Practice Essentials
Diabetes increases susceptibility to various types of infections. The most common sites of infection in diabetic patients are the skin and urinary tract.
Ear, Nose, and Throat Infections
Malignant otitis externa and rhinocerebral mucormycosis are 2 head-and-neck infections seen almost exclusively in patients with diabetes.
Malignant or necrotizing otitis externa principally occurs in diabetic patients older than 35 years and is almost always due to Pseudomonas aeruginosa.
Infection starts in the external auditory canal and spreads to adjacent soft tissue, cartilage, and bone. Patients typically present with severe ear pain and otorrhea.
Rhinocerebral mucormycosis collectively refers to infections caused by various ubiquitous molds.
Invasive disease occurs in patients with poorly controlled diabetes, especially those with diabetic ketoacidosis. Organisms colonize the nose and paranasal sinuses, spreading to adjacent tissues by invading blood vessels and causing soft tissue necrosis and bony erosion.
Urinary Tract Infections
Patients with diabetes have an increased risk of asymptomatic bacteriuria and pyuria, cystitis, and, more important, serious upper urinary tract infection.
Intrarenal bacterial infection should be considered in the differential diagnosis of any patient with diabetes who presents with flank or abdominal pain.
Pyelonephritis makes control of diabetes more difficult by causing insulin resistance; in addition, nausea may limit the patient’s ability to maintain normal hydration. Treatment of pyelonephritis does not differ for patients with diabetes, but a lower threshold for hospital admission is appropriate.
Skin and Soft Tissue Infections
Sensory neuropathy, atherosclerotic vascular disease, and hyperglycemia all predispose patients with diabetes to skin and soft tissue infections. These can affect any skin surface but most commonly involve the feet.
Bullosis diabeticorum is a spontaneous, noninflammatory, blistering condition of acral skin that is unique to patients with diabetes mellitus. Blisters in this disease typically heal spontaneously, within 2-6 weeks, but secondary infection may develop.
Other Infections
Contiguous spread of a polymicrobial infection from a skin ulcer (particularly a chronic ulcer) to adjacent bone is common in patients with diabetes.
Although cholecystitis is probably no more common in patients with diabetes than in the general population, severe, fulminating infection, especially with gas-forming organisms, is more common.
The incidences of staphylococcal and Klebsiella pneumoniae infections are greater in people with diabetes than in people without diabetes, and cryptococcal infections and coccidioidomycoses are more virulent in patients with diabetes. Also, diabetes is a risk factor for reactivation of tuberculosis.