What changes in insulin requirements and blood glucose levels can be anticipated in an adult patient with acute kidney injury or end-stage renal disease, and possibly diabetes, when switching from Continuous Renal Replacement Therapy (CRRT) to Hemodialysis (HD)?

Anticipated Insulin and Blood Glucose Changes When Switching from CRRT to Hemodialysis

When transitioning from CRRT to intermittent hemodialysis, expect a significant increase in glycemic variability with higher risk of both hypoglycemia during HD sessions and rebound hyperglycemia afterward, requiring a 25% reduction in basal insulin on dialysis days and more frequent glucose monitoring. 1

Key Metabolic Differences Between CRRT and HD

CRRT provides continuous, gradual solute removal while HD causes abrupt metabolic shifts over 3-4 hours. This fundamental difference drives the glycemic changes you'll observe:

• CRRT maintains relatively stable glucose levels through continuous filtration, whereas HD causes progressive glucose decline during the session with nadir at 3 hours, followed by hyperglycemic rebound 2.5 hours post-dialysis 1
• Insulin clearance patterns differ dramatically: CRRT continuously removes insulin (approximately 10-15g amino acids and 5-10g protein daily), while HD causes acute insulin removal through the dialyzer membrane at each session 1, 2
• The intermittent nature of HD creates a biphasic glucose pattern not seen with CRRT—hypoglycemia risk during and immediately after HD, then hyperglycemia in evening hours 1, 2

Specific Insulin Dose Adjustments Required

Reduce basal insulin by 25% on the day after hemodialysis to prevent hypoglycemia, as total daily insulin requirements decrease by approximately 15% post-HD 3, 4

• For patients with type 1 diabetes, reduce total daily insulin dose by 35-40% when transitioning to HD 3
• For patients with type 2 diabetes, reduce total daily insulin dose by approximately 50% when on HD 3, 4
• The day following HD requires particular attention: basal insulin needs drop by 25% compared to pre-dialysis days due to improved insulin sensitivity and reduced clearance 1, 3

Blood Glucose Pattern Changes to Anticipate

Expect dramatic increases in glycemic variability compared to the relatively stable patterns seen with CRRT:

• During HD sessions: Progressive glucose decline throughout the 3-4 hour treatment, with lowest levels at session end 1
• Post-HD period: Hyperglycemic peak occurring 2.5 hours after dialysis completion, particularly problematic in evening hours 1, 2
• Hypoglycemia occurs in 46-52% of diabetic HD patients, far more frequent than with CRRT 3
• Increased erythrocyte glucose uptake during HD contributes to intradialytic hypoglycemia through mechanisms not present in CRRT 1

Critical Monitoring Strategy

Implement continuous glucose monitoring (CGM) immediately upon transition to detect the asymptomatic hypoglycemia that occurs frequently with intermittent HD but was masked by CRRT's stability 3, 4

• Traditional finger-stick monitoring misses most hypoglycemic episodes during HD 3
• Monitor glucose at minimum: pre-HD, mid-HD (2 hours), end of HD, and 2-3 hours post-HD 3, 4
• HbA1c becomes even less reliable with HD than CRRT due to increased red blood cell turnover; use CGM-derived metrics instead 3, 4

Mechanism-Based Explanation of Changes

The transition from CRRT to HD fundamentally alters glucose homeostasis through several mechanisms:

• Decreased gluconeogenesis: Both modalities impair kidney glucose production, but HD's intermittent nature prevents metabolic adaptation 1
• Impaired insulin clearance: The kidney normally clears 30-80% of insulin; HD removes insulin acutely during sessions but allows accumulation between treatments 1, 3
• Dialysate glucose concentration matters: Most HD uses 100 mg/dL glucose dialysate, creating different osmotic gradients than CRRT replacement fluid 2, 5
• Lactate-glucose interconversion: HD affects lactate metabolism differently than CRRT, with changes in lactate correlating with glucose fluctuations 5

Common Pitfalls to Avoid

Never maintain the same insulin regimen used during CRRT when switching to HD—this guarantees severe hypoglycemia:

• Avoid aggressive glycemic targets (HbA1c <7%); aim for 7-8% in HD patients to prevent dangerous hypoglycemia 3, 4
• Target fasting glucose of 110-130 mg/dL rather than tighter control, as very low HbA1c creates U-shaped mortality curve in HD patients 3, 4
• Don't rely on HbA1c alone: It underestimates mean glucose in dialysis patients due to anemia and shortened RBC lifespan 3, 4
• Watch for "burn-out diabetes": 15-30% of ESKD patients require minimal or no insulin as kidney function declines 1, 3

Practical Day-to-Day Management

On HD days: Reduce morning basal insulin by 25%, monitor glucose hourly during and for 3 hours after HD, provide carbohydrate-rich snack if glucose <100 mg/dL during treatment 3, 4

On non-HD days: May require slightly higher basal insulin doses, but still 15% less than pre-dialysis baseline 3, 4

Evening of HD days: Anticipate hyperglycemic rebound 2-3 hours post-dialysis; may need correction insulin but avoid over-treating given overnight hypoglycemia risk 1, 2