HbA1c reflects glycation of haemoglobin within which cell?

Correct answer: C. Red blood cells

• A. Platelets contain no haemoglobin and survive about 8 to 10 days.
• B. Lymphocytes contain no haemoglobin.
• C. CORRECT. Glucose binds non-enzymatically and irreversibly to haemoglobin within erythrocytes. Because red cells live approximately 120 days, HbA1c reports the average blood glucose over roughly the preceding 2 to 3 months, weighted toward the most recent month.
• D. Neutrophils do not contain haemoglobin and their lifespan is measured in hours to days.

Note: Clinically important limitation: anything that shortens red cell lifespan FALSELY LOWERS HbA1c — haemolytic anaemia, sickle cell disease, recent blood loss, pregnancy, chronic kidney disease with erythropoietin therapy. Conversely, iron deficiency anaemia can falsely raise it. In these patients use fructosamine or continuous glucose monitoring instead. Reference points: normal under 5.7%, prediabetes 5.7–6.4%, diabetes 6.5% and above, and a common treatment target under 7%.