There are the following causes of high blood glucose in the elderly: 1. The most common cause of high blood glucose in the elderly is diabetes mellitus, which occurs in the elderly mainly as type 2 diabetes mellitus. 2. Secretory diseases outside the pancreas, such as pancreatitis trauma, pancreatectomy, pancreatic tumor, cystic fibrosis of the pancreas, hemochromatosis, fibrous calcific pancreatic disease; 3. Diseases of the endocrine system, including acromegaly, Cushing’s syndrome, pancreatic hyperglycemia, hyperthyroidism, growth hormone tumor, aldosterone tumor, etc.; 4, other system infections: severe infections other than the pancreatic system, such as sepsis, severe pneumonia, etc. can lead to high blood glucose; 5, patients in stressful situations, blood glucose can also be high.