Monday, February 2, 2009

Diagnosing diabetes using an A1c

This article made top headlines today: Doctors are beginning to use the A1c test to diagnose type 2 diabetes.

I think it makes sense to use this test as a diagnostic test. After all, the usual diagnostic tests for diabetes only tell you what the person's blood glucose is doing at that time, while an A1c test effectively tells you what it's been doing for the past three months.

In fact, this makes so much sense that I can't help but wonder why doctors just now thought of it!

Of course, the article fails to mention that A1c test results tend to vary in what they actually mean, depending on the lab your doctor's office uses. The same A1c from two different labs may translate into different average blood glucose levels, in other words. So a 7 from one lab might be the same as a 6 from another — a fact the article ignored with its blanket statement, "People who don't have diabetes typically have about a 6 or less reading."

What I found especially interesting about the article is that it mentions there are no clear standards for diagnosing type 2 diabetes. What exactly does that mean? That we don't understand the disease as well as we would like? That the whole "prediabetic" thing is a bunch of hooey? Or does it simply mean that the fasting blood glucose and the oral glucose tolerance test simply aren't very good at indicating whether a person has type 2 diabetes — and therefore why the A1c test is needed to help diagnose the condition?

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