The precise level of blood glucose for the definition of diabetes has been revised a number of times and is likely to be revised again.
Classical symptoms of hyperglycaemia – polyuria (excessive urination); polydipsia (thirst); nocturia (nocturnal urination); lethargy; weight loss diagnosis is generally ‘clear-cut’
The use of random blood glucose testing is first line approach when investigating for diabetes. Tests need to be repeated on subsequent days to confirm diagnosis if no other symptoms are present.
Criteria for diagnosis of diabetes mellitus:
1. Classical symptoms plus a random plasma glucose concentration > 11.1mmol/l (200mg/dL)
2. Fasting plasma glucose > 7.0mmol/l (fasting is no food for > 8 hours)
3. 2 hour plasma glucose greater than 11.1mmol/l during oral glucose tolerance test (OGTT)
Criteria for diagnosis of impaired glucose tolerance:
• fasting plasma glucose < 7.0mmol/l • 2 hour post glucose >7.8 and < 11.1mmol/l during OGTTRecommendations that HbAic of ≥6.5% be used as diagnostic cut off.