The fructosamine test measures the amount of glycated serum protein in the blood. Serum proteins, primarily albumin, combine (glycate) with glucose (blood sugar) to make glycated serum protein. The amount glycated serum protein is proportional to the amount of glucose in the blood. Serum is the fluid part of blood.

Whereas glucose monitoring is a method of measuring day-to-day glucose control, a fructosamine test can provide an overall view of how a diabetes management plan is working. The test measures a person’s average glucose control for the previous two to three weeks.

The test indicates recent glucose levels because once glucose attaches itself to serum protein, it remains there for the life of the protein, about 14 to 21 days. So even after blood glucose levels have returned to normal, the evidence of high glucose (hyperglycemia) is still detectable as glycated serum protein.

Benefits of a fructosamine test include:

• Confirming other test results. Fructosamine tests can verify self-testing results and blood test results from a physician.
  
  
• Determining the effectiveness of a diabetes management plan. If results are abnormal, a physician can make adjustments to a patient’s exercise plan, diet or medications.
  
  
• Predicting the patient’s risk of developing complications. High levels of glycated serum protein are equivalent to high levels of blood glucose.  Hyperglycemia increases a person’s risk of developing complications such as diseases of the eyes, kidneys, nerves, heart and blood vessels.
  
  
• Encouraging the patient. Good test results can show patients the effectiveness of their decisions on diet, exercise and quitting smoking.

Although fructosamine tests can provide an idea of how well a patient’s diabetes management plan is working, there are disadvantages. Major drawbacks of solely using fructosamine tests include:

• Day-to-day glucose control is not measured. Patients must still rely on regular self-testing with a glucose meter to detect high and low glucose.

• Dosage of medication cannot be adjusted based on results of fructosamine tests. People who are prescribed insulin and certain antidiabetic agents need daily results to prevent low glucose (hypoglycemia) and high glucose.
  
  
• Many factors can cause inaccurate results, such as:
  
• • Vitamin C.
    
  • Hyperlipidemia (high amount of fats in the blood).
    
  • Hemolysis (premature breakdown of the red blood cells).
    
  • Changes in a patient’s protein levels.
    
  • Body weight. Higher weight causes lower test results, and vice versa.
    
  • Liver or kidney disease.
    
  • Hyperthyroidism.
    

• Providing an average of glucose levels can be misleading. Patients whose glucose levels swing erratically from high to low (unstable diabetes) may have a normal or near-normal fructosamine test result even though their glucose is not well controlled.

Although the information provided by a fructosamine test is useful, the test is not widely administered. The glycohemoglobin test (A1C test) is used more commonly to determine the effectiveness of a diabetes management plan. The test measures a person’s average blood glucose level over the past two to three months. Hemoglobin combines with glucose to make glycated hemoglobin. The glycohemoglobin test measures the amount of glycated hemoglobin, which is proportional to the amount of glucose in the blood.

Over the course of a year it would take about 18 fructosamine tests to provide the same information on glucose control as four glycohemoglobin tests. However, situations in which a fructosamine test may be ordered instead of a glycohemoglobin test include:

• When glycated hemoglobin cannot be measured or may not be useful. A fructosamine test may be ordered for patients with blood loss or abnormalities (e.g., hemolytic anemias).
  
  
• When changes in a patient’s diabetes management plan need to be evaluated quickly. The fructosamine test can reveal whether the adjustments are effective after a few weeks rather than months.
  
  
• When a woman is pregnant. Pregnancy can affect glucose by increasing a woman’s need for insulin. Fructosamine tests may be used as a way to frequently monitor and address changing glucose and insulin requirements.
  
  
• When an illness may alter a patient’s glucose levels. Fructosamine tests may be used as a way to frequently monitor and address changing glucose and insulin requirements.
  
  
• When there is a discrepancy between a glycohemoglobin test result and a patient’s record of self-testing results.