Diarrhea is medically known as “diarrhea”. Diabetic patients with constant diarrhea is a certain risk, may be the adverse reaction of glucose-lowering drugs, infection, improper diet and other reasons, and in serious cases may lead to diabetic emergency, it is recommended that diarrhea as soon as possible to consult a doctor to clarify the cause, as soon as possible treatment. Diabetic patients who have diarrhea, and is persistent diarrhea should be taken seriously, because persistent diarrhea is likely to cause dehydration leading to hypertonic hyperglycemia syndrome. This diabetic emergency is more critical, with many complications and a high mortality rate; therefore, persistent diarrhea is more dangerous for diabetic patients. Glucose-lowering medications such as metformin and glimepiride may lead to gastrointestinal reactions and persistent diarrhea, which may also be caused by viral, bacterial, fungal, or parasitic infections, or by diseases such as acute gastroenteritis. Prompt medical attention should be sought to clarify the cause and treat the symptoms. Therefore, diabetic patients should pay attention to monitoring blood sugar, reasonable and healthy diet to avoid diarrhea. If diarrhea occurs, especially severe diarrhea should be promptly to the hospital for treatment.