From the Guidelines
Hemodialysis does affect HbA1c measurements, making them less reliable for monitoring glycemic control in patients with end-stage renal disease. According to the most recent and highest quality study, 1, HbA1c levels are typically falsely lowered in hemodialysis patients due to several factors, including reduced red blood cell lifespan, anemia, erythropoietin therapy, blood transfusions, and uremic toxins that interfere with the glycation process. These factors collectively lead to artificially lower HbA1c values that underestimate the actual average blood glucose levels.
Key Factors Affecting HbA1c Measurements
- Reduced red blood cell lifespan (60-90 days versus the normal 120 days) means less time for glycation of hemoglobin to occur
- Anemia, erythropoietin therapy, and blood transfusions can also impact HbA1c levels
- Uremic toxins can interfere with the glycation process, further affecting HbA1c measurements
Recommendations for Monitoring Glycemic Control
For diabetic patients on hemodialysis, alternative methods for monitoring glycemic control are recommended, such as:
- Frequent blood glucose monitoring
- Fructosamine levels
- Glycated albumin measurements These methods provide more accurate assessments over shorter time periods (2-3 weeks) and are less affected by the altered red blood cell dynamics in these patients. As noted in 1, an individualized HbA1c target ranging from <6.5% to <8.0% is recommended for patients with diabetes and CKD not treated with dialysis. However, for patients on hemodialysis, these targets may need to be adjusted based on individual factors and the use of alternative monitoring methods.
From the Research
Hemodialysis and HGA1C
- Hemodialysis can affect HGA1C levels in patients with diabetes, as the correlation between HbA1c and glycemia is weaker in hemodialysis patients due to changes in hemoglobin characteristics and red blood cells half-life 2.
- Studies have shown that hemodialysis can decrease plasma glucose and immunoreactive insulin levels, leading to hyperglycemia in some patients, particularly those with poor glycemic control 3.
- The value of HbA1c as a marker of glycemic control in hemodialysis patients is limited, especially in those with high reticulocyte counts and high weekly erythropoietin doses 4.
- Blood glucose levels can fluctuate during hemodialysis, with a downward trend after the start of dialysis, and hypoglycemia can occur, especially within 1-2 hours of dialysis 5.
- The relationship between HbA1c levels and mortality in hemodialysis patients with diabetes is U-shaped, with increased mortality at both low and high HbA1c levels, suggesting that target HbA1c levels may be higher than those recommended by current guidelines 6.
Factors Affecting HGA1C in Hemodialysis Patients
- Reticulocyte count and weekly erythropoietin dose can independently and inversely affect the correlation between HbA1c and mean plasma glucose 4.
- Hemodialysis-induced changes in plasma glucose and insulin concentrations can lead to hyperglycemia and hypoglycemia 3, 5.
- Diabetes medications and glycemic control can impact HbA1c levels and mortality in hemodialysis patients 6.