Do You Need to Remove Your Insulin Pump or CGM for Eye Surgery?
Your Pump, Your Sensor, and Eye Surgery at a Glance
For most eye surgery, you keep your pump on and your sensor on. Eye surgery is short. You are usually awake. The work is on your eye, far from where your devices sit.
National diabetes care standards say a person using an insulin pump may keep using it during surgery when that fits the hospital's policies and the operation itself1. Sensor use should also carry on in hospital when it is clinically right, with a finger stick used to confirm before insulin is dosed2.
The choice is not yours alone, and it is not made on the day. Do not stop your insulin just because you were told not to eat. Ask for a written plan at your pre-surgery visit. For most people the answer is to keep both devices on and come in early.
Eye operations sit at the mild end of surgery. That is much of why the devices usually stay on.
Most cataract and glaucoma procedures use monitored anesthesia care with numbing drops and a local block, not full general anesthesia3. Cataract surgery is done in an outpatient center or a hospital. The eye is numbed with drops or an injection, you stay awake, and you rest about 15 to 30 minutes before going home4.
Short, awake, and finished in a morning. That is the profile that lets a pump and a sensor stay put.
What Insulin Pumps and Glucose Sensors Actually Do
A pump delivers insulin under your skin all day, through fine tubing or from a patch. It gives a slow background trickle, called basal insulin, plus larger amounts at meals.
A pump infuses only rapid-acting insulin under the skin5. If delivery stops, no slow-release insulin is left in your body, the way it is for someone who injects a long-acting insulin once a day.
That is why guidance says normal basal insulin is continued before surgery rather than held. People with type 1 diabetes need insulin at all times, including while fasting6. The risk on the day is a pump that quietly stops, and a named person watching the numbers is what protects you.
A continuous glucose monitor, or CGM, is a small sensor worn on the arm or belly. It reads sugar in the fluid just under your skin (clinical: interstitial fluid), not sugar drawn from a vein.
The sensor samples glucose every 5 minutes and sends readings to a reader, a phone app, or the pump. Sensors are usually replaced every 7 to 14 days5. In a hybrid closed loop system, the pump then adjusts its own background insulin in response to those readings5.
Because it samples fluid, a sensor runs slightly behind a finger stick. That lag is harmless on an ordinary day, and it is one reason your team adds finger sticks.
Eye surgery covers a wide range, and the device answer shifts with the size of the job.
Over time more than half of people with diabetes develop diabetic retinopathy. Treatments include anti-VEGF medicine injected into the eye, laser to shrink leaking vessels, and a vitrectomy for eyes with heavy bleeding or scarring7.
| Eye procedure | Usual anesthesia | Usual starting point |
|---|---|---|
| Injection in the clinic. | Numbing drops only. | Both stay on. |
| Laser for the retina. | Drops, sometimes a block. | Both stay on. |
| Cataract or glaucoma surgery. | Sedation plus numbing. | Usually both stay on. |
| Vitrectomy. | Often a block plus general. | Discuss it in advance. |
Treat that as a starting point for your conversation, not a decision. Your own answer depends on your operation and your hospital's policy.
Who Can Keep Their Devices On Through Eye Surgery
If your eye operation is short, you stay awake, and your diabetes has been steady, you are the standard candidate for keeping everything on.
Guidance describes continuing a pump through a minor procedure where the site is intact and under 3 days old, the reservoir holds enough insulin, and pump function and settings are appropriate6. A society consensus statement also advises avoiding removal of a glucose sensor where possible, because taking it off interrupts sensor-informed treatment8.
Cataract surgery fits that description well. So does most laser and injection work.
Underneath the paperwork, your team is asking whether this device can run safely for an hour or two while you are occupied.
Preoperative tasks include checking the pump's function, its battery life and insulin supply, and the accuracy of the sensor. Endocrinology, pre-op nursing and the anesthesia team work through this together5.
A sore site, a low reservoir, or a pump that has alarmed all week counts against you. This is a checklist, not an exam you can fail for good. Most people who do not pass it change a site or sensor a day early.
A few situations push the team toward taking the pump off and running your insulin themselves.
Magnetic resonance imaging is described as an absolute contraindication for insulin pumps. Ionizing radiation, such as computed tomography and nuclear medicine scans, and cardiac procedures are relative ones6.
Very little eye surgery falls into those groups. If yours does, the plan is never that you go without insulin. It is insulin given another way, watched more closely.
What to Settle at Your Pre-Surgery Visit
The pre-surgery visit is where the device plan should be written down and handed to you.
Guidance describes endocrinologists, pre-op nursing staff and anesthetists working together to fine-tune the insulin regimen, review other diabetes medicines, and build a safe anesthesia plan5. A society expert consensus statement was written for this situation, because insulin-treated patients now commonly arrive already wearing these devices8.
