Toenail Fungus and Diabetes: Why It Matters

For many people, toenail fungus is mostly an annoyance: unsightly, slow to clear, but not dangerous. If you live with diabetes, it's worth taking more seriously. This isn't meant to alarm you. It's about understanding why your feet need a little extra care, and why the best first step is to involve your healthcare team early.

Why diabetes and toenail fungus are linked

The American Academy of Dermatology (AAD) and the Canadian Dermatology Association both list diabetes among the risk factors for fungal nail infection. Several things may play a part:

• Circulation. Diabetes can reduce blood flow to the legs and feet, which can affect how well the body fights infection and how quickly nails grow.
• Immune response. High blood sugar over time can make it harder for the body to fight off infections.
• Nail and skin changes. Thicker nails, dry or cracked skin, and small injuries can give fungi a way in.

Why it matters more when you have diabetes

Diabetes Canada explains that diabetes can cause nerve damage (peripheral neuropathy) and poor circulation in the feet. As a result, people with diabetes are less likely to feel a minor injury, such as a blister or cut, and those injuries can be slower to heal and more likely to become infected.

A fungal toenail fits into that picture in a few ways:

• Thick, sharp or lifting nails can press on or cut the surrounding skin, sometimes without you feeling it.
• Breaks in the skin around an infected nail, or athlete's foot cracks between the toes, can let bacteria in. Mayo Clinic notes that nail fungus may lead to other serious infections that spread beyond the feet in people whose immune system is weakened by medication, diabetes or other conditions.
• Thick nails are harder to trim safely, raising the risk of nicks and ingrown nails.

The NHS specifically advises people with diabetes to see a GP about a fungal nail infection, because foot problems can be more serious with diabetes. Mayo Clinic likewise suggests talking to a healthcare provider if you have diabetes and think you're developing nail fungus.

Signs to watch for

Check your feet every day, as Diabetes Canada recommends. Look for:

• A toenail that's thickening, turning white, yellow or brown, crumbling or lifting.
• Itchy, peeling or cracked skin between the toes (possible athlete's foot).
• Redness, warmth or swelling around a nail.
• Pus, drainage, or a sore that isn't healing.
• Any change in the colour of your foot, or new pain.

Use a mirror to see the bottoms of your feet, or ask someone to help. Wearing white socks can make drainage from a cut easier to spot.

Safe foot care habits

These come from Diabetes Canada's foot care guidance and general advice from dermatology organizations:

• Wash and dry your feet every day, especially between the toes.
• Don't soak your feet. Diabetes Canada lists soaking among the things to avoid.
• Moisturize heels and soles, but not between the toes.
• Trim nails straight across and file sharp edges. If your nails are thick or hard to reach, have a foot care professional do it.
• Wear clean socks and well-fitting, supportive shoes every day.
• Don't walk barefoot, indoors or out.
• Don't cut corns, calluses or ingrown nails yourself, and avoid over-the-counter corn and wart treatments unless your provider says otherwise.

Why you should be cautious with home and pharmacy treatments

Online remedies often involve soaking, filing, or applying acids, essential oils or other strong ingredients, all of which can damage skin that may heal slowly. Even some over-the-counter foot products aren't recommended for people with diabetes. Talk to your healthcare provider before trying anything. Our articles on home remedies and over-the-counter products explain what the evidence says.

Confirming the cause matters even more

Many thick, discoloured nails aren't fungal. Shoe pressure, old injuries and other conditions can look the same (see toenail fungus or nail trauma?). For people with diabetes, knowing the cause helps your healthcare team choose the right approach, and avoids months of treatment that can't help. Prescription antifungals also need to be weighed against your other medications and health conditions, which is one reason providers often want confirmation first.

A qPCR DNA test of a nail clipping can show whether fungal DNA is present. Bring the result to your appointment as one more piece of information, not as a substitute for being seen.

Testing safely if you have diabetes

Our at-home kit includes a nail clipper, alcohol swab, sample pouch and prepaid return envelope. If you have diabetes, take extra care when collecting your sample:

• Only clip nail that extends beyond the skin; never cut close to or into the skin.
• If your nails are thick, hard to reach, or you have reduced feeling in your feet, ask a podiatrist, chiropodist or other foot care professional to collect the clipping for you.
• If you nick the skin, clean it with mild soap and water, cover it, and watch it closely. Contact your healthcare provider if it doesn't heal or looks infected.

Every result is reviewed by a licensed Canadian podiatrist with over 50 years of experience, and your report arrives 4–14 days after your sample reaches us. See a sample report and our guide to understanding your results, then share your report with your diabetes care team.

Frequently asked questions

Is toenail fungus dangerous for people with diabetes?

It can be more serious. Diabetes can reduce feeling and blood flow in the feet, so small breaks in the skin around a thick or infected nail may go unnoticed and heal slowly. That raises the risk of other infections. People with diabetes should see a healthcare provider about any nail change.

Can I treat toenail fungus myself if I have diabetes?

It's best not to. Diabetes Canada advises against treating some foot problems yourself and against soaking your feet. Talk to your doctor, nurse practitioner, podiatrist or chiropodist before using any home remedy or pharmacy product.

Who should trim my toenails if I have diabetes and thick nails?

A podiatrist, chiropodist or trained foot care nurse can safely trim and thin thick nails. Ask your healthcare provider for a referral or recommendation.

Does diabetes make toenail fungus harder to treat?

Diabetes is a risk factor for nail fungus, and slower nail growth or circulation problems can make treatment take longer. Your healthcare provider will consider your diabetes and other medications when discussing options.

Can I use an at-home nail fungus test if I have diabetes?

Yes, as long as you can collect the sample safely. Only clip nail that extends past the skin, and ask a foot care professional to collect it if your nails are thick or you have reduced feeling. Share the result with your healthcare team.

Sources

• Diabetes Canada: Diabetes and foot care checklist
• Diabetes Canada: Foot care, a step toward good health (PDF)
• U.S. National Institute of Diabetes and Digestive and Kidney Diseases: Diabetes and foot problems
• American Academy of Dermatology: Nail fungus, causes
• Canadian Dermatology Association: Nail fungus and infection
• NHS: Fungal nail infection
• Mayo Clinic: Nail fungus, symptoms and causes