the two of you can discuss whether or not to continue the metformin.