This study aimed to determine the prevalence of onychomycosis and interdigital tinea pedis in a cohort of Spanish patients with diabetes in whom onychomycosis was clinically suspected (n = 101). Samples from a first toenail scraping and the fourth toe clefts were subjected to potassium hydroxide direct vision and incubated in Sabouraud and dermatophyte test medium. Fifty-eight samples were also analyzed by a pathologist using periodic acid-Schiff staining and Calcofluor white direct fluorescence microscopy. Onychomycosis was only confirmed in 41 patients (40.6%). Onychomycosis, also known as tinea unguium, is a fungal infection of the nail. Symptoms may include white or yellow nail discoloration, thickening of the nail, and separation of the nail from the nail bed. Toenails or fingernails may be affected, but it is more common for toenails to be affected. The most frequent aetiological agent was Trichophyton rubrum, isolated in 10 patients (36%), followed by Candida parapsilosis in 7 patients (25%). Tests on the fourth toe cleft samples were only positive in 11 patients (10.9%), and in all cases, onychomycosis was also diagnosed. Neuroischemic foot was the only significant variable associated with onychomycosis in the univariate analysis. A positive result for mycosis in the fourth toe cleft was found in 11 cases (10.9%) and was associated with a history of myocardial infarction and neuroischemic foot in the multivariate model. In conclusion, the prevalence of onychomycosis and tinea pedis in patients with diabetes in whom onychomycosis was clinically suspected was 40.6% and 10.9%, respectively. In addition, onychomycosis was not always associated with tinea pedis.
Conclusion: These results show that clinical diagnosis has low accuracy in people with diabetes mellitus, and that diagnosis should not be based on clinical toenail characteristics alone.Onychomycosis might be one of the diagnostic markers for cardiovascular conditions development in diabetes patients, but the mechanism are still unclear.