Chronic kidney disease (CKD) is a major trouble in public health worldwide due to its rapid and random prevalence especially in diabetic patients. Further, diabetic nephropathy is a common cause of renal failure occurred in diabetic patients accompanied with low level of albumin in urine at early stage. Notably, early recognition of structural and functional alteration in the kidney is required and essential to identify the appropriate treatment at the beginning of renal syndromes. Several studies exhibit the essential role of serum creatinine in assessment of glomerular filtration rate (GFR) as a biomarker of renal failure. Alternatively, here findings demonstrate that level of serum cystatin-c is an efficacious candidate that can be revealing the possible alternations in renal function including children patients. Thus, blood samples collected from renal and/or diabetic patients showed contradictory relationship between serum cystatin-c level and GFR independent from diabetic syndromes. The results strongly indicate the possible exploiting of serum cystatin-c as an early indicator for renal disease. Collectively, current data further confirm the crucial role of serum cystatin-c in early detection of renal failure via reverse connection with GFR particularly in diabetic children.