Improved Diabetic Biomarker Testing

EKF Diagnostics has recently introduced the Glycated Serum Protein LiquiColor® test, which provides supplementary information to standard glucose and HbA1c testing. To find out more about the test, and how it can benefit patients, we spoke to Timothy Warlow, Global Product Manager, Central Laboratory, EKF Diagnostics.

TW: Glycated proteins are formed due to a non-enzymatic Maillard reaction between glucose and amino acid residues of proteins. In diabetic patients, elevated blood glucose levels correlate with increased fructosamine formation. Glycated serum proteins (also known as GSP; glycated albumins; fructosamine) are a medium term indicator of diabetic control (2-3 weeks). Because 80-90% of the GSP result is glycated albumin, the results are not affected by conditions or treatments that affect red blood cell lifespan such as hemoglobinopathy, gestational diabetes, anemia, erythropoietin therapy or end stage renal disease, making this test potentially useful as an adjunct to HbA1c in certain situations.

AM: What is the glycation gap, and how can GSP help to overcome this? How does this help diabetic patients?

TW: In typical diabetic patients there is a correlation between their daily blood glucose and their glycated serum protein results. The difference between the actual measured HbA1c concentration and the predicted HbA1c from glycated serum protein is called the glycation gap. This gap has been shown to be a significant predictor of the progression of nephropathy in Type 1 and Type 2 diabetic patients even after adjusting for HbA1c.

TW: Essentially, Fructosamine by the NBT method is non-specific to fructosamines because NBT reacts with various endog¬enous substances of reducing activity such as thiol groups, NADH, and ascorbate. In fact, studies showed that only about half of the reducing activity (Fructos¬amine) was due to specific non-enzymatic glycation of proteins, and the remaining unspecific activity varied from sample to sample. The NBT based Fructosamine assay is, therefore, of limited specificity for the exact mea¬surement of glycated proteins in serum. The LiquiColor GSP assay, on the other hand uses two enzymes to break down samples (Proteinase and FructosamineaseTM) and specifically measure the glycated proteins. This makes the GSP test more reliable and accurate than traditional Fructosamine (NBT) assay.

TW: Currently HbA1c is primarily used to track long term trends in blood glucose for diabetic patients. HbA1c gives a measurement of average blood glucose for the last 3-4 months by measuring the amount of glycation on haemoglobin proteins against the total amount of haemoglobin. However, if a patient suffers from a condition that affects hemoglobin life-span, such as hemoglobinopathy, iron deficiency, end stage renal disease, anemia, uremia, blood loss, pregnancy, or drug treatments like erythropoietin therapy, the HbA1c result can be skewed above or below the actual result. On the contrary, GSP LiquiColor primarily measures glycated albumin (80-90% of the result) which is not affected by these conditions that affect the red blood cell half life. It should be noted though that any protein binding abnormality may affect the GSP result, but these are more rare than the conditions that affect the RBC. 

TW: Currently EKF sells a broad range of open-channel, clinical chemistry tests for diabetic patients including glucose, HbA1c, and a specialty assay for diabetic ketoacidosis called β-Hydroxybutyrate (β-HB). GSP LiquiColor adds depth to this range of tests by filling the information gap between daily blood glucose and HbA1c to give physicians and patients a clearer picture of glycemic control in any situation. EKF is dedicated to providing high-quality, accurate assays that can be used on any open channel chemistry analyser, and GSP LiquiColor helps us continue to achieve this mission.