Diagnosis of diabetes using the oral glucose tolerance testBMJ 2009; 339 doi: https://doi.org/10.1136/bmj.b4354 (Published 28 October 2009) Cite this as: BMJ 2009;339:b4354
All rapid responses
Olabi and Bhopal raise various issues regarding the inaccuracy of
using of the oral glucose tolerance test (OGTT) for the diagnosis of
diabetes.1 They appropriately cite that genetics, body composition,
ethnicity and gender are among the factors which may account for some of
the variation in the prevalence of diabetes across populations. However,
more disconcerting is the fact that there are currently two definitions
for impaired fasting glycaemia (IFG), as an indication for OGTT.2,3 The
World health organisation (WHO) and the International Diabetes Federation
(IDF) define IFG as fasting plasma glucose levels 6.1 - 6.9 mmol/l,
whereas the American Diabetes Association (ADA) recommends a range of 5.6
- 6.9 mmol/l.
We assessed the outcome of OGTT in 266 obese patients with fasting
plasma glucose between 5.6 and 6.0 (i.e. the difference between the two
definitions). We found that 62% of these patients had abnormal OGTT
results (19% had diabetes and 43% had IGT).
We agree that clinicians must be confident that the key tests for
diagnosing diabetes or impaired glucose tolerance are accurate. However,
we believe that irrespective of which test is used in the future to
diagnose diabetes, whether OGTT or glycated haemoglobin, agreement among
professional bodies is paramount in avoiding any confusion about the
diagnosis of a disease which has significant and lifelong consequences.
Raashda Sulaiman, SpR in Chemical Pathology
Royal Wolverhampton Hospitals NHS Trust,
Wolverhampton WV10 0QP
Mourad Labib, Consultant Chemical Pathologist,
The Dudley Group of Hospitals NHS Foundation Trust,
Dudley, West Midlands DY1 2HQ
1.Olabi B, Bhopal R. Diagnosis of diabetes using the oral glucose
tolerance test. BMJ 2009;339:b4354. (5 December.)
2 American Diabetes Association. The Expert Committee on the
Diagnosis and Classification of Diabetes Mellitus. Follow-up report on the
diagnosis of diabetes mellitus. Diabetes Care 2003;26:3160-7.
3 WHO. Definition and diagnosis of diabetes mellitus and intermediate
hyperglycaemia: report of a WHO/IDF consultation. WHO, 2006.
Competing interests: No competing interests