Pancreatic cancer may cause patients to have elevated blood sugar. Since pancreatic cancer affects the islet cells of the pancreas, it may lead to a decrease in insulin secretion and a rise in blood sugar. Pancreatic cancer usually refers to a tumor in the pancreas, which is a malignant tumor. If the cancer occurs in the head of the pancreas, it usually causes less elevation of blood glucose. If it occurs in the tail of the pancreas, it is more common to have elevated blood glucose. Because the number of islet cells in the middle of the pancreas is very high, a tumor in the tail of the pancreas will damage or even affect the insulin cells, and the pancreas itself will secrete less insulin, and blood sugar will naturally rise.