Diabetes, gestational Diabetes in Pregancy HBA1C role

What  do we mean by GDM?  :Impaired glucose tolerance - which first diagnosed during pregnancy is called gestational diabetes. Prevalence:-It occurs in about 4% of pregnancies in western countries but at India a study done in Chennai and nearby rural area in 2003 , a prevalence of 16.7% ,

Why  it (GDM-impaired carbohydrate metabolisim  ) manifests in preg first time in pregancy is some women? What is etiology? Who is the culprit?? Ans:- GDM results from a)  insulin resistance of pregnancy interacting with b)  beta cell defects. Usually, in cases of GDM  blood glucose is normalized after the delivery which is not true in case of frank GDM . Since significant insulin resistance of pregnancy develops only in third trimester so we should be vigilant more in third trimester. In few women gestational diabetes sets in only in this period. Those who present with glucose intolerance in vary early pregnancy those cases may have pre existing type 1 or type 2 DM . Women having gestational diabetes are at higher risk to develop type 2 DM during later part of their life.

Relevance of HBA1C in our country-cost effective?  Estimation of HbA1c has become an integral part of routine laboratory tests in a day to day management of diabetes in economically advanced countries and also in many 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

Principles of HbA1c test:

We are all aware of the fact that 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 persons in whom 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%.

Following table offers an average blood glucose levels over last 90days for a range of  HbA1c values.

HbA1c in %	Mean blood glucose in mg%
4	60
5	90
6	120
7	150
8	180
9	210
10	240
11	270
12	300
13	330