What are the causes of post‑dialysis hyperglycaemia in haemodialysis patients?

Causes of Post-Dialysis Hyperglycemia

Post-dialysis hyperglycemia occurs primarily due to impaired osmotic diuresis, post-dialysis meal intake after pre-dialysis fasting, and the accumulation of uremic toxins that contribute to insulin resistance. 1

Primary Mechanisms

Impaired Osmotic Diuresis

• The kidneys normally excrete excess glucose through osmotic diuresis, but in hemodialysis patients this mechanism is absent, allowing glucose to accumulate after dialysis sessions 1

Post-Dialysis Meal Intake After Fasting

• Patients typically fast before dialysis and then eat immediately afterward, creating a large glucose load that cannot be adequately cleared due to impaired renal function 1
• This post-dialysis meal occurs at a time when insulin sensitivity is already compromised 1

Uremic Toxin Accumulation

• Uremic toxins accumulate between dialysis sessions and contribute to insulin resistance and postprandial hyperglycemia 1
• Although dialysis removes some uremic toxins and temporarily improves insulin sensitivity, the toxins re-accumulate between sessions 1

Dialysate-Related Factors

Glucose Concentration in Dialysate

• The glucose concentration of the dialysate is the main determinant of plasma glucose levels after hemodialysis 1
• Historically, high-glucose dialysate solutions (up to 1600 mg/dL) led to significant hyperglycemia 1
• Even with modern glucose-free or low-glucose dialysates, rebound hyperglycemia can occur 2

Counterregulatory Response (Somogyi-Like Effect)

Rebound Hyperglycemia After Intradialytic Hypoglycemia

• Several hours after hemodialysis completion, paradoxical rebound hyperglycemia may occur through a mechanism similar to the Somogyi effect 2
• During dialysis, glucose levels progressively decline, reaching their lowest point at the end of the session, which triggers counterregulatory hormone release 1, 3
• This hormonal response, combined with insulin resistance, causes glucose levels to peak approximately 2.5 hours after dialysis ends 4

Metabolic Changes During and After Dialysis

Increased Erythrocyte Glucose Uptake During Dialysis

• During hemodialysis, increased erythrocyte glucose uptake contributes to lower glucose levels during the session 1
• After dialysis ends, this mechanism reverses, contributing to glucose accumulation 1

Removal of Uremic Toxins Temporarily Improves Insulin Sensitivity

• Dialysis removes uremic toxins, which paradoxically leads to less severe insulin resistance immediately post-dialysis 1
• However, this improved sensitivity is short-lived as toxins re-accumulate, and the post-dialysis meal overwhelms this temporary improvement 1

Timing and Pattern

Predictable Glycemic Pattern

• Glucose levels drop progressively during hemodialysis, reaching their nadir at the end of the dialysis session 1, 3, 2
• Post-dialysis hyperglycemia typically peaks 2.5 hours after dialysis ends 4
• This creates a characteristic pattern of intradialytic hypoglycemia followed by post-dialysis hyperglycemia 2, 5

Clinical Implications

Common Pitfall: Overtreatment of Post-Dialysis Hyperglycemia

• Clinicians may be tempted to increase insulin doses in response to post-dialysis hyperglycemia, but this increases the risk of dangerous intradialytic and nocturnal hypoglycemia 4, 3
• Target more moderate fasting glucose levels of 110-130 mg/dL rather than aggressive control, as very low HbA1c creates a U-shaped mortality curve in hemodialysis patients 4, 6, 3

Monitoring Strategy

• Continuous glucose monitoring is superior to point-of-care testing for detecting these glycemic excursions, as traditional monitoring misses most episodes 1, 4, 3
• Monitor glucose at minimum: pre-hemodialysis, mid-hemodialysis (2 hours), end of hemodialysis, and 2-3 hours post-hemodialysis 3