Skin changes occur in up to 80 percent of people with diabetes, and not only in a late stage of the disease, but certainly already at elevated blood glucose levels in the prediabetic stage. Poor metabolic control promotes pathological skin changes. Poorly controlled diabetes can be the cause of skin complaints such as severe itching, blistering, redness, wrinkles or boils. People with diabetes should therefore strive for the best possible metabolic control and take care of their sensitive skin.
If metabolism is well controlled, people with diabetes are no more susceptible to fungal and other skin infections than healthy individuals. However, about one third of them suffer from skin dysfunctions due to high blood sugar levels.
A variety of mechanisms are involved in the development of skin diseases in people with diabetes. The processes have not yet been elucidated in detail for all clinical pictures. However, some skin diseases show a direct correlation to elevated blood glucose levels and their consequences.
– In the case of an insulin deficiency or insulin resistance, the body excretes more fluid through the urine. The body loses water in the process. The skin becomes dry. – Sebaceous and sweat glands of the skin produce less oil and moisture due to nerve damage. This causes the skin to dry out considerably. The skin becomes itchy, scaly, cracked and loses its protective function. Pathogens can penetrate and multiply more easily. At the same time, particularly in the case of poorly controlled diabetes, there is an immune deficiency that allows infection to occur and can lead to rapid spread of the disease. The yeast infection thrush, for example, occurs more frequently in people with diabetes. It is manifested by whitish coatings on the oral mucosa. – People with diabetes are also more often affected by bacterial infections. Staphylococci cause boils, small pus-filled nodules, to form in the skin. Recurring boils or thrush can therefore be the first signs of diabetes in a patient who has not yet been diagnosed. – Prolonged high blood sugar damages the large and small blood vessels, including the smallest vessels that supply the skin. Lack of blood flow to the skin can lead to immune disorders and increase the tendency to infection. – Antidiabetic medication can – although rarely – trigger allergic skin reactions. Therefore, it is worthwhile to study the package insert of the prescribed medication in case of skin reactions.
Skin infections in diabetes
Infections of the skin are directly related to a permanent increase in blood glucose levels. With good metabolic control (blood glucose levels below 200 mg/dl = 11 mmol/l), skin infections are not more common in people with diabetes than in healthy people. Skin, nails or mucous membranes are typical body sites for fungal infections (often Candida albicans). These can also be the first symptoms that indicate manifest diabetes. If the infections recur despite consistent therapy, or if the infection is relatively resistant to therapy, the doctor should clarify whether diabetes is possibly present.
Fungal infection is treated by applying antifungal agents (antifungals) to the skin surface or mucous membranes. Systemic therapy (tablets, infusions) may also be necessary in very severe cases and recurrent fungal infections. Affected skin areas should be well cleaned and cared for. To avoid new infections, it is recommended to wash clothes at least at 60 degrees Celsius.
Infections by bacteria are also possible, which can enter the body through small injuries or on the basis of a previous fungal infection. Erysipelas is a rapidly spreading bacterial infection with hemolytic streptococci or staphylococci. The affected skin areas are red, overheated and swollen and are also accompanied by flu-like symptoms such as fever, chills and fatigue. Erysipelas is a serious disease that must be treated immediately with antibiotics after diagnosis. If therapy is delayed, local blisters may develop-. necrosis or even blood poisoning may occur.
Triggered by the pathogen Corynebacterium minutissimum, erythrasma often occurs in diabetes patients, reddish-brown, slightly scaly areas of skin in skin folds such as the armpit or groin, which usually show no other symptoms. For treatment here, as in the case of a fungal infection, antifungal agents containing azole are used.
The most common skin disease in up to 50 percent of people with diabetes is diabetic dermopathy. In this case, painless, sharply defined oval reddish-brown areas form, mostly on the lower legs. The cause for the development of this clinical picture is the progressive damage to the blood vessels in the skin (microangiopathy) caused by increased blood sugar levels. Diabetic dermopathy improves when blood glucose levels are more carefully controlled.
White spot disease occurs in only about one quarter of the population. The disease occurs in about one percent of the normal population, but in about 4.8 percent of people with diabetes – predominantly type 1. In the course of the disease, the pigment-forming cells (melanocytes) in the skin are lost, probably as a result of autoimmunological processes. For physicians, vitiligo is thus considered a marker that can indicate type 1 diabetes.
