Saturday, March 14, 2009

New way assesment of long term Glucose control.

A change from Glycosylated Haemoglobin (HbA1c) to A1C Derived Average glucose(ADAG)

Glycosylated Haemoglobin

Advantage

It’s significance in the treatment of diabetes is commendable,because it shows the glucose status of previous three months. This number tells how well your diet, exercise, and medicine are working.An increase in A1c has been correlated with an increase in the risk of microvascular complications associated with diabetes.

Recommented values set byAmerican Diabetes Association, the Canadian Association of Diabetes and the European Association for the Study of Diabetes are as follows…

HbA1c reported in %.

>7% it iindicates the failure in diabetic treatment

<6.5%>

<6>

Normal person it is <5.4%

Disadvantage

Despite A1c being recognized as the standard measure of glucose control,number of general issues exist with the assay the · Many patients do not understand how to interpret the A1 c value,because it is expressed in % · Accuracy depends on the machines and the standardization method one is following. Though national glyco haemoglobin stanardisation programme have some recommendation in this aspect, it is not been followed all over the world. The above issues led the International federation of clinical chemistry to develop a reference method that is more specific to A1c and could be standardized worldwide.Globally now it’s named as A1 c derived average glucose(ADAG) A1 c derived average glucose(ADAG) or eAG

According to new criteria Hb A1c-derived average glucose or eAG is a new value which is used to assess long-term glucose control. The new system correlates A1c values with long-term control of glucose and is reported in units of mg/dL or mmol/L rather than a
percentage value.

After undergoing several clinical trial The equation identified for the Estimated average glucose is

Average glucose (mg/dL) =28.7 x A1c - 46.7
or
Average glucose (mmol/L) =1.59 x A1c – 2.59

A1c value / Estimated Average Glucose

5%................................97 mg/dL (5.4 mmol/L)
6%................................126 mg/dL (7 mmol/L)
7%................................154 mg/dL (8.5 mmol/L)
8%................................183 mg/dL (10.1 mmol/L)
9%................................212 mg/dL (11.7 mmol/L)
10%..............................240 mg/dL (13.3 mmol/L)
11%..............................269 mg/dL (14.9 mmol/L)
12%..............................298 mg/dL (16.5 mmol/L)

Problems with eAG
Although it improves patient understanding of their long-term glucose control,The equation utilizes a laboratory reported A1c value ,Inaccurate A1c values should be considered when the patient’s recorded self monitoring blood glucose values do not appear to coincide with the measured A1c value


( Certain other Factors which falsely increase A1c include:
· iron deficiency anemia
· patients without a spleen
A number of factors have inconsistent effects on
A1c and include:
· high vitamin C intake
· high vitamin E intake reduce the life span of a red blood cell.6 Factors

which falsely lower A1c include:
· recent acute blood loss
· hemolytic anemia
· chronic blood loss )

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