Diagnostic Criteria
1. Diabetes symptoms (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 › 6.1mmol/l)
or - two hour plasma glucose concentration › 11.1 mmol/l two hours after 75g anhydrous glucose in an oral glucose tolerance test (OGTT).
2. 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. If the fasting or random values are not diagnostic the two hour value should be used
For more comprehensive Diagnostic Criteria, please click on the link for the WHO document :
WHO Definition and Diagnosis of Diabetes Mellitus and Intermediate Hyperglycaemia
Guidance Notes
Diabetes has important legal and medical implications so the diagnosis must be definite!Do not:
- Base the diagnosis on glycosuria or a finger prick glucose test
- Measurement of HbA1c - this is not used for diagnosis
Do:
- Confirm the blood test by a blood sample sent to the laboratory
- Remember some people will have impaired fasting glucose, this increases their risk of diabetes and CV disease
Patients with impaired fasting glycaemia should:
- Follow the same lifestyle advice as patients with diabetes
- Have an annual fasting blood glucose
- Address CV risk factors aggressively
- Reserve OGTT where an absolute diagnosis of diabetes is needed e.g. for insurance or gestational diabetes. You should discuss the test with the biochemistry department first.
Algorithms