Diabetes · tablets & insulin
Diabetes Tablets & Insulin Before Surgery
Every diabetes medicine — tablets and insulin — is handled differently before surgery. Tick what you take to see the usual advice for each, then confirm your plan with your team.
On insulin? It's covered below. For the full by-type breakdown see the insulin on surgery day tool.
Frequently asked questions
Do I stop my diabetes tablets before surgery?
It depends on the type. SGLT2 inhibitors (Jardiance, Farxiga, Invokana) are usually stopped 3–4 days before surgery; sulfonylureas and metformin are usually held on the day of surgery. Never stop diabetes medicines without a plan for your blood sugar.
Why stop Jardiance or Farxiga before surgery?
SGLT2 inhibitors can cause ketoacidosis (DKA) even when blood sugar looks near-normal — called euglycaemic DKA. Because of this risk, they are usually stopped about 3–4 days before surgery. Confirm the exact timing with your team.
Should I take my sulfonylurea on the morning of surgery?
Usually no. Sulfonylureas (glimepiride, glipizide, gliclazide) can cause low blood sugar while you're fasting, so they're typically held on the day of surgery.
What about my insulin before surgery?
Insulin is adjusted, not stopped. Long-acting (basal) insulin is usually reduced — many teams advise about 80% of the usual dose — and mealtime (rapid) insulin is held while you fast because there's no food to cover. Premixed insulin is often halved on the morning, and insulin pumps usually keep running. If you have type 1 diabetes you must never stop all your insulin, as that can cause DKA. This checker covers insulin too — tick yours, and see the insulin on surgery day tool for full detail.