Basic performance of an enzymatic method for glycated albumin and reference range determination

Area of Science:

• Clinical Chemistry
• Diabetes Mellitus Diagnostics
• Glycemic Control Monitoring

Background:

• Glycated albumin (GA) serves as a medium-term glycemic control marker for diabetes.
• GA may offer greater sensitivity to plasma glucose fluctuations compared to hemoglobin A1c.
• Understanding glycation sites and quantification is crucial for accurate GA measurement.

Purpose of the Study:

• To elucidate the binding sites and quantity of fructosyl groups on albumin.
• To identify specific glycation sites quantified by the enzymatic GA assay.
• To evaluate the fundamental performance characteristics of the enzymatic GA method.

Main Methods:

• Enzymatic measurement of glycated albumin (Lucica®GA-L, Asahi Kasei Pharma) using a biochemical autoanalyzer.
• Mass spectrometry was employed to determine molecular weights of purified glycated and non-glycated albumin.
• A cohort of 201 healthy American volunteers underwent oral glucose tolerance testing to establish a reference range.

Main Results:

• The enzymatic method specifically quantifies glycated amino acids on albumin, estimating approximately two per albumin molecule.
• The assay demonstrated good general performance, including sensitivity, specificity, reproducibility, linearity, and minimal interference.
• The reference range for GA% in American adults with normal glucose tolerance was established as 11.9-15.8%; race-based differences were noted.

Conclusions:

• The enzymatic method is specific for glycated amino acids in albumin and exhibits favorable performance.
• The established American reference range for GA is 11.9-15.8%.
• This validated method presents a potentially valuable tool for monitoring diabetes control.