About 80% of patients with pancreatic adenocarcinoma have aberrant fasting blood glucose at the time of diagnosis. The consistent association between pancreatic cancer and diabetes mellitus has long been recognized and even been termed as "chicken and egg". Many reports have found that pancreatic cancer can result in diabetes, which is called type 3c diabetes. New-onset diabetes is commonly observed in pancreatic cancer patients and has been considered as a potential screening sign. Moreover, diabetes has been found as a predictor of poor outcome in pancreatic cancer.

Pancreatic cancer cells have a strong dependence on glucose and they are well-known for their sweet teeth. High glucose is associated with impaired immunologic reaction, intolerability to chemotherapy, radiotherapy and other major treatments, an increased risk of pancreatic surgery. Given the linkage between pancreatic cancer and diabetes or high blood glucose, a clinical trial is needed to validate the effect of metformin and insulin on regulating blood glucose in type 3c diabetes.

Inclusion Criteria:

• Signed informed content obtained prior to treatment
• Age ≥ 18 years and ≤ 80 years
• Eastern Cooperative Oncology Group (ECOG) performance status 0-2
• Patients must have histologically confirmed pancreatic adenocarcinoma
• History of diabetes mellitus, or newly diagnosed diabetes mellitus according to the American Diabetes Association criteria
• The expected survival after surgery ≥ 3 months

Exclusion Criteria:

• Active second primary malignancy or history of second primary malignancy
• Patients who have received any form of anti-tumor therapy including surgery, chemotherapy, radiotherapy, interventional chemoembolization, radiofrequency ablation, and molecular targeted therapy
• Inflammation of the digestive tract, including pancreatitis, cholecystitis, cholangitis, etc
• Pregnant or nursing women
• Patients who are unwilling or unable to comply with study procedures