Smoking, Diabetes and Foot Surgery Healing: What to Know

Surgeons do not ask about smoking and blood sugar to judge you. They ask because these are two of the biggest risks for a wound that will not close or a bone that will not knit, and, unlike your age or the shape of your foot, they can sometimes be changed. This article explains what the research shows, what is and is not settled, and what you can do. It builds on our checklist for how to prepare for foot and ankle surgery.

Why the foot heals differently

Healing depends on a good supply of oxygen-rich blood, and both smoking and diabetes work against it. Nicotine and carbon monoxide constrict the small blood vessels and reduce oxygen delivery to tissue.^[1] Diabetes can damage the nerves in the feet, so injuries and pressure go unnoticed, and it can narrow the arteries of the legs, so less blood reaches a wound to heal it.^[3]

What the research shows about smoking

A systematic review of the effect of smoking on wound and bone healing in foot and ankle surgery found that smoking, including smokeless tobacco, significantly increases the risk of complications. Smokers showed markedly higher rates of nonunion, wound infection and delayed bone healing than non-smokers. In the studies reviewed, smokers had a 14.8% wound infection rate, and 14.5% of smokers had non-union or malunion, compared with 6.7% of non-smokers. Elective procedures such as total ankle replacement also did worse in smokers. The review reported that stopping smoking before surgery was linked to lower infection rates and better healing.^[1]

One caution: the review was small, based on six articles selected from 28 screened, including retrospective studies. It shows a consistent direction of risk, but the exact percentages should be read loosely.^[1]

What the research shows about diabetes

It is not simply “diabetes or no diabetes.” The studies point to nerve damage and other complications, and to blood sugar control, as the main drivers.

• Nerve damage matters more than the label. In the 1,465-operation study, peripheral neuropathy, Charcot neuroarthropathy, current or past smoking and longer operations were each associated with infection, and the authors concluded that it is neuropathy, not diabetes itself, that most strongly determines postoperative infection.^[2]
• Complications of diabetes raise the risk. In the 2,060-operation study, people with complicated diabetes had a 7.25-fold higher risk than people without diabetes or neuropathy. People with uncomplicated diabetes did not differ significantly from those without diabetes. Nerve damage without diabetes raised the risk 4.72-fold, and both neuropathy and a hemoglobin A1c of 8% or more were independently associated with infection.^[4]
• Blood sugar counts, but it is one factor among several. In the Veterans Affairs database, the overall 30-day complication rate was 3.2%. Each 1% rise in hemoglobin A1c raised the odds of a complication by 5%, having neuropathy raised the risk 1.78 times, and having two or three diabetes-related conditions raised it 3.08 times. The authors noted that complication rates are multifactorial.^[5]

What you can do before an elective operation

If you smoke: ask us for help to stop. The review called preoperative counseling and smoking cessation programs crucial for optimizing outcomes.^[1] This includes smokeless tobacco. The review called for more research on newer tobacco alternatives, so ask your team about them instead of assuming they are safe for healing.

If you have diabetes: know your recent hemoglobin A1c, and involve your diabetes doctor. Your surgical team may ask you to improve control before an elective operation, and it will look at nerve health and circulation too. There is no single cutoff that fits everyone: one study linked an A1c of 8% or more with infection,^[4] and another found the risk rose steadily with each percentage point,^[5] so your team weighs the number against the operation and everything else about you.

If you have numb feet: tell us. Reduced sensation means a problem on the foot can go unnoticed, and regular foot checks and proper footwear are part of preventing ulcers.^[6] See diabetic foot ulcers and Charcot foot.

For everyone: good nutrition, controlled blood pressure and healthy skin all support healing. See preparing for foot and ankle surgery.

When surgery cannot wait

Not every operation is elective. Infections and abscesses in the diabetic foot need urgent surgical attention, and an urgent operation is planned around your condition.^[7] Do not delay care for a foot problem while you try to improve your numbers.

After surgery

Healing continues to depend on the same things. Follow your weight-bearing plan, keep the foot elevated, and keep to your medicine schedule. If your feet are numb, look at them every day; a wound can appear without pain.^[6] The signs of a problem are a sore or crack that is not healing, redness, warmth or swelling, drainage or a bad smell, skin that is pale, blue or cold, and fever.^[3,7] The bunion surgery recovery timeline shows how recovery usually unfolds.

Questions to ask your surgeon

• How do my smoking and diabetes change the risks of this operation?
• Should anything be improved first, and by when?
• Do you want a recent hemoglobin A1c, and from whom?
• Is my nerve health or circulation a concern?
• Does this operation carry more risk for me than a different one?

Common questions

Can I have foot surgery if I have diabetes?

Yes. The studies above include many people with diabetes who had foot and ankle surgery, and the risk depended more on nerve damage, complications and control than on the diagnosis alone.^[4,2]

How long before surgery should I stop smoking?

Sooner is better. The review linked stopping before surgery to fewer infections and better healing, but it does not settle a specific number of weeks, so your surgical team will advise you.^[1]

What A1c do I need?

There is no single number for every person or operation. An A1c of 8% or more was associated with infection in one study, and each 1% rise raised the odds of a complication in another. Your team decides.^[4,5]

I have neuropathy but not diabetes. Does it matter?

Yes. In one study, people with neuropathy but no diabetes had 4.72 times the risk of infection compared with people with neither.^[4]

Do vaping and nicotine patches count?

The review looked at cigarettes and smokeless tobacco and called for more research on newer tobacco alternatives. Ask your surgical team.^[1]

The bottom line

Smoking and diabetes complications, nerve damage above all, raise the risk of infection and slow healing. Neither rules out surgery, and both can often be improved beforehand. Tell your surgeon the whole picture, work on what you can change, and never delay care for an infected or badly wounded foot.