To evaluate the islet function and insulin secretion pattern of post-pancreatitis diabetes mellitus by oral glucose tolerance testing, and to explore the pathophysiological characteristics of PPDM-C which provide evidence for the diagnosis of PPDM-C.

Blood samples will be collected from patients with chronic pancreatitis by oral glucose tolerance test (steamed bun meal test, SBMT) to assess their pancreatic islet function and insulin secretion pattern, measure other intestinal hormones, exosomes, plasma metabolites, and serum biochemical factors to characterize the pathophysiological features of PPDM-C and provide evidence for the diagnosis of PPDM-C. In order to better understand the glycemic fluctuations in patients with chronic pancreatitis combined with diabetes and guide subsequent treatment, Continuous Glucose Monitoring would be used in patients with chronic pancreatitis who had new-onset diabetes or poor glycemic control.

Inclusion Criteria:

1. Age 15-85
2. patients with the diagnosis of chronic pancreatitis and diabetes mellitus (exclude type 1 diabetes).
3. participants with painless chronic pancreatitis were diagnosed with diabetes within 2 years of the diagnosis of chronic pancreatitis.
4. participants with painful chronic pancreatitis were diagnosed with diabetes after the first attack of chronic pancreatitis.
5. patients with chronic pancreatitis were previously diagnosed type 2 diabetes mellitus for more than 3 years.

Exclusion Criteria:

1. Participants with suspected malignant tumors of the pancreas or other sites of the body (including pancreatic cyst and Benign pancreatic tumor), or participants in the terminal stage of severe disease
2. Prior pancreatic surgery (including total pancreatectomy, pancreaticoduodenectomy, distal pancreatectomy, pancreatojejunostomy, or Frey), and prior bariatric or gastrointestinal surgery.
3. Serious mental illness, lesion of the liver (alanine aminotransferase or aspartate aminotransferase > 3 times the upper reference limit) or kidney (eGFR<60 mL/min/1.73 m2), pregnancy, breastfeeding or planning pregnancy, or accompanied with active liver diseases such as hepatitis B or hepatic cirrhosis.
4. Diagnosed type 1 diabetes, or other metabolic diseases that affect blood glucose
5. Using high-dose insulin preparations, or drugs affecting glucose metabolism (oral steroids, thiazide diuretics, beta-blockers, beta-agonist, nicotinic acid, immunosuppressant agents, antiretroviral drugs, and antipsychotics)
6. Acute complications of diabetes (diabetic ketoacidosis, severe hypoglycemia), severe microvascular disease (proliferative diabetic retinopathy, known diabetic nephropathy or neuropathy requiring treatment), and macrovascular disease (uncontrolled arterial hypertension, uncontrolled coronary artery disease, congestive heart failure, history of cerebrovascular event, seizure disorder, syncope, adrenal insufficiency, neurologic disease or atrial fibrillation) within the 12 months prior to enrollment.
7. Hospitalization for acute pancreatitis within the 2 months prior to enrollment or currently suffering acute inflammation.
8. Have been enrolled or currently participating in other clinical trials within the 3 months prior to enrollment.
9. Patients who refused to participate in the study

Patients with chronic pancreatitis treated in the Department of Gastroenterology of Changhai Hospital