Type 2 Diabetes

A. False. A result between 6.1 - 6.9 mmol/L is consistent with impaired fasting glucose. The diagnostic criteria for diabetes (WHO 2006) are as follows:

• Diabetes
• Fasting plasma glucose ≥ 7.0 mmol/L or 2hr plasma glucose* ≥ 11.1 mmol/L
• Impaired glucose tolerance
• Fasting plasma glucose < 7.0 mmol/L and 2hr plasma glucose* ≥ 7.8 and < 11.1 mmol/L
• Impaired fasting glucose
• Fasting plasma glucose 6.1 to 6.9 mmol/L and (if measured) 2hr plasma glucose* < 7.8 mmol/L

* Venous plasma glucose 2 hours after ingestion of 75g oral glucose load.

* If 2hr plasma glucose is not measured, status is uncertain as diabetes or IGT cannot be excluded.

A diagnosis of diabetes can be made on a single result only in the presence of symptoms (polyuria, polydipsia, weight loss). Otherwise 2 results on separate days are required.

B. False. An oral glucose tolerance test (OGTT) is helpful when a fasting plasma glucose result is equivocal (i.e. 6.1 - 6.9 mmol/L). If fasting plasma glucose is between 5.5 and 6.0 an OGTT is also indicated.

• An OGTT involves giving a 75g glucose load following an overnight fast (minimum 10 hours) and measuring plasma glucose immediately before (0 minutes) and at 120 minutes. Anhydrous glucose reconstituted in 250 - 300ml water is recommended although lucozade or maltodextrin preparations are alternatives.
• It is important to note that even if both 0 and 120 minute glucose readings are in the diabetic range a diagnosis of diabetes cannot be made in the absence of symptoms without another positive glucose on a separate day.
• The diagnosis should not be made if the patient is under stress due to an intercurrent illness or medication that can impair blood sugar regulation. Repeat testing will be required once the stress has resolved or controlled.

WHO diagnostic criteria http://www.who.int/diabetes/publications/en/