Diabetic foot syndrome: symptoms and causes

Diabetic foot syndrome is a condition characterized by lesions:

  1. of the nervous system (diabetic neuropathy)
  2. Blood circulation
  3. of the skin


Effects of high blood sugar levels on circulation

About 5 percent of blood sugar is converted into a simple sugar fraction (called O-GlcNAc) that can alter proteins.
In the blood vessels, this substance prevents phosphorylation (a chemical reaction) of the enzyme that forms nitric oxide.
The result is the increase in oxidative phenomena and thus the production of free radicals that reduce or block the production of nitric oxide (nitric oxide).
Nitric oxide is present in the epithelial cells of blood vessels and causes the following:

  • Vasodilation
  • Inhibition of thrombosis
  • Anti-inflammatory

Nitric oxide requires insulin to adhere to the surface of blood vessels, but this phenomenon is not possible in people with diabetes, insulin deficiency or insulin resistance.
The consequence is that the blood vessels are injured much more easily.
Sources: https://www.scientificamerican.com/article/diabetes-blood-vessel-damage/

Skin changes and deformations in diabetic foot syndrome

The skin is divided into:

  1. Epidermis (outer part).
  2. Dermis (deeper areas), which consist of collagen fibers and elastic fibers.

High blood sugar causes glycosylation (combination of at least one sugar molecule with another molecule), which leads to various changes in the skin:

  1. Thickening of collagen fibers.
  2. Loss of elasticity of elastic fibers.
  3. Injury to the anchoring fibers that hold the dermis and epidermis together.

The consequences are:

  • Separation of epidermis and dermis.
  • The skin is less able to cope with mechanical demands, which causes calluses.
  • Sensitivity and skin dryness, which favor the formation of wounds and ulcers.
  • Formation of blisters between the two layers of skin that can break open and reach the surface of the skin. The blisters may contain (sterile) serum or blood.
  • Hammer toes and hallux valgus.
  • Hollow foot (the opposite of flatfoot).
  • Protruding metatarsal bones (the part of the foot that connects the toes is elevated).

Causes of diabetic foot syndrome

Peripheral neuropathy is a disease caused by diabetes that can affect the nerves.

There are three types of peripheral neuropathy:

  1. Sensory neuropathy (sensitive nerves)
  2. Motor neuropathy (motor nerves)
  3. Autonomic neuropathy (nerves of the autonomic nervous system)

Signs and symptoms of diabetic foot syndrome

The disease begins with a mild form of tingling in the hands and feet and develops gradually until it becomes very painful at an advanced stage.
At the beginning, an ulcer (skin wound) forms on the edge of the nail of the big toe or on the sole of the foot near the toes.
From here, the ulcer can spread to the ankle.

Foot pain caused by diabetes mellitus manifests itself in several ways:

  • Constant burning of the feet.
  • Shooting pain.
  • Foot swelling (edema).
  • Reddening.
  • Formation of ulcers and, in severe cases, gangrene.
  • Muscular atrophy (decrease in size).
  • Displacement of subcutaneous adipose tissue forward, from the underside of the metatarsal head to the underside of the toe bones. The fat under the foot has an important function to protect the bones from hitting the ground. The body forms corns and calluses instead of fat.
  • Aching and weakened muscles on the lower limbs.

Motor neuropathy can lead to a change in posture when walking.
Motor neuropathy causes weakness and pain in the muscular structure, which is permeated by diseased nerves.
The formation of corns and calluses is a consequence of the changed body weight position caused by the foot deformities.

  • Inflamed skin.
  • Ulcers (often infected). In the area of corns and calluses, a hematoma or inflammation is formed, which develops into skin wounds.

Sensory neuropathy is the main cause of the complaints. It manifests itself as “sensitive pain”; it is enough to touch the skin or cover the foot with a bed sheet to provoke pain or discomfort in the feet.

The autonomic neuropathy of the diabetic patient:

  1. Changes the mechanism of sweating.
  2. Dry and cracked skin as well as brittle nails are the most common skin signs. Diabetes affects the nerves that regulate the activity of sweat glands in the skin.
  3. Bacterial and fungal infections cause fever and chills. In people suffering from diabetes mellitus, wound healing occurs very slowly.

Other complications of diabetes

Diabetics are prone to bacterial and fungal infections on the feet due to improper nutrition.
A serious infection can also affect bones and bone marrow (osteomyelitis).

Joint and muscle pain
Another source of foot pain is muscles and joints.
The tendons become rigid and shorten.
This leads not only to muscle pain and pain in the joints, but also to balance problems when walking and changes in posture.

Diagnosis of diabetic foot syndrome and examinations

The doctor conducts a clinical examination (physically) and checks the patient’s medical history.

Assessment of sensitivity (the patient must close his eyes):

    • The doctor uses a needle to see if the patient feels the pain and sting.
    • By stroking the skin with a cotton ball, he checks the sensitivity on the surface of the skin.
    • Thermal sensitivity – While touching the skin with a heated tube or other instrument (thermal threshold), the patient is asked what they feel.
  • By pressing a single plastic thread (Semmes-Weinstein monofilament) onto the patient’s skin, sensitivity to pressure is tested. To do this, it is necessary to press on areas without skin thickening (corns or calluses) in different parts of the forefoot. If the patient does not feel any stimulus at least 6 special points, this means that he suffers from sensory disturbances.
  • To check the vibration sensitivity, a tuning fork is pressed on the outer ankle and the back of the foot. The patient should feel a vibration below 25 hertz.
  • Testing the reflexes with the reflex hammer at the level of the Achilles tendon.
  • testing of movement amplitude and muscle strength,
  • Baropodometry – an examination performed while standing, in which the distribution of body weight is measured on each individual point of the sole of the foot.

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