Many will know that I have had well documented reservations about using HbA1c for diabetes diagnosis in the past, mainly because of its rapid implementation
before obtaining evidence as to whether ageing, ethnicity, anaemia, haemoglobinopathies and other potential limitations were showstopper issues in its use. However, I agree with Graham and Ian here that this paper arrives at a predictable conclusion simply
by making the GTT the Gold Standard. In doing so it is not surprising that one of the two components of the GTT (FPG) picks up fewer patients and a different test entirely (HbA1c) picks up different ones.
I still have my concerns about using HbA1c for diagnosis, but I doubt I will be quoting this paper to support them.
Best wishes
Eric
From: Clinical biochemistry discussion list [mailto:[log in to unmask]]
On Behalf Of Ian Young
Sent: Thursday, January 05, 2017 3:53 PM
To: [log in to unmask]
Subject: Re: Inaccurate diabetes screening hits the news!
I agree completely with Graham’s analysis. Using a GTT as a diagnostic reference will inevitably lead to these findings, and ignores
the many limitations of the test………
No clinical biochemist involved, so far as I can see.
Best wishes
Ian
From: Clinical biochemistry discussion list [mailto:[log in to unmask]]
On Behalf Of Graham Jones
Sent: 05 January 2017 12:45
To: [log in to unmask]
Subject: Re: Inaccurate diabetes screening hits the news!
Colleagues,
I have to express major concerns with this paper - which frankly leave me staggered!
The idea that on oral glucose tolerance test is a physiological gold standard for pre-diabetes seems somewhat ludicrous. This is not to deny its role as a definitional test, just to recognise its
limitations. To then compare other "sub gold standard" tests with OGTT and find they are different is (a) not a surprise and (b) indeed expected. The cutoffs for the various tests are selected to predict some of the complications of chronic hyperglycaemia
but I am surprised that OGTT is taken as the gold standard in this setting (although I will confess to not have followed the pre-diabetes literature very closely). I am even more surprised that the paper does not recognise this reference standard issue as
a problem (see Strengths and limitations). With the outcome data, the best that can be said is that pre-diabetes detected by other methods may respond differently to those detected by OGTT. It is not possible to say whether they may respond better or worse.
Yes all the tests are imperfect, yes they will detect different populations, but neither of these say they do not work.
A moment of self reflection says I am turning into a GOM (grumpy old man). Is there a test for that?
With good wished and in the interest of debate,
Graham
From: Clinical biochemistry discussion list <[log in to unmask]>
on behalf of Jonathan Middle <[log in to unmask]>
Sent: Thursday, 5 January 2017 8:31 PM
To: [log in to unmask]
Subject: Inaccurate diabetes screening hits the news!
Hi
This metanalysis - http://www.bmj.com/content/356/bmj.i6538
has hit the news today - http://www.bbc.co.uk/news/health-38506713
HNY to all!
Jonathan
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