Kloting N, Graham TE, Berndt J, et al. Serum retinol-binding protein is more highly expressed in visceral than in subcutaneous adipose tissue and is a marker of intra-abdominal fat mass. Cell Metab. 2007; 6(1):79-87.
It may be possible to estimate a person's intra-abdominal fat by measuring blood levels of a chemical transporter for vitamin A. The transporter, retinol-binding protein (RBP4), may help identify patients with insulin resistance. RBP4 levels secreted by fat and liver cells increase in obese patients and in those with type 2 diabetes. In this study of 196 subjects, increased levels of RBPF were found in those with high amounts of intra-abdominal fat as well as in insulin-resistant subjects.
According to the authors, monitoring RBP4 levels may one day be used to provide a simple assessment of increased risk of insulin resistance and obesity.