The Importance of Glucose Control After Surgery: Why It Matters for Everyone

Short answer: After surgery, eat at regular times, put protein in every meal and save sugary drinks for treating a low. Surgery pushes blood sugar up, even without diabetes. Most teams aim for 100 to 180 mg/dL around surgery (1). Without diabetes, the rise usually peaks within a day and settles after about 3 days (2).

When we think of post-surgical recovery, pain, infection and getting moving usually come to mind first. Blood sugar is easy to overlook, yet it matters for everyone. This guide covers why it rises, the numbers your team may use, what to eat, what to expect week by week, and when to call. Your surgical team's instructions come first.

Why does blood sugar go up after surgery?

Surgery is a big stress on the body. It triggers stress hormones such as cortisol and adrenaline, and it makes your muscles less responsive to insulin for a while. Doctors call the result stress hyperglycemia. It can happen whether or not you have diabetes.

The insulin effect is larger than most people expect. In a small study of open gallbladder surgery, insulin sensitivity dropped by about 54% on the first day after the operation and was back to normal when it was measured again on day 20 (3). The bigger the operation, the bigger the drop tends to be (4). Bed rest and eating less add to it.

So a high reading in the hospital does not automatically mean you have diabetes. It does mean your team will want to watch it.

Why glucose control matters: infection and complications

High blood sugar around surgery is linked with more problems afterward. Here is what the research shows:

1. More infections. In 90,830 hip replacements, a blood sugar checked on the day of surgery, before the operation, of 277 mg/dL or more in people with diabetes, or 193 mg/dL or more in people without diabetes, was linked with higher odds of a joint infection within 90 days (6). US infection guidelines advise keeping glucose under 200 mg/dL during surgery for all patients, with or without diabetes (7).
2. Slower wound healing. High glucose makes it harder for white blood cells to fight germs, which is one reason wounds are watched closely when readings run high.
3. More complications overall. In 40,836 people having abdominal, vascular or spine surgery, people without diabetes whose blood sugar reached 180 mg/dL or more had 1.6 times the odds of a complication compared with those whose readings stayed normal (5).
4. Longer hospital stays. Complications are what usually keep people in the hospital longer and add extra treatments.

These studies show a link, not proof that lowering one number prevents every problem. Still, they explain why your team checks your sugar even if you have never had a high reading before.

The numbers your team may use

These are targets hospitals commonly use. They are here so you know what the numbers on your chart mean, not so you can manage your own treatment. Your team may set different goals for you.

Glucose control with diabetes vs. without diabetes

If you have diabetes

Managing blood sugar after surgery is already part of your routine, but surgery changes the rules for a few days. High readings can lead to complications, and lows can be just as dangerous, especially on fasting mornings. Hospitals often use frequent finger-stick checks, a continuous glucose monitor and insulin to keep you in range, even if you normally take only pills.

Some diabetes medicines need a plan before surgery. Ask your team about each one. The American Diabetes Association notes that SGLT2 inhibitors are usually held for 3 to 4 days before elective surgery, metformin and other oral diabetes pills are usually held on the day of surgery, and some people are told to take a smaller dose of long-acting insulin the evening before. For GLP-1 medicines, it advises a plan made for you personally (1). Do not change a dose on your own.

If you do not have diabetes

Stress-related high blood sugar is common. In one hospital study, more than 67% of people without diabetes had a reading above 150 mg/dL after major orthopaedic surgery. Their readings peaked about 20 hours after surgery, and more than 87% were back in the normal range after the first 72 hours (2).

That is reassuring, but it is not a reason to ignore it. In the large study above, high readings were linked with more complications in people without diabetes, not less (5). Many hospitals now check blood sugar in all surgical patients and give short-term insulin when needed. If your hospital readings were above 140 mg/dL, ask whether you have had an A1C test in the last 3 months. Diabetes guidelines recommend one in that situation (1), because some people find out about diabetes this way.

What to eat after surgery when blood sugar runs high

Food is one of the few parts of glucose control you run yourself. The goal is steady, not perfect.

1. Eat at regular times. Skipping meals and then eating a large one makes swings more likely, especially if you take insulin or a medicine that can cause lows.
2. Put protein in every meal. Your body needs more protein to repair tissue after surgery. European surgical nutrition experts (ESPEN) estimate about 1.5 g of protein per kg of ideal body weight a day (8). For a 70 kg (154 lb) ideal weight, that is 70 x 1.5 = 105 g a day. Three meals of about 27 g plus one 25 g shake gets you there: 3 x 27 = 81, and 81 + 25 = 106 g.
3. Spread it out. In a small study, eating about 30 g of protein at each of three meals switched on muscle building about 25% more over a day than eating most of it at dinner (9).
4. Keep carbohydrates steady and paired. Eat starches and fruit with a protein food rather than on their own, and keep portions similar from day to day so your readings make sense.
5. Drink water, not juice or soda, unless you are treating a low.
6. Move as soon as you are cleared. Short, gentle walks help your muscles use glucose and support overall recovery.
7. Protect sleep and control pain. Pain, stress and poor sleep raise stress hormones, so following your pain plan and resting well helps keep readings calmer.

