Glucose ingested orally triggers a much greater release of insulin from the pancreas than would the same amount given
intravenously. Gastrointestinal hormones have been identified which are released in the presence of glucose in the gut and
trigger this enhanced insulin secretion. These hormones are known as the incretins. Patients with Type 2 diabetes have
been shown to have lower circulating levels or reduced activity of the incretins and this has prompted targeted drug development
with new anti-diabetic agents. DPP-4 inhibitors and incretin mimetics are the two new classes of drug developed
to target this system.