Glycemic Monitoring in Sickle Cell Anemia

Introduction to Glycemic Monitoring

HbA1c cannot be accurately measured in patients with sickle cell disease and should never be used; instead, use fructosamine or plasma glucose measurements for glycemic monitoring and diagnosis, as recommended by the American Diabetes Association 1, 2, 3

Patients with sickle cell disease completely lack HbA, making HbA1c measurement impossible, and the increased red blood cell turnover inherent to sickle cell disease causes falsely low HbA1c readings even when measured 2, 3, 1, 4, 5
The American Diabetes Association explicitly states that in conditions with increased red blood cell turnover such as sickle cell disease, only plasma blood glucose criteria should be used to diagnose diabetes—not HbA1c 1, 6, 4, 5

Fructosamine is the preferred alternative glycemic marker in sickle cell disease because it measures glycated serum proteins rather than hemoglobin, making it unaffected by hemoglobinopathies, as recommended by the American Diabetes Association 2, 3
The American Diabetes Association specifically recommends fructosamine or continuous glucose monitoring (CGM) when an alternative to HbA1c is required 3

For diagnosis specifically, use these plasma glucose criteria: Fasting plasma glucose ≥126 mg/dL, 2-hour plasma glucose during OGTT ≥200 mg/dL, and Random plasma glucose ≥200 mg/dL with symptoms, as recommended by the American Diabetes Association 1, 4, 5, 7
Critical technical requirement: Glucose samples must be spun and separated immediately after collection to prevent falsely low readings from ongoing glycolysis 7
Ensure patients consume at least 150 g of carbohydrate daily for 3 days prior to testing to avoid falsely elevated glucose from carbohydrate restriction 4, 5, 7

Patients with sickle cell trait have different considerations than those with sickle cell disease, and HbA1c can be measured using assays specifically validated to be free from interference with HbS variant 1, 6, 4
Check the National Glycohemoglobin Standardization Program (NGSP) website for updated lists of assays without interference 1, 6
Even with appropriate assays, HbA1c may read approximately 0.3% lower than actual glycemic burden in sickle cell trait carriers 1, 6, 4

Confirm the diagnosis: Determine if the patient has sickle cell disease versus sickle cell trait 2, 3
For sickle cell disease, order fructosamine for ongoing glycemic monitoring and use plasma glucose measurements for diagnosis 3, 1, 4, 5
Consider CGM for comprehensive glycemic assessment in sickle cell disease patients 3

When marked discrepancies exist between any glycemic marker and clinical presentation, suspect assay interference and switch to plasma glucose measurements, as recommended by the American Diabetes Association 1, 6, 7