Specimen requirement

Plasma

CSF

Spot Fluid

Adult patient:

 Fluoride tube

Minimum blood volume: 2 mL

Adult patient:

 Fluoride tube

Minimum volume: 2 mL

Adult patient:

 Fluoride tube

Minimum volume: 2 mL

Paediatric patient:

Paediatric fluoride tube

Number of vials: 1

Minimum blood volume: 1.3 mL

Paediatric patient:

Paediatric fluoride tube

Number of vials: 1

Minimum volume: 1.3 mL

Paediatric patient:

Paediatric fluoride tube

Number of vials: 1

Minimum volume: 1.3 mL

Authorisation code required

No

24 Hr available service

Yes

Yes

No

Method

Spectrophotometry

Reference interval

Plasma Glucose

1. Fasting plasma glucose (mmol/L):

Result alert limits: < 2.5; > 5.6 mmol/L

Fasting is defined as no caloric intake for at least 8 Hr.

The diagnosis of diabetes mellitus (DM) needs to be confirmed by repeat testing on a separate day or by OGTT.

(Source: modified from Diabetes Care 2010; 33 (Suppl): S62 - 9)

• Plasma glucose concentration in healthy individuals is highly variable due to difference in age, individual’s glucose tolerance & recent carbohydrate intake.
• Diabetes mellitus is diagnosed when fasting plasma glucose is > 7.0 mmol/L confirmed by repeat testing. Impaired fasting glucose is diagnosed when fasting plasma glucose is 5.6 - 6.9 mmol/L.
• Plasma glucose concentration < 2.5 or > 11.1 mmol/L could be associated with potentially fatal hypoglycemic & hyperglycemic crises respectively. Both conditions warrant urgent medical attention and management.

(COCPath Consensus Statement: 8 - 2014)

2. Random plasma glucose (mmol/L):

Result alert limits: < 2.5; > 7.0 mmol/L

• Plasma glucose concentration in healthy individuals is highly variable due to difference in age, individual’s glucose tolerance & recent carbohydrate intake.
• Diabetes mellitus is diagnosed when random plasma glucose is > 11.1 mmol/L with classic symptoms of hyperglycemia or hyperglycemic crisis.
• Plasma glucose concentration < 2.5 or > 11.1 mmol/L could be associated with potentially fatal hypoglycemic & hyperglycemic crises respectively. Both conditions warrant urgent medical attention and management.

(COCPath Consensus Statement: 8 - 2014)

(Source: Diabetes Care 2012; 35(Suppl): S64 - 71)

3. Oral Glucose Tolerance Test (mmol/L):

75 g Oral Glucose Tolerance Test (OGTT):

DM = Diabetes Mellitus
IFG = Impaired Fasting Glucose
IGT = Impaired Glucose Tolerance
*Pre-diabetes = IFG and / or IGT
**DM should be diagnosed if one or more of the OGTT criteria are met.
(Source: American Diabetes Association 2010 Position Statement)

75 g OGTT during pregnancy:

GDM = Gestational Diabetes Mellitus
*GDM should be diagnosed if one or more of the OGTT criteria are met.
**DM in pregnancy should be diagnosed if one or more of the OGTT criteria are met.
(Source: WHO 2013 Diagnostic Criteria and Classification of Hyperglycaemia First Detected in Pregnancy)

CSF Glucose

2.2 - 3.9 mmol/L

(Source: Roberts WL et al. Reference Information for the Clinical Laboratory. In Tietz Textbook of Clinical Chemistry and Molecular Diagnostics, 4th edn. Burtis CA, Ashwood ER and Bruns DE eds. Elsevier Saunders 2006; 2251 - 2318)

Clinical indication

Plasma:

Detection of hyperglycaemia and hypoglycaemia

Diagnosis and as a screening test for diabetes mellitus

Monitoring glycaemic control

CSF:

Aid in diagnosis of meningitis

Result interpretation

Plasma:

See reference interval above.

In patients with fasting plasma glucose levels between 5.6 - 6.9 mmol/L or random plasma glucose levels between 7.8 - 11.0 mmol/L, an oral glucose tolerance test (OGTT) should be performed.

Measurement of uncertainty

See table.

Frequency of measurement

Daily