METHODS: DIA-RAMADAN (NCT04132934) was a prospective, international, observational study conducted in nine countries. Patients >18 years of age with T2DM (N = 1244) were examined at an inclusion visit (V0) occurring 6-8 weeks before the start of Ramadan. Patients received a diary to report treatment changes, hypoglycaemic events (HEs), and other adverse events. Gliclazide MR was taken once daily for 14-18 weeks. A second visit (V1) was conducted 4-6 weeks after the end of Ramadan. The primary endpoint was the proportion of patients reporting ≥1 symptomatic HE. Changes in HbA1c, fasting plasma glucose (FPG), and body weight were secondary endpoints.

METHODS: Subjects (n = 121) received oral repaglinide (4 mg). Blood samples were taken at 0, 30, 60, 120, 180 and 240 min and serum concentrations of repaglinide were determined using high-performance liquid chromatography. Subjects were also genotyped by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) for CYP3A4*4, *5 and*18 and by an allele-specific multiplex PCR for CYP2C8*2, *3, *4 and *5 alleles.

RESULTS: The allele frequencies of CYP2C8*1, *2, *3, *4 and *5 were 95.04, 0.40, 0.40, 0 and 4.13%, respectively. The frequencies of the CYP3A4*1, *4, *5 and *18 alleles were 97.93, 0, 0 and 2.07%, respectively. CYP2C8 and CYP3A4 genotypes were not significantly associated with repaglinide's blood glucose-lowering effect. However, the CYP3A4 genotype significantly influenced some of repaglinide's pharmacokinetics, where the mean elimination rate constant was 44.0% lower (p = 0.04) and the mean half-life was 33.8% higher (p = 0.04) in subjects with the CYP3A4*1/*18 genotype as compared to those with the normal CYP3A4*1/*1 genotype. This result confirms that CYP3A4 plays a large role in metabolizing repaglinide.