What causes hypoglycemia (low blood sugar) during dialysis?

Causes of Hypoglycemia During Dialysis

Hypoglycemia during dialysis is primarily caused by decreased gluconeogenesis, impaired insulin clearance, and increased erythrocyte glucose uptake during the dialysis procedure. 1

Multiple Mechanisms of Dialysis-Induced Hypoglycemia

Patients undergoing dialysis, especially those with diabetes, are at high risk for hypoglycemia due to several physiological changes that occur during the procedure:

Primary Mechanisms

1. Decreased renal gluconeogenesis 1

   • The kidney is a major site of glucose production through gluconeogenesis
   • Advanced kidney disease significantly impairs this process

2. Altered insulin metabolism 1

   • Impaired insulin clearance by the kidney
   • Reduced insulin degradation due to uremia
   • Decreased insulin requirements as kidney function declines

3. Dialysis-specific factors 1, 2

   • Increased erythrocyte glucose uptake during hemodialysis
   • Glucose loss to the dialysate, especially with glucose-free dialysate
   • Rapid fluid shifts altering glucose distribution

Additional Contributing Factors

• Impaired counterregulatory hormone responses (cortisol, growth hormone) 1

• Nutritional factors 1, 3

  • Inadequate nutrition before or during dialysis
  • Fasting or reduced food intake around dialysis sessions

• Medication effects 4

  • Prolonged action of insulin and oral hypoglycemic agents
  • Variable exposure to antihyperglycemic medications due to dialysis

Clinical Evidence and Prevalence

Research shows that hypoglycemia during dialysis is common and often asymptomatic. In a study using continuous glucose monitoring, 21% of diabetic patients experienced dialysis-related hypoglycemia (glucose <70 mg/dL) despite using dialysate containing 100-150 mg/dL glucose 2. All these hypoglycemic episodes were asymptomatic, highlighting the importance of monitoring.

Another study demonstrated that asymptomatic hypoglycemia was frequent during hemodialysis when glucose-free dialysis solution was used 5. Adding glucose (90 mg/dL) to the dialysate significantly reduced hypoglycemic episodes.

"Burn-out Diabetes" Phenomenon

An interesting phenomenon called "burn-out diabetes" occurs in approximately 15-30% of patients with end-stage kidney disease (GFR <20 mL/min/1.73 m²) and type 2 diabetes 1. These patients, previously requiring insulin or other antihyperglycemic agents, need less or no medications for glycemic control as kidney disease advances to end-stage.

Dialysate Glucose Concentration

The glucose concentration in the dialysate significantly impacts blood glucose levels during dialysis:

• Glucose-free dialysate increases hypoglycemia risk 5, 6
• Dialysate with 55 mg/dL glucose does not adequately prevent hypoglycemia 6
• Dialysate with 90 mg/dL glucose significantly reduces hypoglycemic episodes 5

Clinical Implications

Hypoglycemia during dialysis carries significant risks:

• Associated with higher mortality after dialysis initiation 3
• Can contribute to cognitive impairment and memory loss 3
• Increases risk of recurrent hypoglycemia 3

Prevention Strategies

To prevent dialysis-induced hypoglycemia:

1. Use dialysate containing adequate glucose (90 mg/dL or higher) 5, 6
2. Adjust insulin and oral hypoglycemic medications before dialysis 4
3. Consider continuous glucose monitoring to detect asymptomatic hypoglycemia 1, 2
4. Ensure adequate nutrition before and after dialysis sessions 1, 3
5. Monitor for hypoglycemia symptoms, recognizing that many episodes may be asymptomatic 2

Hypoglycemia during dialysis represents a significant clinical challenge that requires careful monitoring and management to prevent adverse outcomes and improve patient quality of life.