I. General Complications of Diabetes

The metabolic changes caused by diabetes schematically generate three major types of complications:

Neurological Complications

The involvement of peripheral nerves causes sensory and motor deficits, primarily affecting the nerves of the lower limbs (legs), with a distal predominance. The severity of nerve damage increases as it approaches the extremities.

Vascular Complications

Cholesterol deposits lead to a gradual blockage of large arterial trunks (macroangiopathy) as well as damage to small vessels (microangiopathy). Both phenomena cause arteritis predominantly in the lower limbs and impaired healing. Skin lesions heal poorly, creating potential entry points for germs responsible for infectious diseases.

Infectious Complications

The immune system of diabetic patients is weakened. Diabetics are more susceptible to bacterial infections and are also more vulnerable to skin and nail fungal infections. Furthermore, observed metabolic alterations reduce the effectiveness of antibiotic and antifungal treatments in these patients.

II. Impact of these Complications on the Foot

Consequences of Neurological Impairments

The vast majority of pathologies encountered on the diabetic foot originate from neurological impairments. Two types of lesions in the nervous system should be distinguished:

1. Sensory-Motor Impairments

These impairments of peripheral nerves, primarily affecting the lower limbs, constitute diabetic neuropathy, mainly of the polyneuritis type, leading to motor and sensory disorders

Sensory issues manifest as a gradual impairment of various forms of sensitivity. This includes, to varying degrees, deficits in touch perception, pain, paresthesia, or hypoesthesia. Sensitivity disturbances are also observed.

The onset of these sensory issues is often formidable because the foot, no longer well-informed about external threats or spatial parameters necessary for the fine adjustments required by the complex action of walking, is more susceptible to traumatic risks. This is especially dangerous in diabetics due to their impaired healing and vulnerability to infections.

2. Neurovegetative Impairments:

At the foot level, the vegetative nervous system (VNS), conveyed by motor and sensory nerves, is also affected by the disease.

Instead of evenly distributing arterial blood between the bone structure and the skin, it will favor the vascularization of skin tissues at the expense of the skeleton. This dysfunction leads to a disruption of the bone apposition/resorption system, responsible for diabetic arthropathies.

3. Osteoarticular and Cutaneous Impairments Induced by Neurological Degeneration:

Cutaneous Consequences of Neurological and Osteoarticular Impairments on the Foot

The various bone deformities will alter the shape of the foot and the uniformity of its plantar supports. Pathological walking pressures will emerge, leading to the formation of calloused areas (hyperkeratosis) in areas of higher pressure. The lack of pain sensitivity often present at this stage of the disease, along with a lack of prevention, is often responsible for the transformation of these calluses into plantar ulcers.

In the absence of prompt intervention, these skin lesions progress towards chronicity as healing does not occur, and osteitis (skeletal involvement) is often a concern.

Blisters that may appear due to friction with shoes, though seemingly common, should be promptly treated under good aseptic conditions. They pose a risk of infection with the known dramatic consequences in a diabetic context.

Most of these pathologies occur at a stage of diabetic disease where the patient does not experience painful symptoms and, if not educated by healthcare professionals, may overlook a benign lesion that could ultimately have catastrophic effects. Simple yet rigorous care at the onset would have been sufficient for treatment.

Consequences of Arterial, Osteoarticular, and Cutaneous Disorders

Associated Cutaneous Lesions:

These severe lesions are caused by ischemic involvement of the arteries in the lower limbs, within the context of diabetic macroangiopathy. They result in a reduction of arterial blood flow to the foot, with a decrease or abolition of arterial pulses and cooling of the skin. Eventually, ulcers may occur, leading to toe necrosis and sometimes complicated by gangrene.