Title : Emerging mycotic nail infections (onychomycoses) among diabetic patients
Abstract:
Diabetes, Diabetes Mellitus (DM) or high blood sugar (or hyperglycaemia) is a life-style based metabolic disorder that increases the risk of heart disease, kidney, nerve damage, and fatty liver disease, causing globally 1.5 million deaths each year. As per the latest International Diabetes Federation (IDF Atlas, 2025), Type 2 diabetes (T2D) is a worsening global epidemic with nearly 600 million adults living with diabetes, and over 4% are unaware that they are diabetics, their number is projected to reach 853 million by 2050. Even T2D is increasing in children and adolescents, especially in the US, where the number could jump from 28000 in 2017 to a staggering 2,20,000 by 2060 (CDC, 2025). Prandial glucose is used as a parameter to define diabetics. As per the American Diabetes Association (ADA) and CDC, diabetic patient refers to a person with blood sugar levels > 126mg/dL (Pre-prandial, fasting), > 180 mg/dL (Postprandial, after meal), and Hb1Ac > 7% (2-3 months average).
Globally, between 200 and 300 fungi, of the 1,60,000 currently described taxon, are known to infect and cause mild to severe human diseases, called mycoses. Over 1 billion people get a fungal infection each year. Mycoses are very common, especially superficial one’s affecting skin, hair and nails, with estimates suggesting 20-25% of people worldwide have them. Sever systemic (deep) infections are rising due to immunosuppression from conditions like diabetes, HIV/AIDS, cancer, transplants, COVID-19, and using steroids. Life-threatening mycoses cause 2.5 million deaths of the 6.5 million individuals affected annually, 6.7% of the total 55 million deaths recorded worldwide, surpassing the impact of four fatal diseases like tuberculosis, malaria, hepatitis and pneumonia. Fungal infections disproportionately impact immunocompromised populations, making them a significant global health problem due to alarming rise in diabetes, limited treatments and drug-resistant strains. Hyperglycaemia weakens the host's immune system making them more susceptible to mycoses. The World Health Organization (WHO) in 2022 has identified 19 fungal pathogens that have been put in the Priority Pathogens List to tackle the growing global threat of fungal infections.
Onychomycosis is amongst the most common nail disorders impacting an estimated 4-5% of people worldwide. Amongst diabetics, the prevalence of onychomycosis is 3 times higher than the non-diabetics, and is associated with an elevated risk of secondary bacterial and fungal infections with severe complications like cellulitis, ulcers and even amputation due to poor healing as blood flow is very slow in them. Based upon the initiation of infection on toenails, onychomycosis is categorized into 5 types: distal subungual (under nail), white superficial (top surface), proximal subungual (near cuticle), endonyx (within nail plate) and total dystrophic (severe, end stage). In addition, mixed patterns affecting nail colour, texture and adherence also occur. Distal subungual onychomycosis (DSO) which affects the nail bed and plate is most common worldwide. Clinically nails have yellow, or brown discoloration, thickening and distortion, longitudinal yellow stripes, and separation of the nail from nail bed (called onycholysis), including pain/ discomfort, especially with toenails affecting walking.
Onychomycosis is caused by the dermatophytes (called tinea unguium), yeasts (candidal onychomycosis) and saprophytic molds. The dermatophytes caused over 90% infections, Trichophyton rubrum is most common and frequent, but other dermatophytes such as Trichophyton mentagrophytes and Epidermophyton floccosum, can also cause it. Candida albicans is involved in 2% cases of onychomycosis, especially in fingernails, diabetic patients are more vulnerable to infections involving species of Candida. Non-dermophytic saprophytic molds (Fusarium, Aspergillus, Acremonium, Scytalidium and Scopulariopsis brevicaulis) cause 8% nail infections.
Onychomycosis is diagnosed mainly by microscopic observations of KOH preparation. Fungal culturing is used to specify the infection's cause (species identification), including susceptibility to antifungal drugs. Presence and absence of microconidia, shape, septation, rough or smooth-walled, and mode of production on conidiophore, are used for identifying dermatophytes. PCR is used, especially for confirmation of species identity, only in severe cases. Managing diabetes requires stable blood glucose levels to prevent serious health problems by avoiding all forms of added sugar (white sugar, brown sugar, honey, honey and jaggery/ Gur), and relying on whole hygienic foods, fruits, healthy cooking habits, walking/ exercise, including antidiabetic medicine. Diabetes in teens can be managed through a recently introduced Eli Lilly’s drug Mountjaro, which reduces blood sugar levels as well as the weight loss.
Onychomycosis is treated with topical agents, periodic debridement and systemic antifungals. Mild or moderate infections of nails can be treated with topical antifungals like ciclopirox lacquer (nail polish), efinaconazole solution and tavaborole solution. Severe onychomycosis, especially among diabetic patients which have a higher risk of diabetic foot ulcers should be treated by oral terbinafine, itraconazole or fluconazole, having the cure efficacy 76%,63% and 48%, respectively.
