Clinical utility of serum fructosamine in diabetes mellitus compared with hemoglobin A1c.

To evaluate the clinical utility of fructosamine as a mean of monitor glycaemic control, fructosamine and HbA1c were compared in 46 random out-patients visiting a Diabetic Clinic as well as in 25 inpatients admitted to a Diabetes Day Care Unit. In the out-patients, there were a significant correlations between fructosamine and fasting blood glucose (r = 0.75) as well as between fructosamine and HbA1c (r = 0.91). However, when the reference values were considered, interesting differences were found; only 4% of the out-patients showed normal HbA1c values while 39% showed normal fructosamine values. Accordingly, fructosamine and HbA1c evaluate different aspects of glycaemic control. During an admission of 7 days to the Diabetes Day Care Unit no statistical changes in mean blood glucose and fructosamine values occurred. On the other hand, two weeks after discharge from the Unit, not only fructosamine (3.58 +/- 0.16 mmol vs 3.09 +/- 0.08 mmol/l) but also HbA1c (9.52 +/- 0.38% vs 8.33 +/- 0.23%) had improved significantly. Thus HbA1c measures improvements in glycaemic control as early as 3 weeks after changes in treatment. At six weeks after discharge HbA1c (7.63 +/- 0.34%) but not fructosamine (3.02 + 0.14 mmol/l) had improved further. HbA1c is a reliable marker of glycaemic control while the value of fructosamine in clinical practice is unclear.