Elevated cystatin C is usually indicative of possible kidney disease. It can be seen in renal insufficiency due to various diseases, such as diabetic nephropathy and renal tubular dysfunction. Serum cystatin C ranges from 0.6 to 2.5 mg/L in adults. The original urinary cystatin C in the proximal tubule is almost completely taken up and decomposed by the epithelial cells and does not return to the blood, and only a trace amount is discharged in the urine, therefore, the serum cystatin C level is a sensitive and specific indicator to reflect the glomerular filtration function. When diabetic nephropathy and other causes of renal insufficiency, glomerular filtration rate decreases, then the concentration of cystatin C in the blood increases; if the glomerular filtration rate is normal, and tubular dysfunction will also hinder the reabsorption of cystatin C, then the concentration of cystatin C in the urine rises significantly. Therefore, if cystatin C is high, it usually indicates the presence of renal disease. If the patient finds that the cystatin C is elevated, it is recommended to go to a regular hospital in time, complete the examination to clarify the cause of the disease, and then give targeted treatment or therapy under the guidance of the doctor.