Fructosamine

The Fructosamine test (also known as glycated serum protein or glycated albumin measurement) estimates glycemic control over approximately one to three weeks, a shorter window than hemoglobin A1c, which integrates glycemia over approximately four to eight weeks. It is indicated when A1c is limited or unreliable (eg, hemoglobin variants, hemolysis, recent blood loss), to evaluate recent adjustments in diabetes therapy, and to monitor diabetes during pregnancy. It serves as a more stable index than single glucose readings, including in patients with abnormal hemoglobins and in children with type 1 diabetes.

Fructosamine measures the concentration of serum proteins that have undergone nonenzymatic glycation in the presence of elevated glucose. Because erythrocytes persist for about 120 days, hemoglobin A1c reflects glycemia across that interval, whereas circulating plasma proteins have a shorter half-life (approximately 14–21 days). Consequently, fructosamine reflects average glycemia over the prior 2–3 weeks. Ongoing diabetes management aims to maintain near-normal glucose to limit complications; laboratory monitoring typically includes intermittent glucose measurements together with longer-interval markers such as fructosamine or hemoglobin A1c. Fasting is not required, as the assay integrates glycemia over weeks rather than capturing an immediate prandial state. Certain factors can lower measured fructosamine, including ascorbic acid and hyperthyroidism.