This study will determine the effect of concomitant administration of sitagliptin and metformin on post-meal incretin hormone concentrations in healthy adults.

Inclusion Criteria:

• Subject is in good health
• Subject has been a nonsmoker for at least 6 months
• Subject is willing to avoid strenuous activity from the screening visit until the end of the study
• Subject agrees not to consume grapefruit products during the study and to avoid all fruit juices 24 hours before and after study drug administration

Exclusion Criteria:

• Any history of stroke or neurological disorder
• Subject has a history of cardiovascular, blood, endocrine or liver diseases
• Subject has a history of cancer