Patients with hypoglycemia are first considered to be caused by glucose-lowering drugs, pre-diabetes, and islet cell tumor, while other conditions are rarely considered by clinicians. The following are some explanations from the perspective of professional laboratory personnel. A 79-year-old female patient had her blood drawn at 7:00 am and sent to the clinical biochemistry room for glucose measurement. The result was 1.91 mmol/L, and the result was 1.94 mmol/L after review by the laboratory staff, with little change. The glucose oxidase peroxidase (GOD-PAP) method is used in the laboratory to determine blood glucose. The patient was in a state of critical value, so the laboratory 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 5.3mmol/L. Laboratory examination of blood glucose below 2.8mmol/L is 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 presentation reaction, which will cause false hypoglycemia. Therefore, the examiner should ask the clinician about the patient’s medication 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 can be 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. Timely detection of finger blood glucose can be identified The pseudo-hypoglycemia in this case was manifested by pseudo-lowering of venous blood glucose and normal fingertip blood glucose. The possible cause of the lower blood glucose measurement is the abnormally high M protein in the blood. Haibach et al. reported a case of Waldenstrom’s macroglobulinemia combined with pseudohypoglycemia in which the decrease in blood glucose was actually caused by the high viscosity of the patient’s blood and the sampling error of the autoanalyzer. In a patient with B-cell lymphoma reported by Wenk et al. in 2005, the patient had abnormal M protein bands in serum electrophoresis. The investigators found that falsely reduced venous blood glucose concentrations measured using the hexokinase method and normal venous blood glucose measured using the glucose oxidase method and normal fingertip rapid blood glucose measured using the glucose dehydrogenase method could be due to interference from large amounts of protein precipitation or direct effects of active monoclonal antibodies on the assay. The possible mechanism for the reduced fingertip glucose and normal venous glucose is that the M protein is causing increased blood viscosity or that the high concentration of monoclonal protein is affecting the volume of specimen collected when the volume of blood collected is already low. Again, M protein is increased, but its effect can appear differently for different blood collection methods, different measurement methods and instruments. False reductions in both fingertip and venous blood glucose are possible. When a patient’s hypoglycemia is found to be inconsistent with clinical symptoms and the presence of pseudo-hypoglycemia is suspected, the examiner needs to use different blood collection methods and measurement methods for review. Drugs that interfere with blood glucose measurement should be discontinued for a period of time before measuring blood glucose levels, and both glucose oxidase and glucokinase methods should be used to measure blood glucose. Timely testing of fasting finger blood glucose is also a simple and easy identification method.