A1c is now routinely recommended for diagnosis of diabetes mellitus. However, I feel A1c variation owes a lot to patient & technology specific factors. So can u generally share our experience for diagnosing DM with A1c?
Regards
Hi Sikandar,
I cannot speak to the use of HbA1C kits as I have not used them myself, but the current literature has identified important variables based on the kits used. For the full list, refer to the following paper:
Article Pitfalls in Hemoglobin A1c Measurement: When Results may be Misleading
However, I did want to comment on the patient-specific factors to which you referred. Generally speaking, measuring the A1C is a great way to estimate circulating glucose levels over the past 7-8 weeks; this diagnostic window is defined by the half-life of red blood cells. In contrast, measuring a patient blood glucose is highly dependent on the time of day, their fed/fasted status, stress level, etc... For this reason, two separate recordings of fasting blood glucose are required to make a diagnosis, whereas only a single measurement of A1C (>6.5) is needed to diagnose a patient with diabetes mellitus.
You implied that exceptions exist, which is true, but is primarily based on the half-life of red blood cells. For example, patients with various forms of hemolytic anemia (G6PDH, Sickle cell, etc...) have a falsely reduced level of A1C. Other patient variables that reduce A1C include pregnancy, splenomegaly, and certain medications.
In contrast, patients receiving a blood transfusion are likely to have a higher-than-expected A1C (though this is probably based on the hyperglycemic transfusion media). The list continues, with uremia, hypertriglyceridemia, asplenia, etc...
So clearly, interpreting an A1C measurement for any patient requires context. However, lacking better alternatives, it is a great way to determine whether patients are at high risk of developing end-organ complications due to chronically-elevated hyperglycemia.
Refer to this great write-up for more information on A1C measurement variability.
Hyperglycemia in diabetes starts to attenuate body tissues a considerably long time (3-9 years) before diabetes is manifested clinically. One of these impacts of hyperglycemia is through protein glycation.
Measurement of glycated serum albumin (or known as fructosamine) was used as a biomarker for assessing glycemic control in diabetes. I was among those who tried to test its performance as a diagnostic test for T2DM. However, it fails to give an enough sensitivity to be a diagnostic test!
Elevated HbA1c, on the contrast, was confirmed to be diagnostic& both ADA& WHO have recommended that.
Although HbA1c can reflect the average plasma glucose in the past 6-8 weeks, when fructosamine level reflects the average glycemia over the past 21 days only, but still the use of HbA1c is limited by a few things! Hemoglobinopathies are the most important.
If you are intending to rely on A1c in your diagnoses, you have to be sure that no such kind of blood disorders are present so that you can interpret your results correctly.
At this time you have to use a dependable and trusted commercial kit, it will give you good results if you follow the manufacturer instructions correctly. I do not want to be an "advertiser", but from my experience kits from companies like Human, Germany gave me reliable& nice results.
Best Wishes
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