Metformin has been known to cause diarrhea. Especially when first starting it. As others have said. Diet and exercise can help decrease your dependence on oral hyperglycemics. If you take your meds just make sure you eat! They are like any other medication, they all have side effects. It just depends on which one you can live with. I’d try the keto or carnivore diet to help with your blood sugar, obviously at the direction of your doctor but that will definitely decrease your carb consumption which is where a lot of fluctuation in your blood sugar comes from.