When we see a patient with hypoglycemia, we will first consider that it is caused by glucose-lowering drugs, pre-diabetes, or islet cell tumor, while other conditions are rarely considered by clinicians, or let’s listen to the explanation of the laboratory staff. The patient had no symptoms but was found to be hypoglycemic A 79-year-old female patient had her blood drawn at 7:00 a.m. and sent to the clinical biochemistry department for glucose determination, and the result was 1.91 mmol/L. The result was 1.94 mmol/L after review by the laboratory staff, and there was little change. The test department uses the glucose oxidase peroxidase (GOD-PAP) method to determine blood glucose. The patient was in a state of critical value, so the testing staff reported the blood glucose test results to the clinic, but the clinician’s first reaction was that the test was done incorrectly. The tester then went to the clinic to find out how the specimen was collected, and the nursing staff certified that the specimen was collected without error. The clinical tested again with a rapid blood glucose meter and the result was 5.3 mmol/L. Laboratory tests with blood glucose below 2.8 mmol/L are considered hypoglycemia, and patients often show palpitations, sweating, hunger, weakness, blurred vision, pale face, headache, disorientation, and in severe cases, impaired consciousness or even coma and death. However, at that time, the patient was in a good state, no discomfort, and should not be in a hypoglycemic state. How to explain this situation to clinicians? Many diseases can cause pseudo hypoglycemia At present, GOD-PAP method and hexokinase (HK) method are widely used for laboratory blood glucose determination, among which GOD-PAP method requires glucose oxidase and peroxidase enzyme which are easy to obtain, low cost, accuracy and precision can meet clinical requirements, and is a general laboratory routine method. However, some reducing substances such as uric acid, reduced glutathione (GSH), vitamin C and bilirubin can inhibit the color rendering reaction, which will cause false hypoglycemia. Therefore, the examiner should ask the clinician about the patient’s drug use and whether there is any interference of reducing substances. The most common clinical diseases that cause pseudo-hypoglycemia are chronic granulocytic autoglycemia, followed by true erythrocytosis and acute monocytic leukemia. Patients usually present with pseudo-low venous glucose and normal fingertip glucose. In addition, pseudo-hypoglycemia is also observed in patients with Raynaud’s syndrome and in patients in shock, but due to impaired peripheral circulation, it manifests as a pseudo-lowering of fingertip blood glucose and normal venous blood glucose.