Chapter 4 – SKIN INJURIES ON THE DIABETIC FEET.

Our body uses the skin as its first line of defense against bacterial invasion. The skin contains highly specialized structures such as blood vessels, nerves, hair follicles, sweat glands, and sebaceous (oil) glands. The nerve supply to the skin serves both sensory and motor functions. Sensory nerves allow us to feel touch, heat, cold, and pain, while involuntary nerves control the sweat glands, the small blood vessels, and the muscles of the foot and leg. When diabetes mellitus causes changes in these nerves and small blood vessels, the skin's color and texture begin to change. Bluish, reddish, or whitish hues—along with variations in hair presence and a decrease in skin texture —are typical signs of diabetic foot problems.

Skin changes can be the first sign of many complications related to diabetic foot. Skin lesions are common in diabetic patients and often occur alongside other diabetes related complications, such as kidney and eye problems.

The most common initial and subsequent skin lesions in diabetics are dermatopathies. Brown spots—skin lesions commonly located on the shins—are frequently seen in diabetics. These lesions, which are about half an inch in diameter, often feature a slight, sometimes crusted, central depression. Although the exact cause of dermopathy in diabetics is unknown, these lesions typically improve over time and rarely ulcerate or become infected, so they usually do not require treatment.

The next common skin lesion in diabetics is called Necrobiosis Lipoidica Diabeticorum (NBLD). NBLD lesions are most commonly observed on the shins but can appear anywhere on the body. These lesions typically have a yellow central area with a brownish-red periphery. They often sting and burn and may eventually ulcerate. However, unless the lesions ulcerate, treatment is generally not required. NBLD frequently appears even before the onset of diabetes and is more common in women. It is considered a more severe form of diabetic dermopathy, although its exact cause remains unclear.

Blistering lesions on the diabetic foot, known as Bullosis Diabeticorum, are seen in patients with poor blood sugar control. These lesions can appear as superficial or deep blisters on the skin, varying in size from small to large. They develop quickly without any prior injury and are typically painless. Once a blister occurs, immediate medical attention is required to differentiate it from injuries caused by poor circulation or neuropathy. Although these blisters generally heal very slowly, they can sometimes become infected, and the infection may spread to deeper structures in the foot, potentially causing bone infection (See Fig. 4-6).

Itching is quite common in diabetes, and when it becomes severe on the foot, it can be especially uncomfortable and disruptive at night. Although the exact cause is unknown, affected individuals generally have very dry skin. Sometimes, uremia—a condition caused by an accumulation of toxic byproducts in the blood—can also lead to itching. Treatment is necessary because the persistent scratching can lead to infection in the affected area. Steroid-containing creams may help relieve the itching, and maintaining good blood sugar control appears to be beneficial as well.