A normal person in a fasting state has a venous plasma glucose level of 3.9-6.1 mmol/L. In a situation where the body does not eat overnight, it still maintains normal blood glucose so that we do not become hypoglycemic. Plasma glucose<2.8 mmol/L is considered hypoglycemia. Absolute or relative excess insulin levels from any cause, or liver disease resulting in reduced hepatic glycogen reserves and reduced hepatic glucose xenobiogenesis, can lead to low fasting blood glucose.
Some diseases may cause excessive insulin secretion, such as various tumors of the pancreas, multiple endocrine adenomatosis, or overuse of glucose-lowering medications. In addition, some diseases can cause a decrease in the secretion of other hormones, resulting in a relative overproduction of insulin: hyperalgesia, hypopituitarism, hypothyroidism, and glucagon deficiency due to islet alpha cell injury. Liver diseases are common in severe hepatitis, cirrhosis, hepatocellular carcinoma, and serious liver diseases such as hepatic necrosis. It is recommended to first clarify whether it is true hypoglycemia, and secondly to further investigate the cause.