Performance of New Biomarkers of Nephropathy in Patients with Type 1 Diabetes Mellitus

Introduction: It is known that laboratorial tests (urinary albumin excretion and glomerular filtration rate), routinely used for nephropathy diagnosis in type 1 diabetes (T1DM), have limitations that justify the evaluation of new renal biomarkers. This study assessed the performance of cystatin C, alkaline phosphatase (AP) and gamma-glutamyl transferase (GGT) for nephropathy diagnosis in T1DM patients. The reduction of economic cost and increase in sensibility and specificity from correct biochemical diagnosis of diabetic nephropathy is an important objective of this work.

Methods: Cystatin C, AP and GGT were determined in plasma and urine of healthy individuals (N=35) and T1DM patients with (N=45) and without nephropathy (N=80).

Results: The plasma levels of cystatin C, AP and GGT, as well as urinary levels of cystatin C and AP were able to differentiate diabetic patients with and without nephropathy. Plasma cystatin C better followed the progression of albuminuria. Cystatin C and AP discriminated the onset of nephropathy in T1DM patients better than creatinine. AP plasma/urine ratio progressively increased from the controls to the diabetic patients without and with nephropathy.

Conclusion: The plasma levels of cystatin C and AP may be useful, with the classical markers of renal function, for nephropathy diagnosis and monitoring in T1DM patients.