Diabetic patients must pay attention to the combination of pancreatic cancer in the process of diagnosis and treatment. The incidence of pancreatic cancer in diabetic patients is significantly higher than in the general population, and the incidence of abnormal glucose tolerance in pancreatic cancer patients is as high as 80% and the incidence of diabetes is 30% to 40%. In a study, 1659 patients with type 1 diabetes and 1499 patients with type 2 diabetes were followed up and the results showed that type 2 diabetes may be the first symptom of pancreatic cancer. Diabetes mellitus and pancreatic cancer can be both separate diseases and two diseases closely related to each other. Due to the high frequency of coexistence of diabetes and pancreatic cancer, it is important for doctors and diabetic patients to prevent pancreatic cancer from being underdiagnosed during the diagnosis of diabetes. Pancreatic cancer is the 4th most common tumor in the digestive system, and the survival rate is only 13.4% one year after diagnosis. Therefore, how to detect it early and treat it early is very important to improve the prognosis. Patients with pancreatic cancer may not have any clinical manifestations in the early stage, or only show some non-specific signs and symptoms of digestive system or endocrine system. When the symptoms of upper abdominal pain are seen within 1 month after the onset of symptoms, there is a 27% chance that the cancer is stage 1 pancreatic cancer; if typical manifestations such as jaundice and wasting occur, the patient has almost always lost the chance of surgical resection. Many patients with pancreatic cancer have elevated blood sugar earlier than symptoms such as abdominal pain. A domestic clinical study reported that about 17% of pancreatic cancer patients may exhibit abnormal glucose metabolism about 2 years before the discovery of tumor lesions, and their clinical features are mainly manifested as type 2 diabetes, but few have positive family history of diabetes, and there are no obesity and other factors that predispose to diabetes, etc. The analysis of 147 cases of pancreatic cancer patients by Ji Shangwei of China-Japan Friendship Hospital of Jilin University found that the incidence of pancreatic cancer among diabetic patients increased significantly, and type 2 diabetes may be the first symptom of pancreatic cancer, and the risk of pancreatic cancer increases with the increase of the duration of diabetes in patients with 2 years of disease. Therefore, clinical diagnosis of the etiology of hyperglycemia must be cautious and should not be satisfied with the diagnosis of type 1 or type 2 diabetes alone. The pathogenesis of pancreatic cancer-associated diabetes is similar to that of type 2 diabetes, i.e., with hyperinsulinemia and insulin resistance. However, compared with type 2 diabetes, the characteristics of pancreatic cancer-related diabetes are: (1) the age of onset is relatively older than 60 years old, and women are more common; (2) there is basically no family history of diabetes; (3) there are no “three more” symptoms, but weight loss is more obvious in a short period of time; (4) there is often abdominal pain or abdominal discomfort at the beginning of the disease; (5) the combination of hypertension and coronary heart disease, especially hyperlipidemia is relatively rare. (5) Combination of hypertension and coronary heart disease, especially hyperlipidemia is relatively rare; (6) Tumor markers CA19-9 and CEA are often abnormal. In conclusion, clinically, middle-aged and elderly type 2 diabetic patients with symptoms such as epigastric pain, low back pain and anorexia should routinely undergo ultrasound examination of the pancreas and be followed up closely; those whose symptoms are not relieved after glycemic control or whose condition has recently worsened, those who respond poorly to oral medication, and those with abnormal laboratory indicators such as islet cell antibodies, insulin antibodies, CA19-9 and CEA should be highly suspected of pancreatic cancer-related diabetes. For such diabetic patients, further imaging examinations such as abdominal CT, MRI, PET, and transendoscopic cholangiopancreatography must be done to confirm the diagnosis of pancreatic cancer as early as possible and improve the survival rate of patients.