This effect was mostly driven by omeprazole, which increased the odds of severe hypoglycemia over three-fold in patients with CYP2C19 NM/RM/UM phenotype treated with gliclazide [OR = 3.26 (1.44–7.38), p = 0.005] (Figure 5). This evidence concerns the gene CYP2C19 and Hypoglycemia.