Retinol-binding protein 4, insulin resistance and pregnancy

Abstract

Sir, the recent publication on retinol-binding protein 4 (RBP4), insulin resistance (IR) and pregnancy is very interesting [1]. Khovidhunkit et al concluded, “Serum RBP4 levels in pregnancy are not associated with IR.” [1]. This report is very interesting but is discordant with previous reports. RBP4 is discussed in terms of its clinical correlation to gestational diabetes mellitus (GDM) and other metabolic disorders in pregnancy [2]. Increased RBP4 levels are observed in GDM. Inoue et al also mentioned that circulating RBP4 was elevated in cases of pregnancy-induced hypertension due to altered glucose metabolism [3]. A previous report by Choi et al reported, “Severity of glucose intolerance in women with pGDM is associated with high RBP4 and low adiponectin concentrations.” [4]. A similar report on the significant correlations of RBP4 was also published by Chan et al [5]. The differences in findings among the reports in this area reflect current discrepancies in this issue. There are some points to be considered. First, there are differences in subjects' backgrounds (including both genetic and environmental factors). In addition, the measurement techniques for RBP4 and other parameters differ (analyzer, quality control, etc.). Additionally, there are confounding conditions that lead to fluctuations in RBP4 levels (e.g., uric acid metabolism) [6,7]. These factors must be considered in assessment studies [8-14].