Sitagliptin
Sitagliptin is an oral antidiabetic drug of the DPP-4 inhibitor class. It blocks the enzyme that breaks down incretin hormones, so insulin release rises and glucagon falls when blood glucose is high, which mostly limits its effect to after meals. It is used in type 2 diabetes to improve blood sugar control, alone or alongside other glucose-lowering drugs.
Food does not affect absorption, so the tablet can be taken with or without a meal at whichever time of day is easiest to keep regular. The drug leaves the body mainly through the kidneys, which is why kidney function matters and why creatinine and eGFR are checked along with HbA1c and glucose. On its own it rarely causes low blood sugar, but combined with insulin or sulfonylureas the risk of hypoglycaemia goes up.
Severe, persistent abdominal pain radiating to the back, especially with vomiting, is the sign of possible pancreatitis and means stopping guessing and seeing a doctor. Rash with blistering, swelling of the face or lips, or a marked fall in urine output also warrants prompt medical review.
Reference information, not medical advice. Discuss any change with your doctor.