Patients aged 18 years with glycated hemoglobin ( HbA1c ) > 6.5 % to 10.0 % receiving stable metformin doses ( 1500mg/d ) were randomized 1:1 to add-on therapy with saxagliptin 5mg/d or glipizide 5 to 20mg/d ( titrated to optimal effect or highest tolerable dose during the initial 18 weeks ) .