|
Test ID: Glucose
|
|
Glucose
|
|
|
|
Useful For
|
Aid in diagnosis, monitoring and management of different type of diabetes.
|
|
Method name and description
|
UV test
Enzymatic reference method with hexokinase.4,5
Hexokinase catalyzes the phosphorylation of glucose to
glucose‑6‑phosphate by ATP.
HK
Glucose + ATP  G‑6‑P + ADP
Glucose‑6‑phosphate dehydrogenase oxidizes glucose‑6‑phosphate in the
presence of NADP to gluconate‑6‑phosphate. No other carbohydrate is
oxidized. The rate of NADPH formation during the reaction is directly
proportional to the glucose concentration and is measured photometrically.
G‑6‑PDH
G‑6‑P + NADP+ gluconate‑6‑P + NADPH + H+
|
|
Clinical information
|
Glucose is the major carbohydrate present in the peripheral blood The concentration of glucose in blood is controlled within narrow limits by many hormones, the most important of which are produced by the pancreas.
The most frequent cause of hyperglycemia is diabetes mellitus resulting from a deficiency in insulin secretion or action. A number of secondary factors also contribute to elevated blood glucose levels. These include pancreatitis, thyroid dysfunction, renal failure and liver disease.
Hypoglycemia is less frequently observed. A variety of conditions may cause low blood glucose levels such as insulinoma, hypopituitarism or insulin induced hypoglycemia. Glucose measurement in urine is used as a diabetes screening procedure and to aid in the evaluation of glycosuria, to detect renal tubular defects, and in the management of diabetes mellitus. Glucose measurement in cerebrospinal fluid is used for evaluation of meningitis, neoplastic involvement of meninges and other neurological disorders
|
|
|
Specimen type / Specimen volume / Specimen container
|
Specimen type: Serum, Plasma
Minimum volume of sample: 1 mL
Serum: Plain tube (red or yellow top)
Plasma: Li‑heparin and NaF
|
|
Collection instructions / Special Precautions / Timing of collection
|
The stability of glucose in specimens is affected by storage temperature, bacterial contamination, and glycolysis. Plasma or serum samples without preservative (NaF) should be separated from the cells or clot within half an hour of being drawn. When blood is drawn and permitted to clot and to stand uncentrifuged at room temperature, the average decrease in serum glucose is ~7 % in 1 hour (0.28 to 0.56 mmol/L or 5 to 10 mg/dL). This decrease is the result of glycolysis. Glycolysis can be inhibited by collecting the specimen in fluoride tubes.
|
|
Storage and transport instructions
|
Storage: 8 hours at 15 – 25°C
3 days at 15 -25 °C (Fluoride plasma ONLY)
72 hours at 2 – 8°C
Transport: 2-25°C
|
|
Specimen Rejection Criteria
|
Grossly hemolyzed, icteric and lipemic, wrong collection container, insufficient sample.
|
|
|
Biological reference intervals and clinical decision values
|
|
Sample
|
Range (mmol/L)
|
|
Fasting
|
3.3-5.5
|
|
Random
|
Up to 10.9
|
Interpretative Data:
For Fasting and Random Glucose:
Criteria for the diagnosis of diabetes as per American Diabetes Association Guidelines 2017
|
Sample
|
Glucose Range
|
|
Fasting Plasma Glucose
|
≥ 7.0 mmol/L
|
|
Random Plasma Glucose
|
≥ 11.1 mmol/L
|
|
2H PG
|
≥ 11.1 mmol/L or A1c ≥ 6.5% (in patient with classic symptoms of hyperglycemia
|
For 75 g GTT: pregnant women:
Criteria for the diagnosis of diabetes as per American Diabetes Association Guidelines 2017
|
Sample
|
Glucose Range
|
|
Fasting Plasma Glucose
|
≥ 5.1 mmol/L
|
|
1 hour
|
≥ 10.0 mmol/L
|
|
2 hours
|
≥ 8.5 mmol/L
|
For 75 g GTT: adult non-pregnant / male:
Criteria for the diagnosis of diabetes as per American Diabetes Association Guidelines 2017
|
Sample
|
Glucose Range (mmol/L)
|
|
Fasting
|
6.1 – 6.9 is impaired fasting
≥ 7.0 mmol/L or two hours ≥11.1 mmol/L, diagnosis of Diabetes
|
|
2 hours
|
7.8 – 11.1 is impaired glucose tolerance
|
|
|
Turnaround time / Days and times test performed / Specimen retention time
|
Daily (24/7)
Turn-around time:
STAT: 1 hour
Routine: One working day
Specimen retention: 4 days
|
|
|
