Alberta Precision Laboratories

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Organization:

Alberta Precision Laboratories

Test Name/Synonym:

Glucose Tolerance, 2 Hours (GTT 2 HOUR) (Synonym: GTT, GTT2, 2 HOUR GTT)

Ordering Alert:

This test requires a pre-booked appointment Cannot be collected by Mobile Collection Service.

Note:

Body weight required for patients less than 18 years of age.
Calgary Zone patients weighing less than 42 kg (92 pounds) must be referred to the Glenbrook PSC with advanced notice. (Testing performed Monday – Friday)

Collection Alert:

Patient must be fasting 8 – 16 hours before collection.

LABID (Connect Care):

LAB169

Specimen Type:

Blood

Primary Container:

Edmonton Base Lab: GOLD SST
All other sites: MINT LIHEP PST

Alternate Containers:

Edmonton Base Lab: MINT LIHEP PST
All other sites: GOLD SST

Minimum Collection Volume:

Edmonton Base Lab: 1 mL serum or plasma
All other sites: 0.2 mL plasma or serum

Specimen Collection Requirements:

Specimens are collected at fasting & 2 hours after 75g glucose drink is administered. Drink must be consumed within 5 minutes.
Record glucose amount (grams) and time taken for patient to consume drink.

If patient vomits, testing is cancelled.

Test Resources:

	Glucose Tolerance, 2 Hour Patient Instructions
	Microcollection Minimum Whole Blood Volumes – Calgary Zone

Stability and Storage:

Store refrigerated

Method and Interpretation of Results:

Glucose, Fasting (mmol/L)	Glucose, 2 hours after 75g glucose drink (mmol/L)	2018 Diabetes Canada Guideline Interpretation
Greater than or equal to 7.0		Meets criteria for diagnosis of diabetes mellitus
	Greater than or equal to 11.0	Meets criteria for diagnosis of diabetes mellitus
6.1 – 6.9	Less than 7.8	Meets criteria for diagnosis of impaired fasting glucose (prediabetes)
Less than 6.1	7.8 – 11.0	Meets criteria for diagnosis of impaired fasting glucose (prediabetes)
6.1 – 6.9	7.8 – 11.0	Meets criteria for diagnosis of impaired fasting glucose and impaired glucose tolerance (prediabetes)

Testing Schedule:

Monday - Friday

Critical Value:

Age	Critical Value (mmol/L)
Fasting Specimen
0 up to 72 hours	Less than 2.0 or greater than 24.9 mmol/L
72 hours up to unspecified	Less than 2.6 or greater than 24.9 mmol/L
2 Hour Specimen
0 up to unspecified	Less than 2.6 or greater than 24.9 mmol/L

Testing Area:

Biochemistry

Performing Site:

Calgary Zone	Alberta Children’s Hospital Banff – Mineral Springs Hospital Canmore General Hospital Claresholm General Hospital Diagnostic and Scientific Centre Didsbury District Health Services Foothills Medical Centre High River General Hospital Oilfields General Hospital Peter Lougheed Centre Rockyview General Hospital South Health Campus Strathmore District Health Services Vulcan Community Health Centre
Central Zone	Camrose – St. Mary’s Hospital CCMHB - Ponoka Daysland Health Centre Drayton Valley Hospital and Care Centre Drumheller Health Centre Hanna Health Centre Innisfail Health Centre Killam Health Centre Lacombe Hospital and Care Centre Lamont Health Centre Olds Hospital and Care Centre Ponoka Hospital and Care Centre Provost Health Centre Red Deer Regional Hospital Centre Rimbey Hospital and Care Centre Rocky Mountain House Health Centre Stettler Hospital and Care Centre St. Joseph’s General Hospital - Vegreville Sundre Hospital and Care Centre Three Hills Health Centre Tofield Health Centre Two Hills Health Centre Vermillion Healthcare Centre Viking Health Centre Wainwright Health Centre Wetaskiwin Hospital and Care Centre
Edmonton Zone	Edmonton Base Lab University of Alberta Hospital
North Zone	Athabasca Healthcare Centre Barrhead Healthcare Centre Beaverlodge Municipal Hospital Bonnyville Healthcare Centre Boyle Healthcare Centre Central Peace Health Complex – Spirit River Cold Lake Healthcare Centre Edson Healthcare Centre Elk Point Healthcare Centre Fairview Health Complex Fox Creek Healthcare Centre George McDougall – Smoky Lake Healthcare Centre Grande Cache Community Health Complex Grande Prairie Regional Hospital Grimshaw / Berwyn and District Community Health Centre High Prairie Health Complex Hinton Healthcare Centre Manning Community Health Centre Mayerthorpe Healthcare Centre Northern Lights Regional Health Centre – Fort McMurray Northwest Health Centre – High Level Peace River Community Health Centre Sacred Heart Community Health Centre – McLennan Seton Healthcare Centre - Jasper Slave Lake Healthcare Centre St. Theresa General Hospital – Fort Vermillion St. Therese – St. Paul Healthcare Centre Valleyview Health Centre Wabasca / Desmarais Healthcare Centre Westlock Healthcare Centre Whitecourt Healthcare Centre William J. Cadzow – Lac La Biche Healthcare Centre
South Zone	Bow Island Health Centre Brooks Health Centre Cardston Health Centre Chinook Regional Hospital Crowsnest Pass Health Centre Fort Macleod Health Centre Medicine Hat Regional Hospital Oyen – Big Country Hospital Pincher Creek Health Centre Raymond Health Centre Taber Health Centre

Additional Test Information:

For clinical interpretation, see Diabetes Canada | Clinical Practice Guidelines

Last Updated On:

Wednesday, August 6, 2025