This study is being carried out to see if dapagliflozin and dapagliflozin plus saxagliptin as an addition to metformin is effective and safe in treating patients with type 2 diabetes when compared to glimepiride (sulphonylurea) as an addition to metformin treatment.

Inclusion Criteria: Main Inclusion Criteria:

1. Is male or female and ≥18 and <75 years old at time of informed consent.
2. Has a HbA1c of ≥7.5% and ≤10.5% based on central laboratory results from Visit 1, with individual need for therapy escalation.
3. Currently treated with a stable maximum tolarated dose (MTD) (≥1500 mg/day) of metformin therapy for at least 8 weeks prior to Enrolment visit.
4. Has a BMI of ≤45 kg/m2 at Enrolment visit.
5. Has a C-peptide laboratory value of ≥1.0 ng/mL (0.33 nmol/L; 333.3 pmol/L) based on central laboratory results from Visit 1.

Main, Exclusion Criteria:

1. Clinically diagnosed with Type I diabetes, known diagnosis of maturity onset diabetes of the young (MODY), or secondary diabetes mellitus or known presence of glutamate decarboxylase 65 (GAD65) antibodies.
2. Patients who, in the judgment of the Investigator, may be at risk for dehydration or volume depletion that may affect the patient's safety and/or the interpretation of efficacy or safety data.
3. Clinically significant cardiovascular disease or procedure within 3 months prior to Enrolment or expected to require coronary revascularization procedure during the course of the study.
4. Concomitant treatment with loop diuretics