If you have kidney disease, ask your doctor before raising your protein. For a full food plan, see our guide on what to eat after surgery.

Practical ways to keep blood sugar steady

Big blood sugar swings can leave you tired and hungry, and around surgery, elevated glucose is linked to slower healing and a higher risk of infection. A few simple habits help. Eat your vegetables and protein before the starches and sweets on your plate. Build breakfast around protein, such as eggs, Greek yogurt or a protein shake, instead of cereal, juice or pastries. If you want something sweet, have it right after a meal rather than on an empty stomach. Pair any carbs with protein, healthy fat or fiber, like nuts with fruit or chicken with pasta. Then take a 10-minute walk after eating, which also helps your recovery. These steps don't require cutting out the foods you enjoy, only changing the order and timing. The one planned exception is the OptiCharge drink the night before surgery, which is meant to give your body fuel going into the operation.

For more simple habits like these, see the 10 Glucose Goddess hacks for steadier blood sugar.

Choosing a protein shake if you have diabetes

A shake can help on days your appetite is low. Read three lines on the label: protein grams, total carbohydrate and added sugar. Aim for a shake that gives a solid serving of protein with modest carbohydrate. As an example, one OptiFuel packet has 25 g of protein and 8 to 9 g of carbohydrate, including 3 g of added sugar (chocolate and vanilla labels). Mixing it with water adds no extra carbohydrate. The first few times you add any new shake, check your blood sugar as your care team advises and write it down.

Can you drink a carb loading drink before surgery if you have diabetes?

Many hospitals now let patients drink a clear carbohydrate drink instead of fasting overnight. In a randomized trial, people who did so felt less hungry and less anxious before surgery (12). In a small hip replacement study, a carbohydrate drink before surgery helped keep more of the body's normal insulin response: insulin sensitivity fell by 18% instead of 43% (13). In a large trial of 880 people without diabetes having major abdominal surgery, only 2.4% of the carbohydrate group needed insulin for high blood sugar afterward, compared with 16.0% of the water group, although infection rates were the same (11).

The picture is less clear with diabetes. A 2020 review of five small trials found pre-surgery carbohydrates probably helpful for people with diabetes, but the quality of the evidence was low (10). European guidelines support the drink to ease discomfort (8). If you have insulin-dependent diabetes or poorly controlled diabetes, check with your care team before using one. For how ERAS teams pair the drink with insulin, see this ERAS study on carbohydrate loading and insulin management in type 2 diabetes (17).

Thrive's OptiCharge has 46 g of carbohydrate (maltodextrin) per packet. The Surgical Protocol Kit plan is 2 packets at bedtime the night before surgery, which is 2 x 46 = 92 g. If you are insulin dependent, skip OptiCharge until your physician approves it. For most people with diabetes, the pre-op drink is fine. If you skip it, the Recovery Protocol Kit is the same OptiFuel without OptiCharge. Our carb loading drink guide covers choosing and timing in more detail.

What to expect: a realistic timeline

Everyone's recovery is different, and the size of your operation matters. This is what the research and guidelines describe for most people.

4 or more weeks before surgery

If you have diabetes, ask when your last A1C was. Guidelines suggest a goal under 8%, measured within the last 3 months (1). If yours is higher, ask your team what they want to see before an elective operation. Start eating protein at every meal now. Our pre-surgery nutrition guide walks through the weeks before.

About 1 week before

Get a written plan for every diabetes medicine. SGLT2 inhibitors are usually stopped 3 to 4 days ahead (1). If your team agrees, this is when you would start one OptiFuel packet a day between meals. In a small knee replacement trial, people who took amino acids starting a week before surgery lost less thigh muscle in the first 6 weeks than people on a placebo (about 6% vs 18%) (14). That trial used a different product and dose, so treat it as a reason to get your protein in, not a promise.

The night before

Follow your team's fasting rules and any insulin change they give you. If you use OptiCharge and have been cleared to, mix each packet with 12 to 16 oz of water and drink both at bedtime. If you take insulin and have not been cleared, skip it.

Day of surgery

Expect a finger-stick check when you arrive. The usual goal is 100 to 180 mg/dL (1). Bring your meter and CGM supplies. If you feel shaky or sweaty while fasting, check your sugar and follow the low blood sugar plan your team gave you.

