The Role of the Oral Glucose Tolerance Test (OGTT)
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
Notes on Oral Glucose Preparations (OGTT)
- Due 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.
Back to the top of this page