Black Toenail Diabetes: Complications & 3 Effective Treatments

Naturally, our toenails are white in color, but certain conditions like diabetes could lead to the discoloration of toenails, this situation is called “Black Toenail Diabetes”. Other factors are trauma, nail polish, nutritional deficiencies, or infections. Most times this discoloration may resolve on its own. If your toenail doesn’t get better after some time, you should check with your doctor to rule out more serious causes of a black toenail, such as diabetes.


A black toenail can be as a result of any of these:

Trauma: Trauma to the toenail, usually caused by an injury, can cause the blood vessels beneath the nail to break. The resulting bleeding of these blood vessels makes the toenail to appear black.

Malignant Melanoma: This is a serious skin condition. It is a type of skin cancer that can develop under the fingernail or toenail, causing hyperpigmentation in the nail plates. It is a painless condition that could go undetected and gradually spreads until you notice the discoloration on your nail plate. A biopsy is usually recommended to diagnose the disease and suggest treatment accordingly.

Fungal Infection: Fungal infection in the nail is caused by a group of fungi that thrives on keratin and moisture. They are known as dermatophytes. Although this infection in the nail often appears white or yellow, it can also sometimes cause black toenails from the buildup of debris in the nail.

An Underlying Medical Condition: A black toenail can develop if you have any of these underlying medical conditions:

  • Anemia
  • Heart disease
  • Psoriasis
  • Lichen planus
  • Kidney problems
  • Diabetes

Any of these medical conditions can cause you to have a black toenail.


There are several ways diabetes affects general health. Talking about the toenails, there are a lot of changes that happen there when a person is diabetic, and these changes are due to poor blood circulation, trauma (which often goes unnoticed due to neuropathy), and high blood sugar.

Toenail discoloration due to diabetes usually starts from the tip of the nail and runs down to the nail bed. The discoloration is usually the first thing you will notice in a diabetic’s toenails’ it could be yellow, brown-tinged, canary yellow, or even black.

Apart from nail discoloration, here are some other ways diabetes affects the nails:

Onychauxis: This is a condition that results from the natural process of aging, but at the same time is a common symptom of diabetes. It is the thickening or hypertrophy of the nail of the nail plate of the toenail, which typically includes discoloration.

Onychocrytosis: It is also known as ingrown toenail, meaning that the nail grows into the subcutaneous tissue along the sides of the nail, instead of growing outwards. Although some other causes such as wearing ill-fitted shoes, improper cutting of the nails, or previous trauma could trigger this condition, diabetes is also a causing factor.

In a non-diabetic, this condition can be extremely painful, but in a diabetic, due to peripheral neuropathy that can inhibit the sense of feeling, they may not notice as the condition progresses.

Onychogryphosis: Also known as Ram’s Horn, it is the thickening of the base of the toenail which could cause severe deformity and make the nail appear very curved or hooked. It is often caused by infrequent nail-cutting which is common among diabetics who are often scared of trimming their nails or embarrassed to seek professional help in doing that.

Onychomycosis This is a term for a fungal infection on any part of the nail, and diabetics are more susceptible to this condition. At the onset, it begins with discoloration, but if left untreated it progresses to cause pain, loss of dexterity, and numbness. Ultimately it can interfere with the way you walk or stand.

Pincer or Trumpet Nail: This is an extreme curvature that appears like a cone or a trumpet formation, hence the name. it causes skin breakdown and can lead to ulceration. Unless neuropathy sets in, it can be extremely painful for diabetics.


As the name “Black Toenail Diabetes” We have seen that diabetes can lead to discoloration of the toenail. Black toenail diabetes is often due to the collection of blood under the nail, which may result from acute or chronic trauma.

Diabetes causes a restriction in the supply of blood, and like other tissues of the body, the nail needs an adequate supply of blood. A reduced supply of blood to the nail can make it appear thin and brittle and lead to the split or breaking of the nail, contributing to the black discoloration of the toenail and facilitating infection.  Black toenails in diabetes can occur when the foot is lacking in the supply of oxygenated blood and nutrients. With no blood circulation, the nail dies, hence, black toenail diabetes.


If you are diabetic, it is important to get your doctor to examine your black toenail because if left unattended to, it may lead to complications such as neurotrophic ulceration.

Neurotrophic Ulceration

About 25% of the diabetic population has at least one-foot ulceration during their lifetime. The change in blood and nutrient supply to the toenail can lead to its ulceration, and this can be traced back to neuropathy. Neurotrophic ulcers do not cause pain, but if not treated immediately, could cause serious damage.


Treatment of black toenails in diabetes would require the care of a specialist called a podiatrist. Podiatrists are doctors who specialize in the feet. Treatment depends on how severe the condition has become. It may include:

  • Draining fluid or pus if it has resulted in an ulcer
  • Removing or cutting away dead or infected tissues due to poor circulation of blood
  • Prescribing oral IV or antibiotics to control and eliminate infection


Most times the appearance of a black line on the nail is not a sign of something serious to get you worried, but it is still advised to get it checked because if the appearance of the black line persists for more than a few days, it could be indicating an underlying condition.

Splinter hemorrhages are tiny blood spots that appear underneath the nail. They look like a vertical line running down one of your fingernails. It can be caused by trauma, fungal infection, bacterial endocarditis, vasculitis, high cholesterol levels, melanoma, and diabetes.

Since high blood sugar causes blood vessels to damage, one of these blood vessels can splinter, causing a hemorrhage that forms the black line on the nail. This is most common in patients with Type 2 diabetes.


Diabetes can cause nail discoloration, in some cases, this discoloration is not black, just like the one we’ve talked about in this article. Instead, it takes a yellow hue. This however is a sign of nail infection. People with diabetes are more prone to get a fungal infection known as Onychomycosis. This infection usually affects the toenails, making them appear yellow and brittle.

It can be treated with the use of an antifungal cream or an antifungal drug such as Lamisil or Sporanox, which are considered safe for diabetic patients. However, if the infection is severe, it might require a podiatrist to remove the affected toenail.


Black toenail is often caused by trauma and should disappear after a few days, but when it doesn’t you should seek medical attention as it might be an indication of an underlying condition such as diabetes.

Diabetes leads to the damage of blood vessels, and when these blood vessels are damaged, blood, oxygen, and nutrient supply to the toenail become restricted. This causes the death of the tissue in the nail, hence resulting in the black discoloration of the toenail affected.

Diabetes can affect the nails in so many ways, and if not treated immediately, could lead to complications that in some cases require the amputation of the affected toenail.

Diabetics should regularly check their toenails for any discoloration and report back to their doctors immediately.


  • Can Diabetes Cause Toenail to Turn Black?
  • Diabetic Toenails: Watch For Change.
  • Nails in Diabetes.
  • The Black Line on Nail: Is It Splinter Hemorrhages?
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