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Fructosamine is one of the blood tests that can be carried out to measure the blood glucose levels of people who have diabetes. Many people with this disease check their blood glucose levels daily with a home blood sugar meter. Glucose levels can fluctuate throughout the day, however, and doctors frequently wish to know the overall levels of this sugar in the blood. Usually, glucose control is monitored by the hemoglobin a1c test, which determines the blood sugar levels over the past three months. The fructosamine test is an alternate test that determines glucose levels over the previous 2-3 weeks.
The common symptom of different types of diabetes mellitus is excessive levels of the sugar glucose in the blood. Over time, high levels of sugar can severely damage the kidneys, eyes, feet, and cardiovascular system. Therefore, diabetes is treated aggressively, frequently with medication. To determine how well the treatment regimen is working, patients generally check their blood sugar levels at least once a day with a blood sugar meter. It may appear that the levels of glucose are at their ideal levels, but levels may change wildly over the course of the day.
To get a more accurate measurement of the glucose levels over time, doctors frequently perform blood tests to assess the average level of glucose over a period of time. There are two lab tests commonly performed to check blood glucose levels: the hemoglobin a1c test and the fructosamine test. Both measure the amount of glucose that has bound to proteins in the blood, known as glycated proteins. The amount of these proteins is much higher in people that have poor control of their diabetes. Many factors affect the amount of free glucose in the blood, but changes in the levels of glycated proteins happen much more slowly and give much more reproducible readings.
The measurement of fructosamine detects the reaction product of glucose that has bound to the accessible amino group on a protein such as albumin, for example, giving glycated albumin. This test measures glucose levels over the last 2-3 weeks. It is an alternative to the more common hemoglobin a1c test, which can give false readings for patients with blood problems such as hemolytic or sickle cell anemia.
Additional reasons to use this alternate method of hematology include the need to measure blood sugar levels during pregnancy. Because of the mother’s hormonal changes, women with gestational diabetes can have rapid changes in their blood sugar. Doctors wish to monitor these changes much more frequently than with the three month period afforded by the standard test. With the fructosamine test, they check blood sugar levels for the past 2-3 weeks.
Patients frequently undergo changes in their medication. Their blood sugar levels may need to be checked frequently to determine the effect of these changes. The fructosamine test is better suited than the glycated hemoglobin test to measure the rapidly changing glucose levels of such patients.
It is more important to look at trends when evaluating fructosamine levels than it is to analyze the absolute percentage. Levels that decrease suggest that glucose levels are being brought under better control. Increasing levels suggest the opposite. This test is not useful for screening for diabetes. At the lower limit of the test, it is not clear whether a patient has good diabetic control or whether they are free of the disease.