Diabetes is diagnosed on the basis of history (ie polyuria, polydipsia and
unexplained weight loss) PLUS
- a random venous plasma glucose concentration >= 11.1 mmol/l
- OR a fasting plasma glucose concentration >= 7.0 mmol/l (whole blood
>= 6.1 mmol/l)
- OR 2 hour plasma glucose concentration >= 11.1 mmol/l 2 hours after
75g anhydrous glucose in an oral glucose tolerance test (OGTT)
With no symptoms diagnosis should not be based on a single glucose determination
but requires confirmatory plasma venous determination. At least one
additional glucose test result on another day with a value in the diabetic range
is essential, either fasting, from a random sample or from the two hour post
glucose load (1,2). If the fasting or random values are not diagnostic the 2-hour
value should be used.
These diagnostic criteria for diagnosing and classifying diabetes were applied
to the management of diabetes in the UK from June 1st 2000 (1). The new criteria
included lowering the threshold for diagnosing diabetes from a fasting glucose
level of 7.8 mmol/l to 7.0 mmol/l.
It should be noted that children usually present with severe symptoms
and diagnosis should then be based on a single raised blood glucose result,
as above. Immediate referral to a Paediatric Diabetes Team should not be delayed.
A diagnosis should never be made on the basis of glycosuria or a stick reading
of a finger prick blood glucose alone, although such tests may be useful for
HbA1c in the diagnosis of diabetes mellitus (3)
- CMO's Update, 26, May 2000.
- MeReC Briefing 2004; 25:1-8.
(2011).Use of Glycated Haemoglobin (HbA1c) in the Diagnosis of Diabetes Mellitus
(Abbreviated Report of a WHO Consultation). WHO/NMH/CHP/CPM/11.1
- Diabetes UK. New diagnostic criteria for diabetes (Jan 2011) - Use of Haemoglobin
A1c (HbA1c) in the diagnosis of diabetes mellitus in the UK