RBP4 and type 2 diabetes mellitus: In a multivariate analysis, homozygosity for the M allele remained an independent predictor of lower RBP4 levels (P = 0.009, Table 2) after adjustment for factors previously associated with RBP4 plasma levels (age, gender, non-alcoholic steatohepatitis, body mass index and type 2 diabetes/impaired fasting glucose).