Fructosamine

A high fructosamine level means that the average blood glucose over the previous 2 to 3 weeks has been elevated. In general, the higher the fructosamine level, the higher the average blood glucose level. Monitoring the trend of values may be more important than a single high value.

A trend from a normal to a high fructosamine level may indicate that glucose control is not adequate. This, however, does not pinpoint the cause. A review and adjustment to diet and/or medication may be required to help get glucose under control. Illness and significant stress can also temporarily raise blood glucose levels so these factors may also be taken into account when interpreting results.

Low fructosamine levels in the blood typically indicate a lower average blood glucose concentration over the preceding two to three weeks, reflecting a shorter-term glycemic control compared to hemoglobin A1c, which represents a three-month average. This decrease in fructosamine can be seen in individuals with hypoglycemia or those who have achieved better glycemic control due to changes in diet, exercise, or diabetes medication. However, it's important to note that fructosamine levels can also be affected by other factors independent of glucose levels. For instance, lower fructosamine levels can occur in conditions associated with a rapid turnover of proteins, such as hyperthyroidism, or in situations leading to a reduction in serum proteins like malnutrition or severe liver disease. Therefore, while low fructosamine levels can suggest good blood sugar control, they must be interpreted in the context of the individual's overall health, medical history, and concurrent conditions.

Fructosamine is found in the plasma of both normal and diabetic individuals. “Fructosamine” is the term used to describe proteins that have been glycated (ie, are derivatives of the nonenzymatic reaction product of glucose and albumin). It has been advocated as an alternative test to hemoglobin A1c for the monitoring of long-term diabetic control. Fructosamine and hemoglobin A1c do not measure exactly the same thing, since fructosamine has a shorter half-life and appears to be more sensitive to short-term variations in glucose levels; however, this is not necessarily a disadvantage. Fructosamine is clearly superior in patients with abnormal hemoglobins because of the interference of abnormal hemoglobins in the anion-exchange chromatography methods for Hb A1c. Published reference interval for apparently healthy subjects between age 20 and 60 is 205−285 μmol/L and in a poorly-controlled diabetic population is 228−563 μmol/L with a mean of 396 μmol/L.