Safety and Efficacy of Saxagliptin Plus Insulin With or Without Metformin

Inclusion Criteria: * Type 2 diabetes mellitus * Must have been taking a stable dose of basal or premixed insulin for 8 weeks or longer prior to screening * If taking metformin, must have been taking the same daily dose for 8 weeks or longer prior to screening * Insulin type should be intermediate- or long-acting (basal) or premixed (premixed formulation may include short- or rapid-acting insulin as 1 component). * Inadequate glycemic control (A1C of 7.5% to 11.0%, inclusive) * Body mass index of 45 kg/m² or lower * Fasting C-peptide level of 0.8 ng/mL or higher Exclusion Criteria: * Symptoms of poorly controlled diabetes, including but not limited to marked polyuria and polydipsia with greater than 10% weight loss during the last 3 months prior to screening or other signs and symptoms * History of diabetic ketoacidosis or hyperosmolar nonketotic coma * Women of childbearing potential unable or unwilling to use acceptable birth control * Women who are pregnant or breastfeeding * Active liver disease * Anemia * Chronic or repeated intermittent corticosteroid treatment (participants receiving stable doses of replacement corticosteroid (except dexamethasone) therapy may be enrolled) * Use of short- or rapid-acting insulin * Significant cardiovascular history defined as: myocardial infarction, coronary angioplasty or bypass graft, valvular disease or repair, unstable angina pectoris, transient ischemic attack, or cerebrovascular accident * Congestive heart failure * Unstable or rapidly progressing renal disease * History of alcohol or drug abuse within the previous year * History of hemoglobinopathies * Unstable major psychiatric disorders * Immunocompromised status