How To Address Onychomycosis In Patients With Diabetes

Brett Waverly and Kathleen Satterfield, DPM, FACFAOM

The complications of diabetes can desensitize patients to the effects of onychomycosis and complicate management of the condition. Given the increased prevalence of onychomycosis in this patient population, these authors discuss common pathogens and assess the available treatment options.

When is a simple case of onychomycosis not so simple? When it affects a patient with diabetes.

   For many people who entrust their care to a podiatric physician, the complaints that bring them into the office start with concerns with appearance and then grow ­— as the nail grows — to complaints of pain. These patients will seek attention before damage occurs to the underlying nail bed but patients with diabetic peripheral neuropathy are immune to that warning signal, sometimes until it is too late.

   The late Paul Brand, MD, stated that “pain is a gift” because it is the body’s early warning system to help it avoid damage.1 While working in India, he worked with patients who had Hansen’s disease, better known as leprosy, and saw the people around him reaching into flames to retrieve pieces of flat bread to turn them over, never sensing the damage this was doing to their fingers.

   It is the same loss of sensation that, in patients with diabetic peripheral neuropathy, prevents them from feeling the pressure from a tight shoe on the toes. When a thickened nail plate is part of the equation, the pressure on the fragile, vascular rich nail bed occurs with frequency. The result is a subungual ulcer.

   Adding to its “thief in the night” approach is the fact that the ulcer lays covered, unseen beneath the nail plate, growing larger and larger until the toe starts to show signs of its presence. The patients and their caregivers are alerted by signs of infection — purulent material oozing from beneath the nail, erythema and/or bleeding. In 2006, Edmonds and Foster noted that the subungual ulcerations more commonly form in patients with ischemia.2 They advised practitioners to examine toenails “for signs of bruising, bleeding, discharge or other abnormalities.”

Pertinent Insights On Debridement

If the patients are fortunate, one will discover the ulcer at the time of the regular debridement of the nail but this happens if and only if the caseous material of an onychomycotic nail receives aggressive debridement. The physician who decides to limit his or her debridement to the length of the nail and the top several layers of onychomycotic nail may miss the presence of an ulceration completely.

   Another clue to the presence of a subungual ulceration in a patient with diabetes is the presence of hallux limitus with a thickened nail. Boffeli and colleagues found this biomechanical abnormality along with the deforming nail to have caused four ulcers.3

   To discover the subungual ulceration, the podiatric physician must not solely depend on an electronic burr to do the job. He or she must enlist the hand instruments to start eliminating the burden of the nail, piercing into the substance of the nail, above the nail bed and working through the soft underlying material until the bed is visible.

   Of course, this takes time and more confident skills than does the fast pass of a burr.

   Even if a podiatric physician decides to utilize oral or topical pharmaceuticals for treatment, one should still debride the nail burden to allow a better outcome with the medication therapy. The onychomycotic nail is a repository of the fungal elements that are creating and spreading the infection.

Is There Trepidation About Utilizing Oral Antifungals?

With what is known now about oral antifungals, they are the best bet for clinical and microbiological cure widely available.4,5 Still, even with more than a decade of positive outcomes for modern oral antifungals, many podiatric physicians still show a reluctance to give them to any patient, much less a patient with diabetes.


This article should be a wake-up call to those who do not consider oral antifungal meds and who fail to take the time to radically and regularly reduce fungal nails as part of the treatment. When you combine laser for additional therapy and topicals for maintenance, you have the best chance of improvement and ongoing care.

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