Infections associated with diabetes: an introduction

Diabetes can have a profound effect on how the body functions, especially if blood sugar remains uncontrolled. Uncontrolled blood sugar promotes cardiovascular disease (atherosclerosis, heart disease), cerebrovascular disease (stroke), and peripheral vascular disease, as well as damage to the kidney and damage the nerves. In addition, uncontrolled blood sugar can change immune system function, making the body less able fight infection. All of these negative health effects can work together to interfere with the body’s ability to fight infection effectively and even interfere with our ability to detect the signs of an infection.1

For this reason, people with uncontrolled diabetes tend to develop infections more commonly and these infections tend to be more severe. The main types of infections that occur in people with diabetes include2 :

  • Foot infections
  • Urinary tract infections
  • Fungal infections (affecting the mouth, skin and nails)
  • Bacterial infections of the skin and soft tissues
  • Influenza and pneumonia

How does diabetes affect the immune system and increase risk for infections?

Diabetes with uncontrolled blood glucose can interfere with how your immune system works, rendering it less able to protect against infection. Our immune system is made up of many different cells and chemicals whose job it is to fight invasion or infection by foreign substances or organisms, such as viruses and bacteria. The most important cells involved in the immune system are white blood cells. There are several types of white blood cells, each with a specific role to play in fighting infection.. High blood sugar can make white blood cells less able to kill and dispose of organisms that invade the body. Additionally, when the body is trying to fight off an infection, it experiences an increase in stress, which causes production of a number of different hormones, including cortisol and glucagon, which trigger release of glucose from the liver, making glucose levels rise significantly. 2,3

How can I lower my risk of getting an infection?

If you have uncontrolled diabetes, you are at increased risk for a range of infections. However, there are several simple, practical steps that you can take to protect yourself against the development of infections. These include:

You and your family and friends should practice good hygiene. Wash your hands frequently and covering your mouth when you cough or sneeze.

Keep your blood glucose under control. Elevated blood glucose is associated with immune system impairment (as well as many other complications of diabetes). So, to protect against infection and other health problems, you should make a point of keeping your blood glucose under control.

Get vaccinated. Getting an influenza vaccine (unless you are allergic to the vaccine) every year is a good way to avoid contracting the flu, or, if you get the flu, making sure it is less severe. There are several other vaccines that you can get to protect against other infections, including shingles and pneumococcal pneumonia. For instance, the US Centers for Disease Control and Prevention (CDC) recommends that all adults 60 years of age and older should get a shingles vaccine and that all children (from age 2 years and up) and adults with diabetes should get a pneumococcal pneumonia vaccine. You can learn more about CDC recommendations for vaccinations at the CDC website. Talk to your doctor about whether you might benefit from these vaccines.

Make healthy lifestyle changes. You can reduce your risk of infection by being as healthy as you can. This includes quitting smoking (if you smoke), losing excess weight and keeping it off, keeping your blood pressure and lipids under control, getting regular exercise of moderate intensity, and adopting an energy-appropriate and nutrient-dense eating pattern. A healthy eating pattern should be based on recommendations for the general public in the US Department of Agriculture’s Dietary Guidelines for American, 2010 and should include a high intake of fruits, vegetables, and dietary fiber and a low intake of total fat, saturated fat, and added sugars.

Infections of the foot

People with uncontrolled diabetes are at higher risk for developing foot infections, both because of impaired immune system function and because nerve damage (neuropathy) can lead to loss of sensation, increasing risk for undetected injury. Additionally, peripheral vascular disease (also called peripheral artery disease [PAD]), in which arteries that supply the feet become clogged, cuts the supply of blood to the feet, making wound healing slower and the delivery of antibiotics to the feet more difficult.

Treatment for foot infections depends on the seriousness of the infection and typically involves use of antibiotics (oral or intravenous). While your foot is infected, it is very important to keep pressure off the wound so that it can heal properly. This may require bed rest or the use of a wheelchair or crutches or custom footwear. Additionally, removal of infected and dead tissue may be necessary. Without the proper treatment, foot infections can progress to the point where amputation is necessary. So, if you develop a foot infection, it is very important to get help immediately and if you have diabetic neuropathy that affects your feet, you should get in the habit of checking your feet on a daily basis.3

Infections of the urinary tract

Infections of the urinary tract, including the bladder and the kidney, are more common in people with diabetes.

