Does having pre-diabetes (impaired glucose regulation) increase susceptibility to viral illnesses?

Pre-Diabetes and Viral Illness Susceptibility

Yes, having pre-diabetes does increase your susceptibility to viral illnesses, particularly severe complications from viral infections like COVID-19, influenza, and other respiratory viruses. The evidence demonstrates that impaired glucose regulation creates immune dysfunction and chronic low-grade inflammation that compromises your body's ability to fight viral infections effectively.

Mechanisms of Increased Viral Susceptibility

Pre-diabetes impairs your immune system through several interconnected pathways:

• Chronic low-grade inflammation with overproduction of proinflammatory cytokines reduces natural killer cell number and activity, impairing your body's first-line antiviral defenses 1, 2
• Impaired antigen-stimulation responses compromise both innate and adaptive immune functions, making it harder to mount an effective response against viral pathogens 1, 2
• Altered ACE2 receptor expression from chronic hyperglycemia downregulates this protective enzyme, which paradoxically makes cells more vulnerable to viral entry and subsequent hyperinflammation 1
• Reduced phagocytosis and neutrophil chemotaxis directly impair your ability to clear viral particles 1

Evidence from COVID-19 and Other Viral Infections

The COVID-19 pandemic provided the clearest evidence of this relationship:

• Pre-diabetes was associated with 10.8 times higher risk of pneumonia from COVID-19 compared to those with normal glucose metabolism 3
• Pre-diabetes increased risk of hyponatremia (8.83-fold) and hypokalemia (4.58-fold) during viral infection 3
• 73.7% of patients with undiagnosed diabetes and 100% with undiagnosed pre-diabetes only discovered their condition during COVID-19 hospitalization, highlighting how common unrecognized glucose dysregulation is 3

Historical data from the 2009 H1N1 influenza pandemic showed similar patterns, with impaired glucose metabolism contributing to more severe illness and prolonged ICU stays 1.

The Bidirectional Relationship

The relationship between viral infections and glucose dysregulation works both ways:

• Viral infections can trigger or worsen pre-diabetes through pro-inflammatory cytokines that promote insulin resistance 4, 5
• SARS-CoV-2 specifically can impair insulin secretion by pancreatic β-cells and cause insulin resistance in liver, skeletal muscle, and adipose tissue 5
• Approximately one-third of patients develop new-onset pre-diabetes or diabetes after acute pancreatitis, which can be triggered by severe viral infections 1

Clinical Implications and Screening

Given this increased vulnerability, specific actions are warranted:

• Annual screening for pre-diabetes is recommended if you have risk factors including overweight/obesity (BMI ≥25 kg/m² or ≥23 kg/m² in Asian ancestry), first-degree relative with diabetes, high-risk ethnicity, hypertension, or physical inactivity 1
• Testing should begin at age 35 years for all adults, or earlier if risk factors are present 1
• People with pre-diabetes (A1C 5.7-6.4%) should be tested yearly to monitor progression 1

Vaccination Priority

Because of increased susceptibility to severe viral complications:

• People with pre-diabetes should be prioritized for viral vaccinations, including COVID-19, influenza, and other recommended vaccines 1
• The immune response to vaccination appears preserved in pre-diabetes, making vaccination an effective preventive strategy 1

Common Pitfalls to Avoid

The most critical pitfall is undiagnosed pre-diabetes—the majority of people with pre-diabetes don't know they have it until a severe infection occurs 3. This is particularly problematic because:

• You cannot take preventive measures if you don't know you have the condition
• Viral infections in undiagnosed pre-diabetes can precipitate acute metabolic crises
• Early identification allows for lifestyle interventions that can prevent progression to diabetes and reduce infection risk

Another pitfall is assuming that pre-diabetes is "not serious enough" to warrant concern about infections—the evidence clearly shows that even this intermediate state of glucose dysregulation significantly impairs immune function 2, 4.