Low Plasma Albumin Levels Are Associated with Increased Plasma Protein Glycation and HbA1c in Diabetes

Albumin is one of the most abundant plasma proteins and
is heavily
glycated in diabetes. In this study, we have addressed whether variation
in the albumin levels influence glycation of plasma proteins and HbA1c.
The study was performed in three systems: (1) streptozotocin (STZ)-induced
diabetic mice plasma, (2) diabetic clinical plasma, and (3) in vitro
glycated plasma. Diabetic mice and clinical plasma samples were categorized
as diabetic high albumin plasma (DHAP) and diabetic low albumin plasma
(DLAP) on the basis of their albumin levels. For the in vitro experiment,
two albumin levels, high albumin plasma (HAP) and low albumin plasma
(LAP), were created by differential depletion of plasma albumin. Protein
glycation was studied by using a combination of two-dimensional electrophoresis
(2DE), Western blotting, and LC–MSE. In both mice
and clinical experiments, an increased plasma protein glycation was
observed in DLAP than in DHAP. Additionally, plasma albumin levels
were negatively correlated with HbA1c. The in vitro experiment with
differential depletion of albumin mechanistically showed that the
low albumin levels are associated with increased plasma protein glycation
and that albumin competes for glycation with other plasma proteins.