I would be surprised if a modest reduction in Metformin had this effect, though it is said to reduce the amount of sugars produced by your liver, so the Dawn Phenomena (rising blood sugars first thing, before food) might be the first to go up. I would look at other things in your life. Are you fighting a cold or other infection? What are you having for dinner or late night snacks? Have you been sleeping badly or getting up earlier or later? Tell us what you normally eat, food choices are, so often, behind rises in blood sugars.
Sally