Serum osteoinductive factor is associated with microalbuminuria and diabetic nephropathy in type 2 diabetes

We investigated the relationship between serum osteoinductive factor (OIF) and diabetic nephropathy (DN), and its potential use as a diagnostic marker for DN. This study included 177 patients with type 2 diabetes mellitus (T2DM) with normoalbuminuria, 42 with DN and microalbuminuria, and 49 with DN and macroalbuminuria, as well as 296 controls. Baseline characteristics, microalbuminuria prevalence, macroalbuminuria prevalence, and diabetic complications were compared between OIF quartiles. Serum OIF was examined by enzyme-linked immunosorbent assay. Other clinical parameters were measured using standard methods. Correlations between OIF and clinical parameters were assessed using Pearson correlation. Predictive value of OIF for DN was assessed using multivariate logistic regression. Receiver operator characteristic (ROC) curves were used to identify the optimal sensitivity for serum OIF. Univariate analysis showed microalbuminuria prevalence negatively correlated with OIF, 4.3% for quartile 1 (Q1) (>367.5pg/mL), 13.7% for Q2 (320.3-367.5pg/mL), 17.9% for Q3 (275.0-320.3pg/mL), and 28.8% for Q4 (<275.0pg/mL) (P-trend<.001), as did T2DM complications. ROC analysis showed an OIF of <343.4pg/mL was predictive of DN (C statistic 0.702). OIF <343.4pg/mL remained predictive of microalbuminuria (odds ratio=11.60; 95% confidence interval: 1.25-107.47) after adjusting for confounding factors. Serum OIF is an independent diagnostic marker of DN.