Insulin is a very important glucose-lowering hormone in the human body, synthesized and secreted by pancreatic β-cells and released into the blood, acting on muscle, fat, liver and other tissues through the blood circulation, playing an important role in lowering glucose in the body, and maintaining blood glucose in the normal narrow range together with other glucose-raising hormones in the blood. Under physiological conditions, blood insulin levels show a positive regulatory relationship with blood glucose levels, i.e., when blood glucose levels rise, insulin levels will rise, and when blood glucose levels fall, insulin levels will fall. To determine whether there is any abnormality in the blood insulin level, it is necessary to analyze the blood glucose level synchronously. When the measured blood insulin level is low, if the blood glucose level is also low, the insulin level is normal at this time. When the blood insulin level is low, but the blood glucose level is high, it suggests that there is a problem in the synthesis and secretion of insulin level as well as in the process of transit, and further testing is needed to determine the cause of the low blood insulin level according to other laboratory tests.