If you experience dizziness and nausea after taking metformin, you should stop taking it if it is serious and switch to other kinds of glucose-lowering drugs or apply insulin for glucose-lowering treatment. The main and most common side effect of metformin is gastrointestinal reactions, including nausea, vomiting, diarrhea, etc. Some people can tolerate it after a few days, but some patients have more severe reactions and can not tolerate it, this situation should be stopped, it is recommended to choose to take it with or after meals, starting with a small dose and gradually increasing the dosage, which can effectively reduce the adverse reactions of the digestive tract. Metformin can be applied alone or in combination with other hypoglycemic drugs or insulin, and is suitable for obese patients with type 2 diabetes, with the effect of reducing insulin resistance and increasing insulin sensitivity, but long-term use may lead to vitamin B12 deficiency, to regularly monitor the level of vitamin B12, if necessary, timely supplementation.