Serum Fructosamine in Assessment of Diabetic Control and Relation to Thyroid Function

Summary

Measurement of serum fructosamine using a Roche kit is a simple and reliable method for the estimation of glycated serum proteins. The value of serum fructosamine can be affected by hyperglycemia in diabetics and an abnormal turnover rate of serum protein in patients with thyroid dysfunction. We measured the serum fructosamine level in 18 normal control subjects, 71 diabetics (8 IDDM, 63 NIDDM) and 46 non-diabetic untreated patients with thyroid dysfunction (28 hyperthyroidism, 18 hypothyroidism). The serum fructosamine level was significantly increased in the diabetics compared with the normal control subjects (3.84 ± 0.15 mmol/l vs 2.58 ± 0.08; mean ± SE, P < 0.01). The serum fructosamine levelin the diabetics was positively correlated with the fasting plasma glucose and HbA1c level, showing the highest correlation with fasting plasma glucose at 2 weeks before and with the HbA1c level at 2 weeks after serum fructosamine measurement. In the patients with thyroid dysfunction, the serum fructosamine level in hyperthyroidism (2.08 ± 0.03 mmol/l) and hypothyroidism (3.11 ± 0.07 mmol/l) were significantly lower (P < 0.001) and higher (P < 0.001) than the normal control subjects (2.58 ± 0.08 mmol/l), respectively. Furthermore, the serum fructosamine level in these patients was negatively correlated with the level of serum thyroid hormones such as T3 (P < 0.001) and T4 (P < 0.001). It is concluded that measurement of serum fructosamine is clinically useful for the evaluation of shorter-term glycemic control in diabetics, but its level for diabetic patients with thyroid dysfunction must be cautiously interpreted.

Key-Words

Serum Fructosamine - Thyroid Function - Hyperthyroidism - Hypothyroidism