Performance characteristics and clinical utility of an enzymatic method for the measurement of glycated albumin in plasma

Abstract

Objective: The measurement of plasma glycated albumin is particularly useful in the short-middle term monitoring of glycometabolic control in diabetics. The aim of this work is to evaluate a new enzymatic method for the measurement of glycated albumin in plasma, with particular attention to some selected cases and comparison with other relevant tests (fasting plasma glucose, after glucose load, fructosamine, glycated hemoglobin).Design and methods: We have performed a multicenter study by which sample collection was performed in three different centers (Milano, Padova and Cagliari) and serum samples, frozen at −80°C, were then delivered under dry ice to the centralized laboratory in Milano. Glycated plasma albumin was measured with reagents from Asahi Kasei Pharma (Lucica GA-L enzymatic assay; AKP, Tokyo, Japan) on a Modular P Roche system. Fructosamine was assessed by a Roche method and HbA 1c (measured separately in the three centers on fresh EDTA blood) by DCCT-aligned HPLC systems. We have investigated 50 type 2 diabetics, 26 subjects with gestational diabetes, 35 subjects with thalassemia major, 10 subjects with cirrhosis, 23 patients with end-stage renal disease subjected to dialysis treatment and 32 healthy adult control subjects.Results: The main analytical performance characteristics of the new GA test were the following: (a) the within-assay reproducibility was between 3.0 and 3.9% (in terms of GA% CV, measured on 2 serum pools and 2 control materials at normal and pathological glycated albumin levels); (b) the between-assays reproducibility was from 2.8 to 4.1%; (c) the linearity was tested in the interval between 13 and 36% and found acceptable (r 2 = 0.9932). Concerning the clinical utility of the new test, we have evaluated the relationships between GA, HbA 1c , fructosamine and fasting and post-prandial glucose in several patients, as well as the changes in the abovementioned parameters in a sub-group of type 2 diabetic patients for 18 weeks as they progressed from severe hyperglycemia (HbA 1c ≥10.0%) toward a better glycemic control. The correlations between glycated albumin and HbA 1c were as follows: (a) type 2 diabetics: r 2 = 0.483 (good glycemic control), r 2 = 0.577 (poor control); (b) diabetic patients under dialysis: r 2 = 0.480; (c) liver disease: r 2 = 0.186; (d) transfused non-diabetics with thalassemia: r 2 = 0.004. Glycated albumin, as well as HbA 1c and fructosamine, was of little value in the study of women with gestational diabetes, mainly because of the very limited glucose fluctuations in this particular category of subjects. In 11 type 2 diabetic patients under poor metabolic control, GA was better correlated with fasting plasma glucose then HbA 1c (r 2 = 0.555 vs. 0.291, respectively), and decreased more rapidly than HbA 1c during intensive insulin therapy. Conclusions: The experience we have acquired with the new enzymatic test demonstrates its reproducibility and robustness. We confirm that plasma glycated albumin is better related to fasting plasma glucose with resp...

Diagnostic Significance of Serum Glycated Albumin in Diabetic Dogs

“…Results indicated that the GA enzymatic test proved to be reproducible and robust, as reported in previous studies. 5,7 Moreover, the enzymatic method for GA measurement used in the current study showed high accuracy and reproducibility compared with conventional high-performance liquid chromatography methods. 5 Because this method can use an autoanalyzer, rapid and multiple sample determinations can be performed with ease and convenience.…”

“…2 Fructosamine and GA levels in healthy human patients and human patients with diabetes have been reported to show strong correlation. 6,7 As such, the current study sought to determine whether this correlation would also hold true for dogs and, if so, whether GA could be used as a substitute for fructosamine in dogs. The data indicated that a strong positive correlation exists between fructosamine and GA in dogs.…”

Serum Glycated Albumin as a Glycemic Control Marker in Diabetic Cats

“…2 Fructosamine and GA levels in humans and canines have been reported to show strong correlation. 6,8 The current study suggests that this correlation also holds true for cats and that GA can be used as a substitute for fructosamine in cats. Moreover, serum GA appears to be a useful diagnostic indicator to monitor glycemic control in diabetic cats as an alternative to fructosamine.…”

“…Alternatively, the measurement of GA has been commonly advocated in human diabetic patients and can also provide an index of glycemic control for 1-3 weeks. 3,6,9,10 In addition, a recent study demonstrated that serum GA could substitute for fructosamine with diabetic dogs. 8 As such, the working hypothesis of the current study is that GA could be substituted for fructosamine in diagnosis and treatment monitoring of diabetic cats because GA is a main constituent of fructosamine.…”

Glycemic control in the clinical management of diabetic patients

“…We would particularly like to stress the importance of measuring glycated albumin when interpreting HbA 1c measurements could be hampered by certain pre-analytical conditions (e.g., in cases of chronic hemolytic anemia or hemoglobin variants). It is also worth bearing in mind that glycated albumin can be measured with a specific, robust and reliable enzymatic method that overcomes the limitations of the previous fructosamine test [ 84 ]. It could prove extremely interesting to apply this new test in re-assessing the data used to calculate the glycation gap (GG), proposed for the first time by Cohen et al [ 85 ], whose work proved that GG is reproducible.…”