Serum RBP4 levels correlated significantly and directly with fasting serum glucose levels (P < 0.05, r2 = 0.24; Figure 2(a)) but not with insulin levels and HOMA index (P = 0.13 and P = 0.08, resp.; Figures 2(b) and 2(c)) in HD group. Here, RBP4 is linked to Huntington disease.