Mohammad
Your observations have been reported on several occasions and some important
issues arise:
1. Using fasting glucose alone to diagnose diabetes will miss many patients
with diabetes or impaired glucose tolerance
2. Guidelines that suggest that Glucose tolerance tests have no place, need
reviewing
3. Guidelines that suggest that only fasting glucose is required for the
diagnosis of diabetes, need reviewing
4. Patients can be classified as diabetic in a fasting state (FPG =/>7
mmol/L) or post challenge (2hr post 75g glucose with plasma glucose =/>11.1
mmol/L). There is an overlap using both criteria, with some patients
fulfilling both criteria, but some patients will only be "fasting" diabetics
and others will only be "post-challenge" diabetics.
5. The importance of GTTs was made clear in the new WHO guidelines, which I
know differ from the ADA.
6. Demand managment of GTTs must occur, and inclusion criteria would be
fasting plasma glucose between 6.1 and 6.9 mmol/L (with the flexibility
related to imprecision and clinical background). Even then some isolated
post challenge (IPC) diabetics would be missed, but the specificity for IPC
falls with fasting glucose below 6.1 mmol/L.
7. The NSFs (National Service Frameworks) for Coronary Heart Disease and
Diabetes have significantly increased the requests for fasting glucose and
follow on GTT- Yet another example of NSFs ignoring the knock on cost for
Pathology (I know that some decision makers read this mailbase!)
regards
martin myers
Preston and Chorley Hospitals
-----Original Message-----
From: Mohammad Al-Jubouri [mailto:[log in to unmask]]
Sent: 21 March 2002 13:58
To: [log in to unmask]
Subject: How to reduce OGTT workload?
Dear all
GTT seems to be ever popular by GPs as our workload is
increasing steadily. In recent paper endorsed by ADA
published in Clin Chem 2002, 48:436-472, OGTT is not
recommended for diagnosis of DM only for diagnosis of
GDM and that fasting glucose must only be used. I have
reviewed 518 GTTs performed over last 3 months by our
dept., where we do not insist on having a fasting
glucose checked before booking and we do not measure
fasting glucose before giving 75 g glucose load. Those
patients with a fasting glucose < 7.0 mmol/L
constituted 87% of the cohort (451 patients), Diabetic
curve (2 h post-load glucose =>11.1 mmol/L) was
detected in 45 patients and impaired glucose tolerance
(2h glucose =>7.8 mmol/L)in 104 patients. Even in 250
patients with a normal fasting glucose (=<5.5 mmol/L,
diabetic curve exhibited by 3 patients and IGT in 37
patients. Can we ignor these GTT findings and depend
solely on a single fasting glucose measurement with
all its inherant analytical, intraindividual and
seasonal variability? can we restrict GTT only to
those with a fasting glucose of 6.0 - 6.9 mmol/L which
will reduce our workload to 130 GTTs only compared to
a total of 518 GTTs? And finally I found only two
thirds of 42 patients with a fasting glucose of 7.0 -
7.9 mmol/L (WHO diabetic level)exhibiting diabetic
curve and the remaining 1/3 showing IGT, which one to
believe the fasting glucose or response to OGTT? All
patients with a fasting glucose of =>8.0 mmol/L (25
patients)exhibited a diabetic curve.
Advice and comments are most welcome.
Mohammad
=====
Dr. M A Al-Jubouri
Consultant Chemical Pathologist
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