A Study of the Effects of Co-Administration of Sitagliptin (MK-0431) and Metformin on Incretin Hormone Concentrations (MK-0431-110)

Inclusion Criteria: * Female subjects must have a negative pregnancy test * Subject has type 2 diabetes and is not currently receiving treatment with an oral AHA agent, has not received such treatment for 3 months prior to study, and/or has not received more than 4 total weeks treatment with an oral AHA agent for 12 to 18 months prior to the study * Subject is a nonsmoker or has not smoked and/or used nicotine for at least 6 months Exclusion Criteria: * Subject has a history of stroke, seizures, or major neurological disorders * Female subject is breastfeeding * Subject cannot refrain from use of any prescription or non-prescription drugs beginning 2 weeks prior to first dose of study drug * Subject consumes more than 3 alcoholic beverages per day * Subject consumes more than 6 caffeinated beverages per day * Subject has had major surgery, or has donated or lost 1 unit of blood within 4 weeks of screening * Subject has a history of cancer, except certain skin or cervical cancer or other cancers treated more than 10 years prior to screening * Subject has a history of multiple and/or severe allergies or intolerance to drugs or food