HbA1c not good for diagnosis of type 2 diabetes mellitus

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Thursday Oct 31, 2013 (foodconsumer.org) -- HbA1c is considered a more reliable indicator for diabetes, but this biomarker may not be able to accurately indicate type 2 diabetes mellitus, according to a new study in BMC Publich Health.    This is so because it is not only glucose that can affect the serum level of HbA1c.

A new study led by Michael EJ Lean from School of Medicine, College of Medical, Veterinary & Life Sciences, University of Glasgow in Glasgow, UK and colleagues shows that smoking was linked to high HbA1c in non-diabetics while high intake of fruit/vegetables was associated with lower serum levels of HbA1c.

High serum levels of HbA1c usually result from reaction between blood sugar (glucose) in the blood and hemoglobin (a typical non-enzymatic browning reaction or Maillard reaction).  Reducing sugar in this case glucose is fairly reactive when meeting proteins like hemoglobin.  High glucose levels as seen in type 2 diabetes mellitus, if not controlled properly can react with hemoglobin to form high levels of HbA1c.  Because HbA1c does not change as quickly as the blood sugar, which can be changed in hours, HbA1c, which is actually an average for a period, is therefore considered a more robust indicator for type 2 diabetes mellitus.

The problem as the current study indicates is that other things can also introduce chemicals like tobacco smoke, which contains more than hundreds if not thousands of different chemicals many of which are reactive.  These chemicals, react with hemoglobin to form advanced glycated hemoglobin and increase HbA1c.  Because of this, HbA1c may not be absolutely a good indicator for type 2 diabetes mellitus.

Fruit/vegetables contain high amounts of antioxidants which can relieve oxidative stress/inflammation induced by environmental risk factors, therefore preventing HbA1c from being increased.

The current study involved participants enrolled in the Scottish Health Surveys 2003 -2010 who did not have diabetes and HbA1c was lower than 6.5%.   HbA1c can be as high as 16% in certain individuals if they have a problem with glucose metabolism. (David Liu)

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