Is Increased Dosage Of Diabetes Pill Necessary Before Meniscus Repair Surgery?

My mother is preparing for meniscus repair surgery on Wednesday. She is a diabetic with her numbers staying around 195. She was asked by her dr. to increase one of her diabetic pills. Sorry, do not know the name...maybe metforman. Anyway, she's experience a lot of bowel issues and stopped taking the extra pill 24 hours ago. She is telling me her stomach continues to "rumble" as it does when you have the flu or feel you need to use the restroom. She is not running a fever and feels fine otherwise. Do we need to contact her dr. before the surger? She has taken Pepto and Tums....Pepto has helped with any diarrhea, but the stomach is still upset. Any thoughts?