By Dr Ananya Mandal, MD
Diabetes mellitus is a condition where the body is unable to control the blood sugar. Normally the body has a good immune system that fights against microbes and invading organisms that may lead to infections. The white blood cells are the main fighters in this respect to keep the body protected. (1-5)
In patients with diabetes, the immune system of a person is affected. In addition, the blood vessels are damaged due to the excessive blood sugar running in the veins.
Peripheral neuropathy and gangrene
Also diabetes leads to damage to the nerves in the long run. This is called peripheral neuropathy. This leads to lack or decreased pain sensation. So if a diabetic patient gets accidentally poked, hurt, cut or burnt especially in the limbs or extremities like toes and fingers he or she may not be aware because the cut may not hurt.
Pain usually alerts a normal person to care for a hurt area in order to prevent infections. In diabetics this is absent and the wound often gets infected.
Diabetes and the immune system
Further diabetes weakens the immune system which is unable to fight the invading organisms at the wound. High blood sugar makes the blood more favourable for bacterial and microorganisms to grow.
Foot infections in diabetics
In diabetics the common sensitive areas affected are lungs, skin, feet, urinary tract, genital area and mouth.
In diabetics skin infections are detected commonly because of their visibility and not because of their pain.
Diabetics commonly get foot infections. This is because the feet are commonly exposed to injury and bumps and bruises in the activities of daily living.
Foot infections may begin as small ulcers and may invade deeper tissues, lead to gangrene or affect the bones and invade the blood stream as well.
It is found that nearly half of the people with diabetes who visit the diabetic foot clinics have peripheral neuropathy and nearly half of them have both neuropathy and narrowing of blood vessels. (3)
Diabetic foot infections are seen commonly in those with diabetes associated problems like kidney or eye problems. Those who are prone to cuts, wounds, burns and corns or calluses over their foot are at risk of diabetic foot infections.
Bunions and pressure points are usually starting point of infections and ulcers. Those with leg problems or other problems like obesity that prevent them from bending to care for their feet are also at risk.
Diabetic foot and gangrene
Gangrene is the most dreaded form of diabetic foot. There is death or decay of the affected foot. Gangrene usually affects diabetics with high and uncontrolled blood sugar.
It is found that high blood sugar damages the nerves of the foot causing peripheral neuropathy and also hardens the walls of the arteries leading to narrowing and obstructed blood supply. These are main causative factors of a raised risk of gangrene in diabetics.
Diabetic foot is classified according to a classification system by Wagner (3);
- Grade 0 when the skin over the foot is intact
- Grade I superficial or surface ulcer
- Grade II deeper ulcer
- Grade III osteomyelitis or bone affliction and/or deep abscess
- Grade IV forefoot (front of the foot) gangrene
- Grade V hindfoot (heels and back of the foot affected) gangrene
Hospitalization is important for gangrene and severe diabetic foot. Laboratory diagnosis is performed to find the causative organism and the antibiotics that are potent against the infection.
Surgical therapy like debridement and regular dressing is important for early healing. In severe cases the rest of the foot and the body may be saved only be amputating the gangrenous area. The toes are the first to be amputated and if the infection refuses to stop the whole foot may have to be surgically amputated.
Prevention of gangrene in diabetics
Thus diabetics need to prevent gangrene. The major preventive measures include:
- Continuous monitoring of blood sugar and tight control of blood sugar within normal levels.
- Adequate foot care. Diabetics need to inspect their feet every day for minor injuries and infections which they may not have been able to feel.
In addition they need to maintain good foot hygiene keeping in dry and warm. The feet must be rested often. They need to visit the podiatrist at least once a year for check-ups.
- Shoes should be chosen carefully. Special diabetic foot soles and pads are used to prevent injuries. Tight shoes, high heeled ones and flip flops are best avoided.
Reviewed by April Cashin-Garbutt, BA Hons (Cantab)
Last Updated: Jul 29, 2012