Treatment compliance of research participants will be measured by pill counts. Research participants will be instructed to bring opened, unopened and empty investigational medicinal product packages to each visit in order to allow the assessment of compliance with study treatment. A record of all investigational medicinal product dispensed and returned will be documented on the investigational medicinal product dispensing and accountability log. Blood taken during stages when the participant is expected to be taking drug therapy will be used for future determination of plasma glucose and glycated haemoglobin concentrations. These concentrations will also be used to help ascertain compliance with the allocated treatment regimen.