Januvia belongs to a new breakthrough class of prescription medications called dipeptidyl peptidase-4 (DPP-4) inhibitors that improves blood sugar control in patients with type 2 diabetes. Januvia enhances a natural body system called the incretin system, which helps to regulate glucose by affecting the beta cells and alpha cells in the pancreas. Through DPP-4 inhibition, Januvia works only when blood sugar is elevated to address diminished insulin due to beta-cell dysfunction and uncontrolled production of glucose by the liver due to alpha-cell and beta-cell dysfunction.