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December 12, 2025The skin serves as a “window” to many systemic diseases, and recognizing the dermatological manifestations of these conditions can accelerate correct diagnosis and timely treatment initiation.
Among the diseases that can manifest on the skin is diabetes mellitus. When certain characteristic skin lesions appear, it indicates that the person either has undiagnosed prediabetes or diabetes, or that their antidiabetic treatment needs adjustment because their blood sugar remains uncontrolled.
“Possible lesions are many and diverse, but their appearance requires evaluation by a doctor,” emphasizes dermatologist and venereologist Dr. Markos Michelakis, from EDOEAP.
It is estimated that up to 50% of patients with type 1 or type 2 diabetes develop skin complications at some point during the course of their disease. “These dermatological conditions may be benign, cause skin deformity, or, more rarely, threaten life,” explains Dr. Michelakis. “In any case, they indicate glycemic control, that is, how well the patient regulates blood glucose levels. They may also be the first sign of glycemic dysregulation. Early recognition and management are important to maintain the quality of life of patients and to prevent serious adverse effects of diabetes.”
The most common skin manifestation caused by diabetes is the so-called diabetic dermopathy. It is characterized by small, dark patches or, less frequently, lines, usually appearing on the shins of patients. Rarely, they appear on the arms, thighs, torso, or other areas of the body. They are due to damage caused by diabetes to the blood vessels. When oval-shaped, they resemble age spots. Unlike age spots, however, they may disappear within 18–24 months.
Another frequent complication is diabetic thick skin. Affected areas may show thickening, waxy texture, or swelling (edema). Patients may be asymptomatic or experience reduced sensitivity and pain. While it can occur in various parts of the body, thickening is most commonly observed on the dorsal hands and feet.
In patients with type 1 diabetes or long-standing disease, thickening resembles scleroderma, causing hardening of the skin and giving it a waxy appearance. Scleroderma-like skin changes develop gradually, symmetrically, and bilaterally in certain parts of the extremities, mainly on the dorsal surface of the fingers (sclerodactyly) and on the skin above their joints. In more severe cases, these lesions affect the arms or back.
It is common for diabetic patients, especially elderly type 2 patients, to develop asymptomatic yellow discoloration of the skin or nails. These benign changes are usually observed on the palms, soles, face, or the toenail of the big toe. The pathogenesis of this phenomenon remains unclear. Discoloration has been observed in up to 50% of diabetic patients.
Another common dermatological manifestation of diabetes is acanthosis nigricans. Patients present a darkened area on the skin, usually in areas where folds form, such as the sides of the neck, armpits, groin, or other areas. This area resembles velvet and indicates elevated insulin levels in the body. Acanthosis nigricans is more common in obese individuals with prediabetes and patients with type 2 diabetes. It is also more common in people with darker skin.
Necrobiosis lipoidica is a deforming but fortunately rarer skin complication of diabetes, affecting less than 1% of patients. Small papules appear on the skin of the legs, quickly turning into hard, raised plaques with yellow-orange coloration. These plaques mainly develop on the shins of both legs. Occasionally, they develop in other areas of the body. Blood vessels are visible on their surface, and they may cause itching and, in some cases, painful ulcers. Necrobiosis lipoidica occurs in cycles of flares and remissions.
Another rarer skin manifestation in diabetic patients is blisters filled with clear fluid, which may be solitary or grouped. Scientifically, these are called diabetic bullae (bullosis diabetricorum) and mainly develop on the hands and feet. Although they can appear early in diabetes, they usually manifest in long-standing disease alongside other complications such as diabetic neuropathy and nephropathy. They are also more common in type 1 diabetes patients. Diabetic bullae resemble blisters formed after burns but are painless. They usually resolve with proper care without leaving scars.
“The potential skin complications of diabetes do not end with the aforementioned,” emphasizes Dr. Michelakis. “Patients are also prone to persistent skin infections and fungal infections, severe dryness, even impaired wound healing which can lead to life-threatening complications like diabetic foot. They may also develop various types of rashes and other skin lesions and may experience worsening of existing skin conditions such as acne, eczema, and psoriasis.”
Most skin complications of diabetes are not life-threatening and can be treated with appropriate medical care. However, the most effective treatment is good glycemic control, stresses the specialist. “If blood sugar levels are well regulated, managing skin conditions becomes easier,” he explains. “Otherwise, persistently high blood sugar will hinder the effectiveness of any skin treatment.”
https://www.ncbi.nlm.nih.gov/books/NBK481900/
https://www.aad.org/public/diseases/a-z/diabetes-warning-signs