Bladder infection. Bladder infection (also called cystitis) are associated with signs and symptoms. These include increased need to urinate more frequently and pain and burning during urination. Urine may also have blood in it and may be cloudy with an unpleasant odor. A person with cystitis may also experience pain in the area over the bladder and fever. The standard treatment for cystitis caused by a bacterial infection is a course of antibiotics for 3 to 7 days. Bladder infections can sometimes be caused by fungus (people with uncontrolled diabetes are at higher risk for this kind of bladder infection). A fungal infection requires treatment with an antifungal medication. Fungal infections of the urinary tract may also be associated with the growth of a large mass of fungus, which may require surgery to remove.3

Kidney infection. Infection of the kidney (also called pyelonephritis) occurs when bacteria migrate up the tubes (the ureters) that connect the kidney with the bladder. This type of infection can occur at the same time as a bladder infection or develop afterwards. Pyelonephritis is associated with symptoms including nausea, vomiting, fever, chills, and severe pain affecting the side or upper back. If a kidney infection is not severe, it can be treated with a course of antibiotics or an antifungal medication (depending on the organism causing the infection) at home. However, if symptoms are severe, intravenous antibiotic treatment may require a short hospitalization.3

In rare cases a more serious type of kidney infection called emphysematous pyelonephritis may develop. This condition is characterized by the presence of gas in the kidneys, produced by bacteria or fungi from high blood glucose levels in the tissue of the kidney. Emphysematous pyelonephritis is an extremely dangerous condition that requires immediate hospitalization.3

Infections of the skin and nails

Diabetes is associated with increased risk for several infections of the skin and nails, including onychomycosis, tinea pedis, and cellulitis.3

Onychomycosis. Onychomycosis is a fungal infection that affects the fingernails or toenails, resulting in thickened, yellowed nails that can lift or separate from the skin beneath. This fungal infection is typically treated with oral (systemic) or topical antifungal medication.

Tinea pedis. Tinea is a fungal infection that affects the skin between the toes, resulting in cracking and itching of the skin of the toe web. It is typically treated with a topical antifungal medication.

Cellulitis. Cellulitis is the term used for any bacterial infection of the skin and underlying tissues. The typical signs and symptoms of cellulitis include painful, swollen, red skin (sometimes with blistering). It may also include a fever. Treatment for cellulitis typically includes antibiotics. It may also involve surgical removal of dead or infected tissue.

Other infections

Additionally, there are several infections that are rare and serious (usually requiring hospital care) and tend to occur almost exclusively in people with diabetes. These include2,3:

  • Malignant external otitis. This is a severe type of ear infection that can spread from the external ear canal to the soft tissue and, eventually, the bone next to the ear canal. It is most often seen men who are over the age of 65 years and have had diabetes for many years. Signs of this condition include severe painful earache with festering discharge from the ear. Treatment requires 6 weeks of antibiotics, with surgical removal of tissue necessary if the infection has progressed.
  • Rhinocerebral mucormycosis. An infection of the sinuses or palate of the mouth associated with ketoacidosis. The signs of this condition include pain in the area of the eyes or front of the face, with nasal discharge that is yellowish-white and may contain blood. The danger with rhinocerebral mucormycosis is spread of infection to the brain. Treatment involves antibiotic or antifungal agent. Additionally, dead or infected tissue my need to be surgically removed.
  • Emphysematous cholecystitis. An infection of the gallbladder by gas-forming bacteria. Unless treated promptly, this dangerous condition may result in perforation of the gallbladder or gangrene. The chance of emphysematous cholecystitis being fatal is high, so rapid detection and treatment is important. Treatment typically requires removal of the gallbladder and antibiotic therapy.
Written by: Jonathan Simmons | Last reviewed: May 2014.
View References