Ask who is writing your plan, and ask for a copy. One sheet of paper prevents most of what goes wrong.
Being early on the operating list is the most useful thing you can request.
The usual fasting rules still apply. Surgery is preferably booked early to limit time with nothing by mouth, and where that is not possible, closer glucose monitoring and insulin adjustment may be needed instead5.
A late slot means a long fast on a day your insulin plan has already been altered. That is where most lows come from.
Pack as though you may need to change a site or treat a low while you are there.
- A spare infusion set, reservoir, and sensor.
- Your finger stick meter and test strips.
- Chargers for your pump, phone, or reader.
- Fast-acting sugar for a low, plus your usual snack.
- A written note of your basal settings and usual doses.
- Any backup injectable insulin your team asked you to bring.
Most people never open the bag. Packing it the night before also gives you a last chance to notice that a sensor expires tomorrow.
How Your Blood Sugar Is Managed on Surgery Day
You will be told not to eat, and you will still need insulin running. Both are correct at once, and that confuses a lot of people.
Your team may lower your background rate for the fasting hours, and that change is theirs to make in advance. The reasoning is that basal insulin is continued rather than held, because people with type 1 diabetes need insulin at all times6.
If nobody has given you a fasting-day plan, phone and ask. The pre-op nurse hears that question every week.
Once the drapes are on, your blood sugar becomes the team's job rather than yours.
National standards set a blood glucose range of 100 to 180 mg/dL before, during and after surgery. They advise checking at least every 2 to 4 hours while a person takes nothing by mouth1. Where a sensor cannot be used, guidance advises a finger stick every 1 to 2 hours instead5.
For a short awake eye operation, that usually means one check before and one after. You are simply not away from food for very long.
Your sensor can stay on and the team will still confirm it with a finger stick. Both are true at once.
Perioperative guidance notes that sensors have not been approved or validated by the Food and Drug Administration for perioperative or inpatient use, and that accuracy can fall with fast-changing glucose, pressure on the sensor, low body temperature, low blood pressure, swelling, low oxygen and certain medicines5. Standards therefore pair continued sensor use with a confirming finger stick before insulin is dosed2.
An operating room is close to the least reliable place a sensor will ever work, and a finger stick takes seconds.
Positioning is the easy part of eye surgery. The surgical field is your face, and your devices are nowhere near it.
The general rule is that devices go outside the surgical field, on a part of the body not being leaned on, and away from the surgical and electrosurgical grounding sites6. Where a pump keeps running, it and its site should be securely fastened and easy to reach5.
An arm sensor or belly site sits well clear of an eye. Point out where each one is when you arrive.
When a Pump or Sensor Has to Come Off
The firmest removal rules come from the device makers. They are about scanners and heat, not about eye surgery.
Dexcom instructs users not to wear any Dexcom G6 part during magnetic resonance imaging, a computed tomography scan, or diathermy, and to stop the sensor session and remove the sensor first9. Abbott states its newer FreeStyle Libre 2, 2 Plus, 3 and 3 Plus sensors are not affected by common imaging, though readings may be unreliable during an MRI, with normal function back after 1 hour. The older 14 day system had to be removed, and the diathermy rule is unchanged10.
The rules differ by brand and model, and they have genuinely changed. Read the instructions for your own device, and show them to your team.
A longer operation under general anesthesia shifts the balance toward the team running your insulin.
In the United States, people having vitreoretinal surgery typically get a mix of regional and general anesthesia, because topical numbing does not suit the length of those procedures3.
If your operation is the longer kind, expect a fuller diabetes plan and more monitoring. That is careful planning, not a warning.
If the pump comes off, insulin does not stop. It arrives another way, and arranging that in advance is why this conversation happens early.
Where a pump is disconnected, the described approach is to start an insulin drip into a vein within 30 minutes to provide background cover6. Standards say that if a pump cannot be used during surgery, an alternative plan of an insulin infusion, or basal plus correctional insulin, is started before surgery1.
Ask who reconnects you and when. Handover from the operating room to recovery is where a disconnected pump is most often forgotten.
The First Hours and Days After Eye Surgery
Most people are back on their normal settings the same day, often before leaving the building.
Guidance is to keep testing after surgery, to put preoperative basal rates back as the usual diet resumes, and to give meal doses with corrections for high readings5.
Do not assume your settings were restored. Check the pump yourself, or ask someone to check with you, before you go home.
Eye surgery barely changes how you eat, which is why blood sugar usually settles quickly.
After cataract surgery you may need eye drops, and your ophthalmologist may ask you to wear glasses or a shield to protect the eye, including a shield while you sleep4. None of that stops you wearing a pump or sensor.
What changes is your eye routine, not your diabetes routine. Blurry days do make a small pump screen harder to read, so change your site and sensor before surgery rather than after, and turn on audible alerts.