A pronounced and rapidly progressing vitiligo can be very disturbing for patients for cosmetic reasons. It is treated with immunosuppressive drugs (e.g., immunosuppressants).B. Tacrolimus or corticosteroids) or with the help of photochemotherapy to promote skin repigmentation.
About itching (lat. Pruritus diabeticorum) up to 40 percent of patients in diabetological practice complain of itching. The severity of the itching does not depend on the blood glucose level. The exact cause of itching in diabetes is unclear, but seems to be related to the dehydration of the skin in diabetes. Poor metabolic control (loss of water, minerals and sugar via the kidneys) leads to systemic fluid deficiency in people with diabetes. The fluid deficit can be aggravated by impaired kidney function with a lack of ability to concentrate the urine, by diuretic medications (so-called. diuretics) and due to insufficient fluid intake (especially in old age). In addition, sweat and sebaceous glands work less effectively due to the nerve damage (autonomic neuropathy) that often occurs in diabetes. The itching can become excruciating if kidney function is extremely limited and the patient must be dialyzed.
Urea-containing creams, lipid-replenishing oil baths, and the short-term use of ointments containing steroids provide relief from chronic itching. Light therapy can also be helpful.
What other skin changes can occur?
Another skin disease is the so-called "necrobiosis lipoidica diabeticorum". These are initially red-spotted, later brown-yellowish skin changes, which also usually occur on the shins. About 60 percent of patients with this condition have type 2 diabetes. However, only 0.5 – 1 percent of all people with diabetes develop necrobiosis lipoidica. Women are affected two to three times more frequently than men.
Pseudoacanthosis nigricans" is also typical: brownish raised spots form in the armpits, on the neck or in the groin. This is thought to be caused by increased insulin secretion in the presence of insulin resistance. Pseudoacanthosis nigricans" develops in up to 90 percent of all people with type 2 diabetes.
Bullosis diabeticorum" This is a spontaneously occurring painless blistering, mostly on the lower legs or feet of older patients with diabetes mellitus that has been present for some time. The triggers are unclear; the level of blood sugar does not seem to play a role. Circulatory disturbances, triggered by diabetic microangiopathy, are held responsible for the development of this condition. In addition, connections with a kidney disease (nephropathy) are discussed, which leads to an imbalance of electrolytes in the skin and thus destabilizes the connective tie structure of the skin.
The "Rubeosis diabeticorum", the symmetrical redness of the cheeks or even the hands, is often found even in adolescents with diabetes. It results from dilation of capillaries in the skin; dilated veins are often visible to the naked eye. This is referred to as telangiectasia.
The "Scleroedema diabeticorum" Describes a change in the connective tie that usually occurs in older and overweight people with diabetes after many years of illness. The skin is thickened and hardened, especially on the upper back and shoulders. The clinical picture can also affect the hands and then manifests itself as the so-called 'stiff hand syndrome'.
Skin reactions as a result of antidiabetic therapy
In rare cases, diabetic patients react with skin reactions to the injection of insulin or the intake of antidiabetic medications. Insulins: Changes in subcutaneous fatty tie at the injection site of insulin injections have become less common with modern insulins. Now only occur in less than one percent of patients (lipodystrophy). – Sulfonylureas may lead to decreased alcohol tolerance. After drinking alcohol, the so-called 'flush' can occur within minutes, a reddening of the face that can be accompanied by a feeling of warmth and headache, and can even lead to cardiac arrhythmia and shortness of breath. Symptoms usually resolve spontaneously over the course of an hour. – During treatment with sulfonylureas, allergic reactions of the immediate type have been observed very rarely (hives, also called urticaria, up to anaphylactic shock). – DPP4 inhibitors (gliptins): considered possible triggers for bullous pemphigoid, phototoxic or anaphylactoid reactions. – SGLT-2 inhibitors: In a large-scale analysis of a total of 21 clinical studies, exanthema, urticaria, and eczema occur more frequently with dapagliflozin. – Biguanides (metformin): Very rarely, skin reactions such as redness, itching, and hives occur during metformin therapy.
However, antidiabetic drugs are also believed to have positive effects on the skin. Metformin is also used in the treatment of dermatological conditions (e.g., dermatitis).B. acne, acanthosis nigricans) is used. GLP-1 receptor agonists (for example liraglutide, dulaglutide) , gliptins and glitazones can also improve inflammatory reactions and also have a positive effect in psoriasis.