The prevalence of Gilbert ́s syndrome (defined phenotypically based on serum bilirubin concentrations above 17.1 μmol/L in the absence of overt hemolysis and abnormal ALT activities) in patients with T2DM was significantly lower in the overall population (5.5 vs. 26%, p < 0.001), as well as in both men (5.7 vs. 30.2, p < 0.001) and women (5.3 vs. 20.6, p < 0.001), compared to our control population selected for their healthy status. The gene discussed is GPT; the disease is type 2 diabetes mellitus.