CYP2D6 and Hyperglycemia: There are several reasonable hypotheses regarding the mechanism by AP caused by olanzapine: (i) metabolic adverse reactions, especially hyperlipidemia, hyperglycemia, and weight gain, may indirectly induce AP (Weston-Green et al., 2012; Sussman, 2003; Albaugh et al., 2012); (ii) Genetic variations, especially polymorphisms in the CYP2D6, CYP1A2, UGT1A4, and FMO3 coding genes, may affect the metabolism of olanzapine (Ustohal et al., 2016; Lett et al., 2012).