This multicentre , double-blind , active-controlled study randomized 2639 patients aged 18-80 years to 104 weeks of treatment with metformin in addition to alogliptin 12.5 mg once daily ( n = 880 ) , alogliptin 25 mg once daily ( n = 885 ) or glipizide 5 mg once daily , titrated to a maximum of 20 mg ( n = 874 ) .