Can a urinary tract infection (UTI) cause elevated blood sugars?

Can Elevated Blood Sugars Be Caused by UTI?

Yes, urinary tract infections (UTIs) can cause elevated blood sugar levels, particularly in patients with diabetes, due to the body's stress response to infection.

Mechanism of UTI-Related Hyperglycemia

• Infections, including UTIs, trigger a stress response in the body that leads to the release of counterregulatory hormones (cortisol, growth hormone), which can increase blood glucose levels 1
• The inflammatory state caused by UTIs can contribute to insulin resistance, further elevating blood glucose levels 1
• In patients with diabetes, this stress-induced hyperglycemia can be more pronounced due to already impaired glucose metabolism 1
• The persistent mild inflammatory state associated with infections can exacerbate insulin resistance, particularly in patients with compromised kidney function 1

Evidence from Clinical Studies

• Research has demonstrated a significant association between UTIs and elevated admission blood glucose levels in hospitalized patients without diabetes 2
• In a study of patients hospitalized for UTI, those without diabetes but with admission blood glucose levels between 111-199 mg/dl had 1.85 times higher risk of 30-day mortality compared to those with normal glucose levels 2
• Even more concerning, patients without diabetes but with admission blood glucose ≥200 mg/dl had 2.94 times higher risk of 30-day mortality 2
• Interestingly, this association between admission blood glucose and mortality was not observed in patients with pre-existing diabetes 2

Bidirectional Relationship Between UTIs and Blood Glucose

• Not only can UTIs cause hyperglycemia, but elevated blood glucose can also increase susceptibility to UTIs 3, 4
• Glucosuria (glucose in urine) creates a favorable environment for bacterial growth in the urinary tract 5
• When blood glucose levels exceed the renal threshold (typically around 180 mg/dL), glucose spills into the urine, potentially increasing UTI risk 5
• Poor glycemic control is identified as a risk factor for UTIs in diabetic patients 3, 4

Clinical Implications

• When a patient presents with unexpectedly elevated blood glucose, UTI should be considered as a potential cause, especially in diabetic patients 6
• For diabetic patients with sudden worsening of glycemic control, checking for UTI is advisable, even if typical urinary symptoms are absent 6, 3
• Persistent hyperglycemia due to untreated UTI can potentially progress to diabetic ketoacidosis (DKA) in susceptible individuals 6
• When treating a UTI in a diabetic patient, more frequent blood glucose monitoring may be necessary to adjust diabetes medications appropriately 1

Management Considerations

• Treating the underlying UTI is essential to resolve the stress-induced hyperglycemia 6
• During UTI treatment, diabetic patients may require temporary adjustments to their diabetes medications to maintain glycemic control 1
• Ensure adequate hydration and monitor for ketones if hyperglycemia is severe 6
• In patients with advanced kidney disease and UTI, careful monitoring is particularly important as they are prone to both hyperglycemia and hypoglycemia depending on their stage of kidney disease 1

Special Considerations

• In patients using SGLT-2 inhibitors (a class of diabetes medications), UTIs may occur more frequently, potentially creating a cycle of infection and hyperglycemia 7
• However, most UTIs in patients taking SGLT-2 inhibitors are mild to moderate and respond well to standard antibiotic treatment 7
• For patients with recurrent UTIs and diabetes, optimizing glycemic control is an important preventive strategy 3, 4