Diabetes mellitus for more than 30 years, recently always nausea and vomiting, mostly considered to be diabetic ketoacidosis, combined with digestive system diseases, drug side effects, improper diet. 1. Diabetic ketoacidosis: a common acute complication of diabetes is ketoacidosis, which can cause nausea and vomiting, and requires prompt treatment, and if the condition further worsens, it may be life-threatening. 2. Combined digestive system diseases: If diabetic patients have acute gastroenteritis, they will also have nausea and vomiting symptoms. 3. Metformin: Metformin is the first-line drug for diabetes, and nausea and vomiting may occur when taking Metformin. 4. Improper diet: Diabetes itself is a chronic disease that is difficult to control and treat effectively. If patients do not pay attention to their diet in their daily life, often consume spicy or stimulating foods or overeat, it will increase the burden on the digestive system, which will lead to gastrointestinal damage and induce the symptoms of nausea and vomiting. Diabetic patients with recent symptoms of nausea and vomiting should go to the local hospital in time to identify the problem and treat it as soon as possible.