The causes of weight loss in diabetic patients mainly include the following possibilities: First, excessive blood sugar, diabetes patients with elevated blood sugar significantly, a large amount of glucose excreted with urine, the body can only carry out fat decomposition to supply energy, so patients will appear the symptoms of wasting, polyuria, polyhydramnios. Second, the dietary factors, diabetes diet is the basis for the treatment of diabetes, some diabetic patients with too strict dietary control, or diet is too biased also easy to cause weight loss. Third, certain drugs, such as metformin preparations can promote the use of peripheral glucose and promote anaerobic enzymes, some patients taking metformin may experience weight loss. Fifth, combined with other diseases, diabetic patients who are combined with hyperthyroidism, gastrointestinal malignancies and other wasting diseases may also lead to weight loss.