RBP4 and diabetes mellitus: Other biomarkers have also been evaluated and used for the prediction of diabetes, including adiponectin,(5) leptin,(13,14) glycoalbumin,(15) and retinol binding protein 4 (RBP4).(16,17) Fat accumulation in the human body releases several adipokines from adipocytes, and some of these adipokines are known to aggravate insulin resistance, cause metabolic syndrome, and promote T2D.