How does Diabetes Mellitus (DM) increase the risk of Pyelonephritis?

From the Guidelines

Diabetes significantly increases the risk of pyelonephritis due to impaired immune function, urinary tract abnormalities, and other factors that create an environment conducive to bacterial growth and infection. According to the most recent and highest quality study 1, diabetic patients are considered high-risk for complications from acute pyelonephritis, including renal abscesses and emphysematous pyelonephritis. The mechanisms by which diabetes increases the risk of pyelonephritis include:

• High blood glucose levels that compromise white blood cell function and create an environment where bacteria can thrive
• Autonomic neuropathy that can lead to incomplete bladder emptying and urinary retention, allowing bacteria to multiply in stagnant urine
• Glycosuria, which provides nutrients for bacterial growth
• Structural changes in the kidneys and impaired local immune responses in the urinary tract
• Development of asymptomatic bacteriuria that can progress to pyelonephritis if left untreated

As noted in 1, high-risk patients, including those with diabetes, require prompt and effective treatment to prevent complications and improve outcomes. Therefore, diabetic individuals should prioritize good glycemic control, adequate hydration, proper hygiene, and seek prompt medical attention for urinary symptoms to prevent progression to serious kidney infections. Additionally, healthcare providers should be aware of the increased risk of pyelonephritis in diabetic patients and take steps to prevent and promptly treat urinary tract infections in this population, as recommended in 1 and 1.

From the Research

Diabetes and Pyelonephritis Risk

Diabetes increases the risk of pyelonephritis due to several factors, including:

• Chronic hyperglycaemia, which encourages urinary tract infections 2
• Disorders of the autonomic nervous system, leading to disturbances of bladder voiding, particularly in diabetic women aged over 50 2
• Pregnancy, which is a facilitating factor in younger women 2
• The presence of diabetes-related glomerulopathy with nephroangiosclerosis and interstitial lesions, which can aggravate infections 2

Complications of Pyelonephritis in Diabetic Patients

Pyelonephritis in diabetic patients is often more severe and complicated, with:

• A higher incidence of acute papillary necrosis, emphysematous pyelonephritis, and bacteremia with metastatic localization to other sites 3
• Increased risk of pyonephritis or papillary necrosis, which can threaten the patient's life or renal function 2
• Reduced effectiveness of antibiotics due to decreased tissue levels, leading to more frequent and resistant relapses 2

Clinical Features and Treatment Outcomes

Studies have shown that:

• Diabetic patients with pyelonephritis often present with severe disease, including renal abscess and papillary necrosis 4
• Escherichia coli is the most common organism isolated in these patients 4, 5
• Treatment outcomes are often poor, with high rates of mortality and renal dysfunction 4, 5
• Early diagnosis and aggressive management of emphysematous pyelonephritis in type 2 diabetic patients can improve outcomes 5

Bilateral Pyelonephritis in Diabetic Patients

Bilateral pyelonephritis is more common in diabetic patients, particularly women, and is often associated with:

• Newly diagnosed diabetes mellitus 6
• Severe disease, including renal dysfunction and increased risk of complications 6
• The need for prompt diagnosis and treatment to prevent long-term renal damage 6