How should blood glucose levels be managed in a patient undergoing hemodialysis (HD)?

Blood Glucose Management in Patients Undergoing Hemodialysis

Use continuous glucose monitoring (CGM) as the primary monitoring strategy for patients with diabetes on hemodialysis, and reduce total daily insulin dose by 35-50% depending on diabetes type, with additional 25% basal insulin reduction on pre-dialysis days. 1

Insulin Dose Adjustments

For patients with type 1 diabetes on hemodialysis, reduce total daily insulin dose by 35-40%. 1 For patients with type 2 diabetes, the reduction should be more aggressive at approximately 50%. 1 These substantial reductions are necessary because the kidney normally clears 30-80% of insulin, and decreased kidney function leads to reduced insulin clearance and prolonged insulin action. 1

Specific Timing Considerations

• Reduce basal insulin by an additional 25% on pre-hemodialysis days to prevent hypoglycemia during the dialysis session. 1
• Total daily insulin requirements may decrease by 15% post-dialysis, with a 25% reduction in basal insulin needs the day after dialysis compared to the day before. 2, 1
• No changes in bolus insulin requirements are typically needed, but the basal adjustments are critical. 2

Continuous Glucose Monitoring Strategy

CGM should be the preferred monitoring method rather than traditional fingerstick glucose measurements because it detects asymptomatic hypoglycemia that occurs in 46-52% of ambulatory diabetic patients on maintenance hemodialysis. 2, 1 Traditional monitoring misses most hypoglycemic episodes. 1

CGM Accuracy Considerations

While CGM accuracy is somewhat reduced in hemodialysis patients (mean absolute relative difference ~20% vs. blood glucose), nearly all CGM values fall in clinically acceptable zones that are unlikely to cause significant harm. 3 The accuracy is slightly lower during hemodialysis periods (22.0%) versus non-hemodialysis periods (18.2%). 3

Consider calibrating the CGM sensor after rapid volume changes during or immediately after hemodialysis sessions using a hybrid model of CGM and glucose meter system, as fluid shifts during dialysis can affect the relationship between interstitial glucose sensor readings and actual blood glucose levels. 2

Glycemic Targets

Target more moderate fasting glucose levels of 110-130 mg/dL rather than aggressive targets, as very low HbA1c levels (≤5.4%) are associated with increased mortality in hemodialysis patients, creating a U-shaped mortality curve. 1 Similarly, high HbA1c levels (≥8.5%) also increase mortality risk. 2

Aim for HbA1c of 7-8% in dialysis patients with high comorbidity burden or hypoglycemia risk, rather than the standard <7% target. 1

Glucose Monitoring During Hemodialysis

Expected Glycemic Patterns

• Glucose levels drop progressively during hemodialysis, reaching their lowest point (nadir) at approximately the third hour of dialysis. 2, 1
• Post-dialysis hyperglycemia typically peaks 2.5 hours after dialysis ends. 2, 1
• Sensor glucose levels may fall well below the dialysate glucose concentration toward the end of hemodialysis, even when using dialysate containing 100-150 mg/dL glucose. 4

Monitoring Frequency

Monitor blood glucose more frequently on dialysis days and the day after, particularly during and immediately following the dialysis session. 1 Testing post-dialysis glucose levels earlier than 60 minutes post-treatment may miss the need for additional medication, as glucose variability is greatest at 60 minutes post-hemodialysis. 5

Hypoglycemia Prevention

All hypoglycemic episodes during hemodialysis are typically asymptomatic, making CGM particularly valuable. 4 Hypoglycemia during dialysis occurs in 21-50% of patients despite using dialysate containing 100-150 mg/dL glucose. 4, 6

Preventive Measures

• Provide intradialytic carbohydrate-rich snacks for patients who experience hypoglycemia during dialysis. 6
• Consider using a basal-plus approach rather than basal-bolus insulin regimens to minimize hypoglycemia risk. 1
• Both plasma glucose and insulin levels decrease during passage through the dialyzer, regardless of dialysate glucose concentration. 7

Alternative Glycemic Markers

Do not rely solely on HbA1c for glycemic management in hemodialysis patients, as it underestimates mean glucose levels and correlates poorly with actual glycemic control. 2, 1 HbA1c is falsely low due to anemia, erythropoietin-stimulating agents, reduced erythrocyte lifespan from uremia, and erythrocyte lysis during hemodialysis. 2

CGM-derived metrics (mean glucose, glucose management indicator [GMI], and time-in-range) are more reliable than HbA1c in dialysis patients. 2, 1 Glycated albumin has been proposed as a better indicator but lacks widespread availability. 2

Critical Pitfalls to Avoid

• Never use aggressive glycemic targets that increase hypoglycemia risk without mortality benefit in this population. 1
• Avoid relying on symptoms to detect hypoglycemia, as all hemodialysis-related hypoglycemic episodes are asymptomatic. 4
• Do not assume dialysate glucose concentration prevents hypoglycemia - sensor glucose levels can fall well below dialysate glucose concentration in 50% of patients. 4
• Hypoglycemia-related hospitalizations before dialysis initiation strongly predict higher mortality after starting dialysis. 1