<qa>  How many patients with type 2 diabetes will be recruited to a randomised double-blindThis study will test 2 hypotheses of drug response supported by routine clinical and trial data. 600 patients with type 2 diabetes who have suboptimal glycaemic control on dual oral therapy will be recruited to a randomised double-blind crossover study of a DPP4 inhibitor, SGLT2 inhibitor and thiazolidinedione. Each patient will take each study drug in addition to their existing treatment for four months at a time. At the end of each treatment the patients glucose control will be measured and information about their experience of the drug will be collected. 