If you have diabetes and you are pricing a knee, hip or shoulder replacement, the number that will shape your timeline is your hemoglobin A1c. Surgeons care about it for one main reason: high blood sugar is linked to infection of the new joint, and an infected implant can mean months of antibiotics and one or more extra operations.
There is no single A1c cutoff that every surgeon agrees on. The research points to a zone, roughly 7% to 8%, above which infection risk appears to climb. This guide covers what the studies actually found, how blood sugar is handled around the operation, what to pack if you fly to Colombia with insulin or a pump, and how to get your numbers where they need to be before you book anything.
Why blood sugar matters for a new joint
A joint replacement puts a large metal and plastic implant inside your body. If bacteria settle on it, the result is a periprosthetic joint infection (PJI), the complication orthopedic surgeons worry about most. Treatment often means washing out the joint or removing the implant, a long course of antibiotics and a second (or third) surgery. If you want to know what early infection looks like, read our guide to joint replacement infection warning signs.
The evidence is real but messier than many patients expect. A 2021 evidence review for family physicians described the link between diabetes and PJI after hip or knee replacement as limited in strength, and found no A1c goal that has been proven to reduce infection.1 Orthopedic researchers have studied both long-term control (A1c, fructosamine) and short-term spikes right after surgery, and both show up as risk markers in the literature.2 That uncertainty is why one surgeon's cutoff can differ from the next.
What the studies found about A1c and infection
A handful of studies come up again and again when surgeons explain their cutoffs. They do not agree perfectly.
| Study | Who was studied | What it found |
|---|---|---|
| Tarabichi et al., 2017 (multicenter) | 1,645 patients with diabetes | Best cutoff for predicting PJI was 7.7%. Infection rate was 0.8% below it and 5.4% above it.1 |
| Cancienne et al., 2017 | 7,736 patients | Infection in 2.4% of patients with A1c of 7.5% or higher vs 1.0% below that level.1 |
| Shohat et al., 2018 (meta-analysis) | Six studies using A1c cutoffs | A1c above 7% was not significantly associated with infection when the studies were pooled; results varied widely between studies.1 |
| Harris et al., 2013 | Joint replacement patients | A1c of 7% or higher was linked to more complications overall but not to PJI. A strict 7% rule would have delayed surgery for about 32% of patients.3 |
| Godshaw et al., 2018 | Patients having joint replacement | A1c above 7.45% was linked to post-surgery glucose above 200 mg/dL, but not to more PJI.3 |
The practical reading: A1c is a blunt tool. Risk does not flip from safe to dangerous at one decimal point, but infection appears noticeably more likely once you are in the high 7s and above. The AAFP review's bottom line was that keeping A1c below 7.5% around surgery may reduce PJI risk, a recommendation it graded as resting on limited evidence.1
Where the "7%" and "7.5%" numbers come from
- Around 7%. Major diabetes organizations support long-term A1c targets of roughly 6.5% to 7% for many adults. Those are general health goals, not surgical cutoffs.1 Some surgeons borrow them anyway. In one study of 404 joint replacement candidates with diabetes, patients asked to reach an A1c below 7% took an average of 8 months to get there, and some took up to 3 years.3
- 7.5% to 7.7%. These come from the infection studies above and are common orthopedic cutoffs.
- Other numbers. Some practices and hospitals use a higher general cutoff for elective surgery. Ask which number your surgeon uses and whether it is a hard stop or a discussion point.
The International Consensus Meeting on PJI is the most widely cited reference on joint infection prevention, and summaries that draw on it treat blood sugar control as a modifiable risk to fix before elective surgery. One such summary, by Goh and Parvizi in 2021, notes that A1c is the standard test but that it is not clear it is the best marker for deciding who is ready.4
Fructosamine: the test some surgeons add
A1c is a long-run average and moves slowly. Fructosamine reflects a shorter window of a few weeks, which makes it useful when you are actively improving your numbers or when A1c may be unreliable, such as with some types of anemia. In a prospective study of 1,212 hip replacement patients presented in 2020, a fructosamine above 293 µmol/L was tied to roughly six times the rate of joint infection, and the link held after adjusting for A1c.5 Many patients with high fructosamine in that study did not know they had prediabetes or diabetes.5 Goh and Parvizi also point to multicenter work in which fructosamine predicted complications better than A1c.4 If your A1c is borderline, ask whether the surgeon accepts or wants a fructosamine result too.
Blood sugar on the day of surgery and after
Long-term control is only half the picture. Glucose spikes around the operation matter too. The CDC's 2017 guideline on preventing surgical site infections recommends perioperative blood glucose targets below 200 mg/dL.6 A 2025 review of glucose control in orthopedic surgery lists the American Diabetes Association's hospital target as 80 to 180 mg/dL and suggests that a range around 110 to 150 mg/dL may limit infection risk while avoiding dangerous lows.3 Big swings matter as well: higher glucose variability after joint replacement has been associated with worse outcomes.2
What this means for you in practice:
- Expect your glucose to be checked before anesthesia and several times in the first days after surgery.
- Expect possible insulin in the hospital, even if you normally use only pills.
- Ask in advance who manages your diabetes on the ward: the surgeon, an internist or an endocrinologist.
- Ask whether you can keep wearing your continuous glucose monitor (CGM) and pump, and what happens to them in the operating room.
- Pain, stress, poor sleep and some medicines given around surgery can push numbers up for a few days. Plan for it rather than being surprised.
