Is using WHO criteria for impaired fasting glycaemia appropriate as an indication for OGTT in patients at high risk of developing diabetes?
OBJECTIVE
Impaired fasting glycaemia (IFG) is an indication for oral glucose tolerance test (OGTT). World health organisation and International Diabetes Federation define IFG as fasting plasma glucose (FPG) levels of 6.1–6.9 mmol/l. However, American Diabetes Association still recommends a range of 5.6–6.9 mmol/l as IFG.We performed an audit to assess the outcome of OGTT at various cut offs of FPG levels in patients at high risk of developing diabetes.


METHODS
Laboratory dataon OGTT performed over a period of 1 year in a district general hospital were collected. Patients with FPG levels between 5.6 and 6.9 mmol/l were selected and the outcome was analysed.


RESULTS
Our audit shows that in patients with FPG levels of 5.6–6.0 mmol/l, 19% had diabetes and 43% had impaired glucose tolerance (IGT).


CONCLUSIONS
The percentage of subjects with abnormal OGTT in our study is much higher than that of Decode study [Diabetologica, 42 (1999) 647] (7% diabetes and 29% IGT). However, Decode study had included general population whereas our data were collected from subjects who are at high risk of developing diabetes. We conclude that in these subjects the lower cut off level of 5.6 mmol/l for FPG should be used as an indication for OGTT.
Specialist Registrar in Clinical Chemistry and Metabolic Medicine, Department of Clinical Biochemistry and Molecular Genetics, Russells Hall Hospital, Dudley, West Midlands, UK. Raashda3@aol.com
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Sulaiman
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Labib
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001786:Blood Glucose / Q000378:metabolism*; D003920:Diabetes Mellitus / Q000175:diagnosis*; D005215:Fasting / Q000097:blood; D005260:Female; D018149:Glucose Intolerance / Q000175:diagnosis*; D005951:Glucose Tolerance Test; D006801:Humans; D006943:Hyperglycemia / Q000175:diagnosis*; D008297:Male; D008875:Middle Aged; D011236:Prediabetic State / Q000175:diagnosis; D012016:Reference Values; D012017:Referral and Consultation; D012307:Risk Factors; D014944:World Health Organization
D001786:Blood Glucose