CYP7A1 and obesity due to melanocortin 4 receptor deficiency: Research has demonstrated that an elevated ratio of 12α-OH BAs to non-12α-OH BAs in serum, which is associated with T2DM, obesity, and IR, may be attributed to an underlying mechanism whereby abnormally elevated glucose and insulin levels induce histone acetylation on the chromatin of CYP7A1, thereby stimulating CYP7A1 synthesis and subsequently leading to an upregulation in the production of 12α-hydroxylated BAs (60–62).