Al about GDM & Diabetes

. Tip 13B_ More informants on  HBA1C:  How useful is Glycosylated Hemoglobin Estimation ??

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 :

1)                      Normal  HbA1c high FBS  interpretation overall control over the last 90 days was okay 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.

2)                       High HbA1c  normal fasting  and post lunch blood  glucose Other  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

3)                      High  HbA1c   but normal blood glucose Interpretation overall  control over th last 90 days    was poor and control was achieved in the last  few days. If such  results are obtained in peemployment 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 .

Estimation of  HbA1c has become an integral part of routine laboratory  tests in  day to day management of diabetes in  economically advanced   countries  and also in any centers  in our country. HbA1c  has very good co relation with  micro vascular complications  of diabetes. However  it has certain  limitations  which precludes it’s  widespread use in our  country  such as cost of estimation  and non availability  of standardization.

Q.14 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% .

Haemoglobin A1c  as a diagnostic test for diabetes mellitus . Are we ready for it ? 

Diabetes  mellitus is a metabolic and vascular  disease  with hyperglycemia  and specific micro vascular complications in those who are poorly controlled over  a long term  period as it characteristic features . However  there is no well defined  threshold  level of blood  glucose  beyond which  micro vascular  complications develop and below which  there is a  complete immunity  from complications. Thus fating venous plasma glucose   value of 126 mg %  and tow hours post 75g  oral glucose   load   value of 200 mg%  are somewhat arbitrary diagnostic  values for diabetes  mellitus. At present   for the want   of better diagnostic  test blood glucose  values are used as the only criteria for the diagnosis of diabetes  however these  have certain  limitations.

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