How To Treat Onychomycosis In Diabetic Patients

By Richard A. Pollak, DPM, MS

Diabetes mellitus is a major health problem in the United States, afflicting approximately 17 million people, with 1 million new cases diagnosed each year in people 20 and older.1 Patients with diabetes are at increased risk for toenail onychomycosis, which can cause discomfort, interfere with mobility, impair quality of life and lead to serious secondary infections and subsequent complications.2 Recent large epidemiological studies have shown the prevalence of onychomycosis in the diabetic population to be as high as 35 percent, compared to estimates ranging from 2 to 13 percent in the general population.3-5 Onychomycosis is a fungal infection that does not remit spontaneously. Over time, it can involve the entire nail unit and spread to other nails, as well as subungual and surrounding periungual tissue and adjacent skin. This compromises the integrity of the skin and may result in secondary bacterial infections and nail bed ulceration.6 Several studies have documented the negative effects of onychomycosis on physical and mental health, physical and social functioning, and physical appearance.7-9 What Are The Consequences Of Not Treating Onychomycosis? There is increasing evidence that onychomycosis is an important medical problem, particularly in the diabetic population. Onychomycosis contributes to the severity of the diabetic foot, especially when it is neglected. Diabetes patients who have peripheral sensory neuropathy and impaired circulation are at an increased risk of developing complications associated with onychomycosis. Predisposing factors such as advanced age, male gender, family history of onychomycosis, concurrent intake of immunosuppressive agents and peripheral vascular disease have been described in the literature.4 Thickened, dystrophic and/or brittle mycotic nails develop that may cause pressure erosions of the nail bed and hyponychium. The nails become sharp and cause injury to the surrounding skin, resulting in the formation of fissures that create a portal of entry for bacteria.3, 11, 12, 13 Unfortunately, the diabetic patient who has sensory neuropathy does not readily notice such breaks in the skin. If the natural course of onychomycosis is permitted to evolve in this setting, the patient may develop a progressive disability, paronychia, nail bed ulceration, cellulitis, serious deep space infections and tissue necrosis.4, 6, 11, 12, 14 Given the proximity of the nail bed to the underlying bone, be aware that neglected, infected nail bed erosion can lead to osteomyelitis among patients with diabetes, necessitating lower limb amputation.12,14 More than 60 percent of non-traumatic lower limb amputations in the United States are performed on patients with diabetes and are typically preceded by a diabetic foot ulcer. 1,15 Retrospective studies by Boyko, et. al., and Doyle, et. al., have evaluated onychomycosis and its impact on the development of secondary infections in patients with diabetes.16,17 Patients with onychomycosis or diabetes were identified from the Clinical Care in America Managed Care Database. Patients with diabetes who had been continually enrolled during 1995 and 1996 were identified in order to calculate the rates of secondary infection. The researchers found a 5.9 percent incidence of onychomycosis among patients with diabetes in contrast to the 0.8 percent incidence rate among non-diabetes patients. They also found that the incidence of secondary infections was higher among patients with onychomycosis and diabetes (16 percent) as opposed to diabetes patients without onychomycosis (6 percent). Furthermore, of 335 patients with diabetes, those with onychomycosis had a higher percentage of gangrene and/or foot ulcer compared to those without onychomycosis (12.2 percent vs. 3.8 percent).16,17 Given that onychomycosis poses a significant risk to the patient with diabetes due to the possible sequelae, effective and aggressive treatment strategies are necessary to prevent such complications.5,18 A Guide To Treatment Options When it comes to managing onychomycosis, the options are similar for treating the condition in diabetes patients as well as non-diabetes patients.

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