Type 2 diabetes, added to metformin, a sulfonylurea, a glitazone or insulin, or used alone when metformin cannot be taken, to improve blood sugar control alongside diet and exercise.

After a meal the gut releases incretin hormones that tell the pancreas to make insulin and tell the liver to stop pouring out glucose. An enzyme called DPP-4 breaks those hormones down within minutes. Sitagliptin blocks that enzyme, so the body's own incretins last longer and act only when a meal has actually been eaten, which is why it seldom causes hypoglycaemia by itself.

Headache, stuffy or runny nose, sore throat, nausea and stomach discomfort. Low blood sugar mainly occurs when it is combined with a sulfonylurea or insulin.

Stop and seek urgent help for severe, persistent abdominal pain that may spread to the back, as pancreatitis has been reported. Report joint pain that is severe and lasting, or a blistering rash. The dose is reduced in kidney disease, so kidney function is checked before and during treatment. Tell your doctor about a history of pancreatitis, gallstones, or heavy alcohol use. It is a prescription medicine in Pakistan.