HbA1C what we dont know

How informative is Glycosylated Hemoglobin Estimation?? Ans:-This blood test is useful to estimate the average control of blood glucose in the previous 90 days. The blood can be drawn any time of the day. If done by a reliable laboratory it provides important information which blood glucose   estimation cannot provide ideally it should be done at every three monthly follow up visit In addition to blood glucose estimation. The two values together give vital information.

For example: Condition 1) Normal  HbA1c high FBS  interpretation will be:-- overall control over the last 90 days was satisfactory  and it is possible that either control was lost  recently or the patient  did not take the previous evening’s  medication One should verify  before increasing  the dosage of medication  under   such circumstances.

Condition 2:  High HbA1c, normal fasting and post lunch blood glucose: Interpretation will be :- In such situation her   post prandial values need to be checked.  Some people take small working  lunch but a large dinner their  post dinner blood  glucose values  are much higher than post lunch blood glucose values

Condition 3 :-High  HbA1c   but normal FBG & PPBG: Interpretation ::  Her/ his blood glucose overall  control over th last 90 days    was poor and control was achieved in the last  few days. If such results are obtained in pre employment check up one should suspect the possibility   of a diabetic   person hastily achieving control through   treatment   from a private doctor so as to pass the pre employment medical examination .

Therefore, estimation of  HbA1c has become an integral part of routine laboratory  tests in day to  day  management of diabetes . HbA1c  has very good correlation with  micro vascular complications  of diabetes. However it has certain limitations  which precludes it’s  widespread use in our  country  non availability  of standardization.

What do we mean by Principles  of HbA1c  test ??  :

In circulating blood glucose is constantly  getting attached to hemoglobin through non enzymatic process. This attachment is irreversible and percentage of hemoglobin in glycated form out of total hemoglobin in circulation depends upon blood  glucose level. Thus in  a diabetic  patient  depending on the degree of hyperglycemia over previous 90 days  higher percentage of hemoglobin  is glycated as  compared  to normal  percentage of hemoglobin is glycated as  compared  to normal  persons in who around  4% to 6%  of hemoglobin is glycated,. In  other words   HbA1c levels are in the range of 4% to 6% in non diabetic normal persons . Thus  a diabetic  with persistent  poor control  will have  very high  level of HbA1c  while a diabetic  with persistent  tight blood glucose  control will have his HbA1c values  near those  for normal  persons. All diabetics should  aim to keep their HbA1c  constantly between 6.5% to 7% .