What Can Go Wrong, and How Often
The most common diabetes problem around any operation is a low, and it comes from the fasting rather than the surgery.
You cannot reliably feel a low once you have had sedation, so the team monitors on a schedule instead. Standards advise a blood glucose check at least every 2 to 4 hours while you take nothing by mouth1. Guidance handles a low by reducing the pump's background rate and giving glucose by mouth or by vein5.
Managed that way, a low is usually spotted as a number on a meter and treated within minutes.
The less common but more serious problem is insulin delivery stopping quietly.
A pump carries only fast-acting insulin, so a site or set that fails leaves you with none on board within hours. That is the stated reason basal insulin is continued rather than held, and the reason insulin is restarted another way promptly when a pump comes off6. Guidance also advises checking for site problems and pump malfunction whenever readings run high5.
The protection is mostly logistical: a fresh site before surgery, a named person watching the numbers, and an agreed restart plan.
A raised A1c does not automatically cancel eye surgery. The largest study of this in cataract surgery is reassuring.
Among 190,393 United States veterans with diabetes who had cataract surgery with an A1c measured in the 6 months beforehand, 157 developed an acute infection inside the eye afterward, roughly 8 of every 10,000. Mean A1c was 7.1 percent in that group against 7.3 percent in those without it, a gap that did not reach statistical significance11. Standards still suggest a preoperative A1c goal below 8 percent within 3 months of elective surgery, weighed case by case1.
Read those together. One large record review found no link with that particular infection, while the general advice to settle your control before elective surgery still stands.
When to Call Your Doctor After Eye Surgery
A few symptoms after eye surgery mean you should be seen the same day rather than at your booked visit. Call your eye surgeon the same day, or go to an emergency room if you cannot reach them, for any of these in the operated eye:
- Vision that is getting worse rather than better.
- Severe eye pain your usual pain relief does not settle.
- A sudden increase in floaters, or new flashing lights.
- A dark shadow or curtain across part of your vision.
- Increasing redness, swelling around the eye, or thick discharge.
Most people never see any of these. They are listed because each one is treatable when caught early, and calling the same day is what buys that.
The diabetes side has its own same-day list, and nearly all of it traces back to insulin having stopped arriving.
Contact your diabetes team urgently if, in the day or two after surgery, readings stay high despite corrections, your ketones are raised, or you have nausea, vomiting, deep or fast breathing, or stomach pain. Follow the sick-day and pump-failure plan you already have while you make contact.
These are the same signs you were taught to act on long before surgery was booked. Acting early keeps it a phone call rather than an admission.
Much of what you notice after eye surgery is expected and can wait for the visit you already have.
Mild grittiness, a red patch on the white of the eye, blur that improves day by day, and mild sensitivity to light are all ordinary. Most people see better within a few days of cataract surgery, though full healing takes about 4 to 6 weeks, and your ophthalmologist will tell you when you can safely exercise, drive, or return to other activities4. Keep using the drops as directed, and save the milder things for the visit your surgeon has already booked.
If you cannot work out which list a symptom belongs on, call anyway. Clinics would rather answer that than see the result of a week of waiting.
Questions People Ask About Pumps, Sensors, and Eye Surgery
Usually not. Cataract surgery is short, done while you are awake, and nowhere near your infusion site. National diabetes standards state that pump use may continue during surgery when it fits the hospital's policies and the procedure1. Your surgical and diabetes teams still decide together, and the practical conditions are a fresh site, enough insulin in the reservoir, and a working pump.
In most cases yes, and the team will use a finger stick alongside it. Guidance is that sensors should be continued so long as there is no contraindication5, and a perioperative consensus statement advises against removing a sensor where that can be avoided8. The exceptions are scanners and heat treatments, not eye surgery. Tell the team where your sensor sits, since pressure on it can distort readings.
No. Fasting instructions are about food and drink, not your background insulin. Normal basal insulin is continued rather than held, because people with type 1 diabetes need insulin at all times, including while fasting6. Your team may agree a lower background rate for those hours, planned in advance. If you have no fasting-day plan in writing, phone the pre-op clinic and ask for one.
Change it beforehand. A site or sensor in its final hours is the most avoidable reason a device gets pulled on the day. Keeping a pump through a procedure assumes an intact site placed under 3 days earlier, and enough insulin in the reservoir for the whole period6. Changing both a day or two early, while you can see clearly, beats doing it in a pre-op bay.
Not necessarily, and the cataract surgery evidence does not support one fixed cut-off. In a review of 190,393 veterans with diabetes, A1c before surgery showed no significant link with acute infection inside the eye afterward11. Standards still suggest aiming below 8 percent in the 3 months before elective surgery, judged case by case1. Centers set their own policy, so ask yours directly.