First 72 hours

A spike is common, with or without diabetes. In people without diabetes, readings peaked about 20 hours after surgery and most were normal again after 72 hours (2). You may be given insulin if readings stay at 180 mg/dL or higher, even if you do not normally use it (1). Restart OptiFuel once you are eating again.

Week 1 at home

Go back to your usual diabetes routine as your discharge papers say. Check your blood sugar as often as you were told, eat on a schedule with protein each time, and look at your incision every day. Call if readings stay higher than your team's limit or you see any warning sign listed below.

Weeks 2 to 6

Your body may still be less sensitive to insulin for up to about 3 weeks after a large operation (3), so readings may run a little above your normal while pain, sleep and activity recover. Keep protein steady, add walking as cleared and log your numbers. This is also when physical therapy picks up, and steady protein supports the muscle you are rebuilding.

After 6 weeks

In studies, insulin sensitivity had returned to normal well before this point (3), so readings should be close to your usual baseline. If they are still higher than normal, see your diabetes provider. If you have no diabetes diagnosis but saw high numbers in the hospital, ask about an A1C test (1).

What using OptiFuel looks like day to day

Take one packet a day between meals, mixed with 12 to 16 oz of water, milk or non-dairy milk. Many people pick a fixed time, such as mid-morning, so it becomes a habit. It is thin enough to drink through a straw. For the first few days, note your blood sugar after you add it and share the log with your care team.

When to call your surgical team

• Redness or pain around the incision that is getting worse, new swelling or bleeding, or a wound that looks larger, deeper, dried out or dark (16).
• Drainage that increases, turns thick, tan, green or yellow, or smells bad (16).
• A temperature above 100°F (37.7°C) for more than 4 hours (16).
• Blood sugar that stays above the limit on your discharge sheet, or high readings with heavy thirst, frequent urination or confusion.
• Blood sugar below 70 mg/dL. The American Diabetes Association's 15/15 rule is to take 15 g of fast-acting carbohydrate, then recheck after 15 minutes (15). Call if lows keep happening, and call 911 if someone cannot swallow safely or will not wake up.

Where Thrive Protocol fits

Each OptiFuel packet gives 25 g of whey protein (non-denatured, gluten-free), 3 g of leucine, glutamine, collagen, omega-3s from fish oil, curcumin, vitamin C, vitamin D and other vitamins. It is made in the USA and Informed Sport tested. No trial has tested OptiFuel itself, and no Thrive product is designed to lower or control blood sugar. Think of it as an easy way to get protein in on days you cannot face a full meal.

• Surgery still ahead: the Surgical Protocol Kit ($299.99 for 4 weeks) pairs daily OptiFuel with 2 OptiCharge packets for bedtime the night before surgery. Start OptiFuel about 1 week before. If you take insulin, check with your physician before using OptiCharge.
• Surgery already done, or skipping the carb drink: the Recovery Protocol Kit ($289 for 4 weeks) is the same OptiFuel without OptiCharge.
• Add-on: the Recovery and Strength Mix ($49.99) is the only Thrive product with creatine and arginine. Thrive suggests taking it daily alongside either kit. If you have kidney disease or reduced kidney function, check with your doctor before using creatine.

Thrive's guidance is that there is no need to stop OptiFuel before surgery because the amounts of fish oil and turmeric are low, but check with your surgeon, especially if you take a blood thinner.

Thrive Protocol kits are HSA/FSA eligible, so you can use pre-tax health dollars.

These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.

The bottom line

Glucose control after surgery matters whether or not you have diabetes. A short rise is normal, but readings that stay high are linked with infections and other complications. Know your numbers, plan your medicines with your team, eat on a schedule with protein at every meal, and call early if something looks wrong. If you have surgery coming up, a conversation about blood sugar with your care team is one of the most useful steps you can take.

Frequently asked questions

Is high blood sugar normal after surgery?

A short rise is common, even without diabetes. In one study, more than 67% of people without diabetes had a reading above 150 mg/dL after major orthopaedic surgery (2). It is caused by stress hormones and a temporary drop in insulin sensitivity. Your team will still treat readings that stay high.

How long does blood sugar stay high after surgery?

In people without diabetes, it usually peaks within the first day and is back in the normal range after about 72 hours (2). The body's insulin response can take up to about 3 weeks to fully recover after a large operation (3), so people with diabetes may see higher numbers than usual for a few weeks.

What A1C is too high for surgery?

The American Diabetes Association recommends an A1C under 8%, checked within 3 months, before elective surgery (1). Your surgeon may use a different cutoff, so ask what they want to see.

Does high blood sugar increase infection risk after surgery?

