Globulins with molecular mass less than 40 kDa are called microglobulins, and β2-microglobulin (β2-MG) is commonly used in clinical practice. high blood β2-MG value represents a decrease in glomerular filtration rate or an increase in synthesis and secretion in vivo, and a high value of urinary β2-microglobulin represents a decrease in reabsorption in the proximal tubule. β2-microglobulin is often used to look at the situation of diabetic patients with mild renal hypoplasia. High blood β2-MG and normal urine β2-MG: decreased glomerular filtration function (renal failure, acute and chronic nephritis, etc.); normal blood β2-MG and high urine β2-MG: decreased tubular reabsorption function (renal transplantation rejection, Wilson’s disease, etc.); high blood and urine β2-MG: increased synthesis and secretion in vivo or damage to the glomerulus and tubule (diabetic nephropathy, chronic hepatitis, malignant tumors, autoimmune disease, etc.). High blood and urine β2-MG: increased synthesis and secretion in the body or damage to both glomeruli and tubules (diabetic nephropathy, chronic hepatitis, malignant tumors, autoimmune diseases, etc). High microglobulin values should be analyzed in the context of the specific disease.