It may, and nobody should rely on it by itself. A closed loop adjusts insulin from sensor readings, and sensor accuracy is what becomes least dependable in an operating room. Sensors are not validated for perioperative use, and accuracy can fall with fast glucose change, sensor pressure, low body temperature and low blood pressure5. Ask your team whether they want automatic mode left running or switched to a set rate.
More Questions About Devices, Anesthesia, and Recovery
Almost never. Anti-VEGF medicines for diabetic retinopathy are given as an injection into the eye7, and an injection visit involves no cutting, no diathermy and no scanner, so there is nothing your devices need protecting from. You normally eat as usual that day, so your insulin routine is unchanged. Confirm when you book, particularly if another procedure is combined with it.
The anesthesia team is, and it should be a named responsibility rather than an assumption. Guidance advises the team to ask the patient how their device works before anesthesia, and to keep a running pump secured and reachable5. Show someone how to suspend your pump before you go in, and say it out loud rather than only writing it on a form.
Tell a nurse straight away rather than silencing it and waiting until you get home. An alarm in recovery usually means a blockage, a low reservoir, or a loose site, and each of those means insulin has stopped arriving. Because a pump carries only fast-acting insulin, guidance restarts insulin another way promptly rather than waiting6. Your eye can wait a few minutes; the pump should not.
It can, and the effect is usually modest and short, because eye surgery is small and you eat again quickly. Guidance describes stress after surgery as variable, with testing continued, basal rates put back as your diet resumes, and corrections given for high readings5. Watch your readings for the first several days, and contact your diabetes team if they stay high.
Take this list to your pre-surgery visit and write the answers down, since the team who sees you on the day may not be the team who planned your care.
- Can my insulin pump keep running through this operation, and who makes the final call?
- Can my sensor stay on, and where should I place it so it is out of the way?
- Should my background rate change while I am fasting, and if so to what, in writing?
- Can I be scheduled early on the list so my fast is as short as possible?
- Who checks my blood sugar during and after the operation, and how often?
- If the pump has to come off, how will I get insulin, and who reconnects me?
- Should my closed loop stay in automatic mode, or move to a set rate?
- Which numbers or symptoms should make me call you rather than wait?
- When should I go back to my usual settings and my usual way of eating?
- American Diabetes Association Professional Practice Committee, Diabetes Care 2026;49(Suppl 1):S339, professional practice guideline (2026). 16. Diabetes Care in the Hospital: Standards of Care in Diabetes-2026 (Recommendations 16.14 and 16.15, perioperative care).
- American Diabetes Association Professional Practice Committee, Diabetes Care 2026;49(Suppl 1):S150, professional practice guideline (2026). 7. Diabetes Technology: Standards of Care in Diabetes-2026 (Recommendations 7.29 and 7.30).
- StatPearls Publishing, peer-reviewed clinical reference hosted by the National Library of Medicine (2024). Anesthesia for Ophthalmic Surgery (StatPearls).
- American Academy of Ophthalmology, patient education reviewed by ophthalmologists (2025). Cataract Surgery (EyeSmart patient education).
- Lal S, Khan E; World Federation of Societies of Anaesthesiologists, peer-edited educational tutorial, DOI 10.28923/atotw.524 (2024). Perioperative Management of Diabetic Patients: Optimising Care with Insulin Pumps and CGM Devices (Anaesthesia Tutorial of the Week 524).
- Duggar B, Hoagland M; OpenAnesthesia, peer-reviewed anesthesiology educational reference (International Anesthesia Research Society) (2024). Perioperative Management of Patients with Type 1 Diabetes Mellitus.
- National Eye Institute, National Institutes of Health, patient health information (2025). Diabetic Retinopathy.
- Society for Perioperative Assessment and Quality Improvement, Journal of Clinical Anesthesia 2024, multidisciplinary expert consensus statement, PMID 39388833 (2024). Perioperative Management of Adult Patients with Diabetes Wearing Devices: A Society for Perioperative Assessment and Quality Improvement (SPAQI) Expert Consensus Statement.
- Dexcom, Inc., manufacturer product safety instructions for its own device (2025). Can I use Dexcom G6 during an MRI, CT scan, or diathermy treatment?.
- Abbott Diabetes Care, manufacturer product safety information for its own device (2025). Why has the contraindication for MRI, CT-scan, and X-rays been removed for FreeStyle Libre 2, FreeStyle Libre 2 Plus, FreeStyle Libre 3 and FreeStyle Libre 3 Plus sensors?.
- Armbrust KR et al., Ophthalmology 2025;132(8):903-910, retrospective cohort study of the US Veterans Affairs Corporate Data Warehouse, PMID 40122400 (2025). Preoperative Glycemic Control and Acute Endophthalmitis after Cataract Surgery in United States Veterans with Diabetes Mellitus.