Medications that may need to stop first
Some diabetes drugs need a pause before anesthesia. The decision belongs to your prescriber and anesthesiologist, but you should know to ask about two groups:
- SGLT2 inhibitors (canagliflozin, dapagliflozin, empagliflozin, ertugliflozin). In 2020 the FDA approved label changes advising that these be stopped before scheduled surgery to reduce the risk of diabetic ketoacidosis: at least 3 days ahead for the first three and at least 4 days for ertugliflozin.7
- GLP-1 drugs (semaglutide, tirzepatide and others). These slow stomach emptying, which matters for anesthesia. We cover them in detail in GLP-1 medications before joint replacement.
Insulin doses, especially long-acting insulin, are often adjusted the night before and the morning of surgery while you are fasting. Get those instructions in writing from the team operating on you, in the language you read best.
What a Colombian surgeon will usually ask for
Policies vary by surgeon and hospital in Colombia, just as they do in the US, so do not assume one practice's cutoff applies to another. Before you put down a deposit, expect to send or be asked for:
- A recent A1c (ask exactly how recent it must be) and, if they use it, a fructosamine.
- Your full medication list with doses, including your insulin regimen and any pump or CGM details.
- Kidney function and other routine pre-op labs, since diabetes can affect the kidneys and the drugs used around surgery.
- A note from your primary care doctor or endocrinologist describing your diabetes, or a pre-surgical medical evaluation done locally on arrival.
- Information on diabetes complications: neuropathy, foot wounds, heart disease, eye disease.
Ask the surgeon three direct questions: what A1c cutoff they use, whether they repeat it on arrival, and what happens to your surgery date (and your deposit) if your number is too high when they test it in Colombia. Put the answers in your quote packet so they are in writing.
Flying with insulin, a pump or a CGM
Airport security in the US
Insulin, pens, syringes, pumps, CGMs and related supplies are allowed through TSA checkpoints. Insulin and other medical liquids can exceed the usual 3.4-ounce limit, but you need to take them out, declare them and keep them separate from your regular quart bag of liquids. Prescription labels are not required, though they can speed things up if you get extra screening.8
Devices are the trickier part. Medtronic advises users of its pumps and CGMs not to send them through the X-ray machine or a full-body scanner, and to ask for an alternative screening instead. It says walking through a standard metal detector while wearing the devices is fine.9 Other manufacturers have their own instructions, so check yours before you fly. Tell the officer up front that you have diabetes, wear a device and are carrying supplies.9
Packing and paperwork
- Keep all insulin and supplies in your carry-on. Never check insulin; temperature and pressure changes can affect it.8
- Pack enough for the whole trip plus several extra days for delays, in the original containers.10 Recovery can run longer than planned, so err on the side of more.
- Get a letter on your doctor's letterhead listing your conditions, medications with generic names and doses, allergies and the equipment you need.10
- Pack backups for a pump or CGM failure: pens or syringes and a meter with strips.
- Carry fast-acting glucose for the flight and for the days after surgery when meals are irregular.
Your insulin brand may be sold under a different name or strength abroad. Do not plan on buying it locally unless your doctor has confirmed an equivalent in advance.
The flight home
After surgery you may be on new pain medication and a blood thinner, moving less and eating less than usual, all of which can change your glucose. Check more often on travel day, keep snacks within reach and arrange wheelchair or mobility help in advance. Ask your surgeon how long to wait before flying and how they manage clot risk on the trip home.
A realistic timeline for getting your numbers ready
Because A1c moves slowly, a big improvement does not show up in a week or two. In the study above, reaching a 7% goal took an average of 8 months.3 Work backward from your target surgery date and leave slack.
- 6 or more months out. Get a current A1c. Ask your surgeon or the Colombian practice what cutoff they use. If you are above it, see your diabetes doctor now about medication changes, diet and whatever activity your joint allows.
- 3 months out. Recheck A1c. If it is coming down but not there yet, hold off on nonrefundable flights. Ask whether a fructosamine test can show recent progress.
- 6 to 8 weeks out. Confirm the surgeon accepts your latest result. Work out your plan for SGLT2 drugs, GLP-1 drugs and insulin with your prescriber. Book travel only once the date is confirmed.
- 2 to 4 weeks out. Finish other pre-op items, including any dental work your surgeon wants done first. Order extra supplies and get your doctor's travel letter.
- Arrival in Colombia. Expect repeat labs. Bring your records in printed and digital form.
Very high blood sugar with vomiting, deep or rapid breathing, confusion or extreme drowsiness can signal diabetic ketoacidosis, which is an emergency. So is a low blood sugar you cannot treat yourself. Get emergency care immediately, in Colombia or at home.
If your number is too high: what not to do
A delay feels expensive when you are in pain and have a plan. But pushing through with poor control trades a few months of waiting for a higher chance of the one complication that can turn a single surgery into several.
Reasonable moves
- Ask for a clear target and a recheck date.
- Work with your diabetes doctor on a specific plan.
- Use the wait for prehab exercises your surgeon or physical therapist approves.
- Look at weight and other modifiable factors too.
Moves to avoid
- Choosing a surgeon purely because they skip the A1c check.
- Crash dieting or big medication changes without supervision right before surgery.
- Booking nonrefundable travel before your number is accepted.
- Assuming the same cutoff applies at every hospital.
Weight, age and other health factors interact with diabetes when surgeons weigh risk. Our article on age, BMI and joint replacement outcomes covers those. When you are ready to compare practices, you can request a quote and include your latest A1c so the answer reflects your real situation.