Imperial Collage Healthcare

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Glucose (Blood)

Test Background
Glucose serves as the main source of energy for the body and its levels are tightly regulated by a variety of hormones, of which insulin is perhaps the most well known. The absence of insulin (type 1 diabetes mellitus (DM)) or insensitivity/resistance to its activity (type 2 DM) are characterised by hyperglycaemic states that initiate micro- and macro-vascular disease. Hypoglycaemia is a common presentation of (neonatal) inborn error of metabolism, insulinoma, factitious or over-administration of exogenous insulin, states of cachexia and hypopituitarism.

Clinical Indications
Diagnosis of DM, impaired glucose tolerance or insulin resistance
Monitoring of established DM
Diagnosis of metabolic disorders, endocrine neoplasia and hypopituitarism

Reference Range

Over 4 weeks old, fasting   3-6 mmol/L

Over 4 weeks old, random  3.0-7.8 mmol/L

Less than 4 weeks old        2.2-7.8 mmol/L 

Sample Required
Fluoride oxalate (grey top)

Sample Volume
0.5 mL

Turnaround Time
1 day


2x random glucose >11.1 mmol/L: diagnostic of DM.
2x fasting glucose >7.0 mmol/L: diagnostic of DM.
Oral glucose tolerance test (OGTT) 2h postprandial >11.1 mmol/L: diagnostic of DM.
Fasting glucose <7.0 mmol/L AND 2h postprandial OGTT 7.8-11.1 mmol/L: impaired glucose tolerance.
Fasting glucose 6.1-6.9 mmol/L (AND if available 2h OGTT <7.8 mmol/L): impaired fasting glycaemia
Fasting glucose 5.5-6.9 mmol/L: consider referral into the NHS Diabetes prevention programme.

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