An OGTT need only be considered to establish a diagnosis of diabetes if blood
glucose values fall into an equivocal range (e.g. FPG >6.0 but <7.0 mmol/L).
An OGTT is not necessary if the diagnostic criteria for diabetes are present
- Perform OGTT after at least 3 days of unrestricted diet (> 150g CHO daily)
- Fast patient overnight (8-14 hours, water allowed) and rest during the test.
- Samples at times other than 0 and 2 hours are not necessary for diagnosis.
- Diagnostic interpretation of OGTT is different in pregnancy
(see Diabetes and Women)
Notes on Oral Glucose Preparations (OGTT)
ue to the variety of different preparations available, The use of LUCOZADE is no longer acceptable.
- 75g Anhydrous Glucose (available on stock order from community pharmacies) is recommended
- If Glucose BP is used instead, then 82.5g should be used
- An alternative is Polycal (see BNF) available in different flavours
- Dose of Polycal = 113 ml in 300ml of water
IFG & IGT have an increased risk of future diabetes
- Advise on healthy eating, regular exercise and avoidance of obesity
- Check FPG annually
- Treat co-existing coronary risk factors aggressively, as are at increased risk of developing cardiovascular disease.