Growth arrest-specific protein 6 (Gas6) as a noninvasive biomarker for early detection of diabetic nephropathy

Background: To investigate the diagnostic level of cystatin C and growth arrest-specific gene 6 (Gas6) levels in elderly type 2 diabetic patients with different degrees of diabetic nephropathy (DN). Methods: Four hundred and eighty-two old people, including 130 healthy controls, 130 normoalbuminuric diabetic patients, 122 with microalbuminuria, and 100 with macroalbuminuria, were recruited. Plasma Gas6 and serum cystatin C levels were measured. Results: Plasma Gas6 concentration was significantly lower in diabetic patients with microalbuminuria or macroalbuminuria, as compared with diabetic subjects with normoalbuminuria; while cystatin C was significantly higher. Gas6 was inversely correlated with BMI, WHR, and HbA1c, while cystatin C was inversely correlated with urea nitrogen and creatinine. Multivariate logistic regression analysis showed that, after adjusted for established diabetes risk factors, higher plasma Gas6 was significantly associated with a decreased risk of DN, while higher serum cystatin C was significantly associated with an increased risk. Receiver operating characteristic curve analysis showed that Gas6 was better than cystatin C as a biomarker for early diagnosis and detection of DN, with a cutoff value of 9.435 ng/mL (86.1% sensitivity and 84.6% specificity). Conclusion: Compared to cystatin C, Gas6 may be potentially a better noninvasive diagnostic biomarker for early detection of DN.