Determination of Serum Glycated Transferrin (GTf) Levels in Healthy Subjects and Patients with Non-insulin-dependent Diabetes Mellitus (NIDDM)

Abstract

Serum glycated transferrin (GTf) levels were determined in 55 NIDDM patients and 32 healthy controls. To eliminate globulin and albumin, serum was mixed with 40% PEG and centrifuged, and the supernatant was applied to a Blue Sepharose column. Then, GTf and nonGTf in the effluent were separated on an affinity column. Finally, transferrin in these effluents was assayed by the latex agglutination method. After albumin was washed out of the Blue Sepharose column, it was applied to an affinity column and assayed for glycated albumin (GA) and nonGA by ELISA. In NIDDM patients the GTf level (5.6±0.4%) was lower than that of HbA_1c (9.2±0.4%) and GA (17.1±0.9%), and more than twice the level of GTf in controls (2.3±0.1%). As a whole subject group, serum GTf was closely correlated with FPG (r=0.74), HbA_1c (r=0.84) and GA (r=0.85). Because the dlurnal variation of GTf in 5 admitted NIDDM patients before (11.4±0.5-10.7±0.6%) and after (6.7±0.5-5.9±0.4%) rapid glycemic control was negligible, ambient plasma glucose did not influence GTf. When the decline in serum GTf and GA due to rapid glycemic control was compared, t112 for GTf and GA was 6.6 and 9.0 days, respectively. These results suggest that serum GTf reflects the glycemic state as accurately as currently available parameters (FPG, HbAlc and GA), and indicates glycemia over a shorter period than GA.