Diagnostic Performance of Cystatin C in the Early Detection of Diabetic Kidney Disease at the University of Nigeria Teaching Hospital, Ituku-Ozalla.

Introduction: There is an increase in the prevalence of diabetes mellitus (DM) globally. Individuals with diabetes mellitus are at higher risk of impairment of kidney function. This study evaluated the diagnostic performance of Cystatin C in the early detection of diabetic kidney disease (DKD).

Methods: Across a sectional analytical study of 300 participants (200 study group and 100 control group). A relevant clinical history was obtained, and a physical examination was carried out. Venous blood was collected to assay for serum creatinine, serum albumin, serum cystatin C, serum urea, fasting blood glucose, and urine for the quantification of urine albumin excretion rate.

Results: The median age of the study group versus the control group was 62.50 for DM with proteinuria, 60.00 for DM without proteinuria, and 60.00 years for the control group (F = 3.524, p = 0.172). The laboratory parameters that were higher in the study group compared to the control group were FBG (141.0, 130, vs. 104 mg/dl, F = 68.456, p = <0.001), serum creatinine (109.0, 88.5, vs. 105.0 umol/l, F = 35.50, p = <0.001), serum cystatin C (1.24, 1.11, vs. 0.84 mg/L, F = 59.27, p = <0.001), and urine albumin excretion (230.0, 102.0, vs. 30.0 mg, F = 128.62, p = <0.001). The diagnostic performance of cystatin C using MDRD and cystatin C eGFR <60ml/min/1.73m2 was 13% and 23%, respectively, for the study group without proteinuria. Also, when the diagnostic efficiency of the variables was compared using ROC, the AUC of creatinine eGFR (MDRD) was less than that of cystatin C eGFR between the cut-off levels of 30 mg and 300 mg of urine albumin excretion. Cystatin C eGFR had a strong negative correlation with urine albumin excretion when compared to creatinine eGFR (MDRD).

Conclusion: This study showed the diagnostic performance of serum cystatin C in the early detection of DKD and that cystatin C-derived eGFR is more sensitive than serum creatinine-derived eGFR in detecting DKD early in people with DM.