Although glucose level is the contributing factor and diagnostic marker for type 2 diabetes, there is an imperative need to look “beyond glucose” and to seek additional biomarkers that could better predict the risk for diabetes as well its diagnosis with accurate precision.

Human serum albumin is one of the most abundant plasma proteins that readily undergoes glycation, thus glycated albumin has been suggested as an additional marker for monitoring glycemic status in people with type 2 diabetes.

Scientists at the National Chemical Laboratory (Pune, India) collected blood samples from a diabetes specialized clinic as well as healthy controls. Diagnostic parameters, including fasting blood glucose, HbA1c, oral glucose tolerance test, postprandial blood sugar, lipids, urea, creatinine, and microalbumin were measured. Equal volumes of two plasma samples with similar HbA1c (deviation of less than 0.2%) were pooled, and three such pooled plasma in each group were used for mass spectrometric technical triplicate analysis.

The team used high resolution accurate mass spectrometry (HR/AM) which has paved the way for the fragment ion library that was used for quantification of glycated peptides of albumin in the context of diabetes. Glycation is a non-enzymatic chemical reaction between glucose and proteins leading to formation of advanced glycation end products (AGEs), which have been implicated in the pathogenesis of type 2 diabetes and its complications. All samples were analyzed on hybrid quadruple Q Exactive Hybrid Quadrupole-Orbitrap Mass Spectrometer (Thermo Scientific; Waltham, MA, USA).

Muthuswamy Balasubramanyam, PhD, senior author of the study said, “While earlier studies quantified only Amadori-modified lysine (AML) modifications, our study in addition characterized the carboxymethyl-lysine (CML) and carboxyethyl-lysine (CEL) modified peptides of albumin and this is an important advancement as CML and CEL are the predominant AGEs, constituting up to 80% of total AGEs. The association of CML modified peptides of albumin with prediabetes, diabetes, and microalbuminuria is a clinically relevant and therapeutically important finding.” The study was published originally online on August 1, 2015, in the journal Molecular Cell Proteomics.

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