Assessment of kidney function in diabetic patients. Is there a role for new biomarkers NGAL, cystatin C and KIM-1?

Assessment of kidney injury early detection in diabetic patients has great importance for therapy and prognosis. The aim of this study was to assess whether neutrophil gelatinase-associated lipocalin (NGAL), cystatin C, and kidney injury molecule-1 (KIM-1) could represent sensitive markers of kidney function/injury in patients with coronary heart disease and diabetes. The study comprised 121 consecutive patients with diabetes referred for coronary angiography due to coronary heart disease and a reference group consisting of 64 patients without diabetes. Cystatin C, serum and urinary NGAL values were significantly higher in diabetics than in non-diabetics. There was no significant difference in KIM-1 levels in both groups. Serum NGAL in diabetic group was associated with serum creatinine, fibrinogen, urinary NGAL, cystatin C and inversely related to kidney function assessed with 4 equations. After analysing levels of studied biomarkers in both groups, no significant difference in patients with estimated glomerular filtration rate (eGFR) below 60 ml/min/1.73m2 was found. The analysis of patients with eGFR over 60 ml/min/1.73m2 showed significant differences in cystatin C and urinary NGAL levels. The area under the curve for serum NGAL, urinary NGAL and cystatin C was 0.60 (95% CI, 0.51 to 0.69), 0.59 (95% CI, 0.5 to 0.68), 0.62 (95% CI, 0.54 to 0.71), respectively, good cut-off values of studied biomarkers to detect diabetes were not found. NGAL, cystatin C and KIM-1 are not more useful than eGFR in the assessment of kidney function in diabetic patients with coronary heart disease.