It is linked with it. In 90,830 hip replacements, a day-of-surgery reading of 277 mg/dL or more with diabetes, or 193 mg/dL or more without diabetes, was linked with higher odds of joint infection (6). CDC guidelines advise keeping glucose under 200 mg/dL during surgery (7).

What should a diabetic eat after surgery?

Regular meals with protein at each one, steady portions of carbohydrate paired with protein, and water instead of sugary drinks. Many people need about 1.5 g of protein per kg of ideal body weight a day around surgery (8). Ask first if you have kidney disease.

Can diabetics drink a carb loading drink before surgery?

For most people with diabetes it is safe, but if you are insulin dependent, check with your physician first. If your diabetes is poorly controlled, check with your care team too (17). A review found it probably helpful for people with diabetes, though the studies were small and low quality (10). If you skip OptiCharge, the Recovery Protocol Kit is the same OptiFuel without the carb drink.

Keep reading

• Pre-surgery nutrition: the 2 to 4 weeks before surgery
• Carb loading before surgery: the simple upgrade
• Top recovery tips for faster healing
• Knee replacement nutrition guide
• Cardiac surgery nutrition guide
• Colorectal surgery recovery nutrition
• Hernia surgery nutrition guide

Getting ready for surgery? See what is inside the Surgical Protocol Kit, built to cover the weeks before and after a procedure.

References

1. American Diabetes Association Professional Practice Committee. 16. Diabetes Care in the Hospital: Standards of Care in Diabetes-2026. Diabetes Care. 2026;49(Suppl 1). PMC12690180 (PubMed 41358892)
2. O'Brien TM, et al. Establishing a recommended duration of blood glucose monitoring in nondiabetic patients following orthopaedic surgery. J Orthop Res. 2022;40(8):1926-1931. PubMed 34674307
3. Thorell A, et al. Insulin resistance after abdominal surgery. Br J Surg. 1994;81(1):59-63. PubMed 8313123
4. Thorell A, Nygren J, Ljungqvist O. Insulin resistance: a marker of surgical stress. Curr Opin Clin Nutr Metab Care. 1999;2(1):69-78. PubMed 10453333
5. Kotagal M, et al. Perioperative hyperglycemia and risk of adverse events among patients with and without diabetes. Ann Surg. 2015;261(1):97-103. PubMed 25133932
6. Wier J, et al. Higher blood glucose levels on the day of surgery are associated with an increased risk of periprosthetic joint infection after total hip arthroplasty. J Bone Joint Surg Am. 2024;106(4):276-287. PubMed 38127864
7. Berrios-Torres SI, et al. Centers for Disease Control and Prevention guideline for the prevention of surgical site infection, 2017. JAMA Surg. 2017;152(8):784-791. PubMed 28467526
8. Weimann A, et al. ESPEN guideline: Clinical nutrition in surgery. Clin Nutr. 2017;36(3):623-650. PubMed 28385477
9. Mamerow MM, et al. Dietary protein distribution positively influences 24-h muscle protein synthesis in healthy adults. J Nutr. 2014;144(6):876-80. PubMed 24477298
10. Ge LN, Wang L, Wang F. Effectiveness and safety of preoperative oral carbohydrates in enhanced recovery after surgery protocols for patients with diabetes mellitus: a systematic review. Biomed Res Int. 2020;2020:5623596. PubMed 32219135
11. Gianotti L, et al. Preoperative oral carbohydrate load versus placebo in major elective abdominal surgery (PROCY): a randomized, placebo-controlled, multicenter, phase III trial. Ann Surg. 2018;267(4):623-630. PubMed 28582271
12. Hausel J, et al. A carbohydrate-rich drink reduces preoperative discomfort in elective surgery patients. Anesth Analg. 2001;93(5):1344-50. PubMed 11682427
13. Soop M, et al. Preoperative oral carbohydrate treatment attenuates immediate postoperative insulin resistance. Am J Physiol Endocrinol Metab. 2001;280(4):E576-83. PubMed 11254464
14. Dreyer HC, et al. Essential amino acid supplementation in patients following total knee arthroplasty. J Clin Invest. 2013;123(11):4654-4666. PubMed 24135139
15. American Diabetes Association. Hypoglycemia (low blood glucose). diabetes.org. Accessed 21 October 2026.
16. MedlinePlus, U.S. National Library of Medicine. Surgical wound care, closed. medlineplus.gov. Accessed 21 October 2026.
17. Bredefeld C, Patel A, Islam S, Peragallo-Dittko V. Enhanced recovery after surgery: Preoperative carbohydrate loading and insulin management in type 2 diabetes. Surg Open Sci. 2024;18:107-110. PMC10920957 (PubMed 38464910)

This article is for education and does not replace advice from your surgeon, diabetes provider or care team. OptiFuel and OptiCharge values are from the product labels.