Evaluation of serum cystatin C level as an early biomarker of nephropathy in children with type 1 diabetes mellitus attending Suez Canal University Hospital

Background Diabetic nephropathy is a syndrome characterized by a secondary renal disease in patients with diabetes mellitus (DM). It is a serious complication of DM and is the most common cause of the end-stage renal disease. Aim To evaluate the diagnostic value of serum cystatin C level as an early biomarker of nephropathy in children with type 1 diabetes mellitus (T1DM) attending Suez Canal University Hospital. Patients and methods This was a descriptive cross-sectional study that included 49 children with T1DM attending the pediatric endocrinology outpatient clinic of at Suez Canal University Hospital, Ismailia, Egypt, and 49 matched healthy controls during the period from 1/12/2020 to 1/3/2021. The target population was children with T1DM aged between 6 and 18 years of both sexes who were attending the pediatric endocrinology outpatient clinic of Suez Canal University Hospital, Ismailia, Egypt. All studied patients and healthy controls were subjected to history taking and general and systemic examination. The following investigations were done: fasting blood sugar, serum creatinine, estimated glomerular filtration rate, albumin/creatinine ratio (ACR), urine analysis, hemoglobin A1C, and serum cystatin C level). Results ACR and cystatin C levels were significantly higher in albuminuric than nonalbuminuric diabetic patients. There was a significant positive correlation between serum cystatin C and duration of diabetes, hemoglobin A1C, and ACR. For serum cystatin C, regarding detection of microalbuminuria, the sensitivity was 66.7%, specificity was 75%, the positive predictive value was 49%, and the negative predictive value was 0.52%, with the best cut-off value of 0.98 (mg/l). Conclusion Microalbuminuric diabetic patients showed an increased serum cystatin C levels, whereas their creatinine levels were still within normal. Serum cystatin C levels well reflect the severity of renal damage caused by DM. The serum cystatin C measurement might become a useful, practical, noninvasive, and accurate tool for early detection of microalbuminuria and renal insufficiency in T1DM.