How Does Diabetes Affect the Immune System? 

Diabetes and infection are a well-known relationship in the clinical community.^1,2 Studies have demonstrated that diabetes negatively affects the immune system and increases rates of infection in this population.

Experts believe that the hyperglycemic (ie, high blood glucose) environment in diabetes promotes immune dysfunction.³ Individuals with diabetes are at a greater risk of breaking their natural barrier, their skin, to infection due to neuropathy and have a higher risk of developing foot ulcers and requiring amputations. In addition, diabetes also affects cellular immunity. Studies show that hyperglycemia provides a favorable environment for infectious microorganisms while reducing the responses and functions of immune cells.^3,4 Impairment of immune cells like neutrophils and T lymphocytes are commonly observed, along with decreased antioxidant system, defective antibody-mediated immunity, and antibacterial activity in urine. Along with changes in immunity seen on a cellular level, adverse blood vessel-related changes associated with diabetes hinder the transport of immune cells to critical locations in the body, further inhibiting the immune system.²

What Infections Are Common in Diabetes?

There are largely two categories of infections commonly seen in individuals with diabetes.² One category refers to infections common in the general population that present themselves more severely in individuals with diabetes. The other category refers to infections rare to the general population but are peculiarly seen in individuals with diabetes. 

Common Infections:⁴

• Pneumonia
• Pulmonary tuberculosis
• Gastrointestinal infections
• Urinary tract infections
• Skin and soft tissue infections

Rare Infections Peculiar to Diabetes:²

• Rhinocerebral mucormycosis
• Necrotizing fasciitis
• Renal papillary necrosis
• Malignant otitis externa
• Emphysematous cholecystitis
• Emphysematous pyelonephritis

Are Infections More Dangerous in Diabetes?

Infections often more severely affect individuals with diabetes than those without.^1,4 Studies show that infections in diabetes are more likely to require antibiotic treatment and more likely to progress to serious forms of infection (eg, sepsis). In addition, the risk of being hospitalized for infection and, in rare cases, dying from infection are also higher in those with diabetes than those without. It is estimated that nearly 6% of hospitalizations and 12% of infection-related deaths are attributable to diabetes and that individuals with diabetes have near-double the risk of hospitalization compared to individuals without.⁵