Common Cutaneous Findings Associated with Diabetes

Acanthosis nigricans

Acanthosis nigricans is a velvety, hyperpigmented thickening of the skin typically localized around the neck, armpits, and groin areas.¹ It is often one of the first dermatological symptoms of diabetes or metabolic syndrome.¹ Other diseases such as Cushing’s syndrome, Addison's disease, hypothyroidism, acromegaly, hirsutism, obesity, and polycystic ovarian syndrome are also linked to acanthosis nigricans.¹ The underlying disease process or condition needs to be addressed in order to effectively treat acanthosis nigricans.² In type II diabetes, metformin or other insulin-regulating medications can address the underlying insulin resistance.² Common topical treatments that address the cosmetic concerns of acanthosis nigricans include retinoids, vitamin D, and chemical peels.²

Acanthosis nigricans on the ankle (Zufall)³

Diabetic dermopathy

Diabetic dermopathy is the most common skin condition in individuals with diabetes.⁴ It is often seen early and thus can lead to a prompt diagnosis of diabetes, which can prevent or delay serious diabetic complications such as retinopathy, neuropathy, and nephropathy.^5,6 Diabetic dermopathy is associated with an increased risk of cardiovascular disease.^6,7 Diabetic dermopathy presents as atrophic, hyperpigmented macules commonly found on the shins.⁶ They are typically found over bony prominences, although it is unclear whether or not diabetic dermopathy lesions are caused by trauma.⁴ The lesions are usually not itchy or painful.⁴ It is more commonly found in men.⁴ There is currently no effective treatment for diabetic dermopathy.⁸

Fungal infections (Candida albicans)

Patients with diabetes are at an increased risk of fungal infections from Candida or dermatophytes.⁹ The most common fungal infections include tinea pedis, onychomycosis, candidal intertrigo, and candidal vaginitis.⁹ It is important that fungal infections are treated in order to prevent a potential entry point for pathogenic bacteria.⁹ Treatment of candida infections include topicals with nystatin, clotrimazole, or econazole.⁹ Oral antifungals, such as fluconazole, can be used if topical antifungals are ineffective in treating the infection.⁹

Bacterial infections

Cutaneous bacterial infections can manifest in several different ways in individuals with diabetes. One of the most common bacterial skin infections is known as diabetic foot syndrome. Diabetic foot syndrome is an ulceration of the foot caused by diabetic peripheral neuropathy and peripheral vascular disease.¹⁰ Longstanding and uncontrolled hyperglycemia can potentiate the onset of peripheral neuropathy, which then increases the risk of diabetic foot syndrome.¹⁰ Peripheral neuropathy starts distally and progresses proximally over time, oftentimes unknowingly to the patient since the neuropathy leads to loss of sensation in the feet. Small injuries to the feet may go unrecognized and untreated, ultimately leading to ulceration or gangrene.^10,11 The most common bacteria for diabetic infections are S. aureus, E. coli, and S. epidermidis.¹¹

Prevention plays a critical role in diabetic foot syndrome. It is important that individuals with diabetes have their feet checked annually by a primary care provider or a podiatrist.¹⁰ Additionally, these healthcare practitioners can educate patients on foot care and proper footwear.¹⁰ Treatment of diabetic foot syndrome includes topical approaches such as wet to dry dressings, topical antibiotics, polyurethane dressings, and hydrogel dressings.¹⁰ The use of oral antibiotics in diabetic foot syndrome is essential in reducing morbidity.²³ In addition to conventional wound care, hyperbaric oxygen therapy has increased the healing rate of diabetic foot ulcers, shortened healing time, and reduced the incidence of major amputation compared to treatment with wound care alone.^20,21 If dressings, antibiotics, and hyperbaric oxygen therapy are ineffective, the ulcerated digits or entire extremity may require amputation.¹¹

Diabetic foot syndrome (Amin)¹⁰

Other common diabetic skin infections are erysipelas and cellulitis. Erysipelas is a painful superficial cellulitis localized to the top layers of the skin.¹² Cellulitis is a bacterial infection that goes beyond the superficial layers of the skin and is associated with pain and erythema that is more diffuse.¹²

Diabetic blisters (bullosis diabeticorum)

Bullosis diabeticorum, also known as diabetic blisters, are a less common dermatological manifestation found in patients with long-standing diabetes.⁴ They occur more often in men. These are non-inflammatory and asymptomatic blisters typically affecting the extremities, mostly the legs and feet.⁴ The blisters may range in size from 0.5 cm to 5 cm and usually contain clear non-serous fluid.⁴ The condition is often misdiagnosed because it can mimic other bullous disorders.¹³ Treatment of bullosis diabeticorum may include draining the fluid of the blister with a needle and maintaining the skin surrounding the blister in order to prevent infection.¹³

Balanitis

Balanitis is a common condition characterized by inflammation of the glans of the penis. A related condition called balanoposthitis occurs exclusively in uncircumcised males and includes the foreskin in addition to the glans of the penis. Patients with balanitis or balanoposthitis will present with penile pain and redness. Recurrent balanitis is associated with poorly controlled diabetes. The inflammation can be caused by fungi, bacteria, or viruses.¹⁴

The most common cause of balanitis is Candida albicans, which thrives in the warm and moist microenvironment under the foreskin. C. albicans is also the most common cause of balanitis in patients with diabetes. Prevention primarily involves proper hygiene, and treatment includes topical antifungals such as imidazoles.¹⁴

Necrobiosis Lipoidica Diabeticorum (NL)

Necrobiosis Lipoidica (NL) is a granulomatous dermatitis that may be seen in individuals with diabetes. NL is no longer considered a primarily diabetic skin condition and is rarely seen in individuals with diabetes, with estimates of the prevalence of NL among patients with diabetes ranging from 0.3 to 1.2 percent.²² Additionally, many other systemic associations such as Crohn’s disease, ulcerative colitis, rheumatoid arthritis, sarcoidosis, and thyroid disorders are associated with NL. NL presents as atrophic plaques on the lower extremities, most commonly the shins. The lesions will begin as small erythematous papules then slowly expand with central atrophy. Although the etiology is unknown, common theories suggest vascular disturbances due to immune complex deposition or collagen-altering immune responses. Blood glucose control does not seem to be helpful in the treatment of NL. Although NL is typically self-limiting, additional treatments may be recommended, although these are often ineffective. Compression therapy may be used for those with NL and venous disease or lymphedema. In patients with ulcerations present, wound care should be utilized. Monoclonal antibodies and topical calcineurin inhibitors such as tacrolimus have been effective therapy in ulcerating NL. Potent topical corticosteroids may be used for early lesions and intralesional corticosteroids injections into the borders of established lesions. UV light therapy may be effective. Antiplatelet aggregation therapy such as dipyridamole and aspirin may help; one potential mechanism of NL development is platelet-mediated vascular occlusion.¹⁵

Vitiligo

Vitiligo is caused by an autoimmune attack on melanocytes.¹⁶ Clinically, white, depigmented spots and patches appear on the body, typically distributed symmetrically. It can be more distinct in people with darker skin tones.¹⁷ Vitiligo occurs in patients with type I and type 2 diabetes.^18,19 Vitiligo may appear at the onset of diabetes and can allow an early diagnosis of diabetes. Treatment of vitiligo includes topical and systemic medications and phototherapy.¹⁷

Key Takeaways

1. Individuals with diabetes are at an increased risk for skin diseases
2. Diabetic management and glycemic control will often improve some, but not all, dermatological manifestations of diabetes
3. Diabetic skin diseases may mimic other cutaneous conditions and correct diagnosis is key to proper treatment