Glucose, Whole Blood, Serum, Plasma

Sample type

Serum (Red-top tube, gel-barrier tube), Plasma(green-top (lithium heparin) tube) Gray-top (sodium fluoride) tube

Uses

To determine whether or not your blood glucose level is within normal ranges; to screen for, diagnose, and monitor diabetes, and to monitor for the presence of hypoglycaemia (low blood glucose) and hyperglycaemia (high blood glucose)

Precautions

Separate plasma or serum from cells within 45 minutes of collection. Only gray-top tubes may be submitted without centrifugation.

Blood glucose tests fall into several categories, including fasting, random (non-fasting), or post-prandial. Fasting tests are more commonly used to diagnose diabetes.

Fasting test preparation:

For a fasting blood glucose test, you can’t eat or drink anything except water for 8 hours before your test. You may want to schedule a fasting glucose test first thing in the morning, so you don’t have to fast during the day.

Random testing preparation:

Random (non-fasting) blood glucose tests don’t require you to not eat or drink before the test.

Your doctor may have you take several random measurements throughout the day to see how your glucose levels change.

Post-prandial testing preparation:

A test given 2 hours after starting a meal is used to measure postprandial plasma glucose. This test is most often done at home when you have diabetes. It can help you understand if you’re taking the right amount of insulin with meals. You must do this test 2 hours after you start eating a meal. 2-Separate serum or plasma from cells within 45 minutes of collection. Label specimen as serum or lithium heparin plasma

Interfering factors

Physical activity

Exercise or just increasing exertion can lead to altering blood glucose levels:

Physical activity can alter insulin sensitivity for up to 48 hours, resulting in decreased blood sugar levels throughout that time.
Following a brief burst of activity, sugar levels can initially rise. If you are usually active most days, not doing so may result in higher blood sugar levels than usual.
It’s possible that exercising a muscle near where you last injected will cause your insulin to be absorbed faster.

Food, drink and illness

Food, alcohol, tiredness and stress can all impact blood glucose levels.

Many people are surprised to know that protein can affect blood sugar levels, too.

Proteins affect blood sugar levels in the same way that carbohydrates do, but to less of an extent and more slowly than carbohydrates
Sugar levels can be affected by alcohol for up to many hours after you stop drinking.
Stress and illness can also have a big impact on blood sugar levels.

Where do you inject?

Where you inject has an impact on how quickly insulin is absorbed: different regions of your body absorb insulin at different rates. Injecting into lumpy skin has an impact on how insulin is absorbed.

Medication and conditions

Blood glucose levels can be affected by a variety of drugs and medical conditions:

Your sugar levels might be affected by your menstrual cycle in women.
Pregnancy can alter blood glucose goal ranges.
Other medications you’re taking could potentially have an impact on your blood sugar levels.
If you have gastroparesis (delayed stomach emptying), this can lead to unpredictably high blood sugar levels.
Missing a medication dose or injecting at inconvenient times can cause sugar levels to fluctuate.

Pre-analytical errors

Samples unspun or improperly spun (excluding oxalate/NaF); gross hemolysis; gross bacterial contamination; improper labeling
If a patient takes some medication, like insulin, or exercises more than usual, that will have an effect on their level of glucose.

The corrective action

The sample must be rejected and another sample be obtained.
The patients must be given all the instructions they should follow before the test, and before taking the sample, ask the patient, “Did he follow these instructions or not?”

Post-analytical errors

reports sent to the wrong patient
write the wrong name in the report or the wrong results.

The corrective action

communication with patient, apologising for the error, and providing him with the correct report
If the report is not delivered to the patient and this error is discovered, the correct result or the correct name must be written, but if the report is delivered to the patient, you must communicate with him, apologise to him, and tell him that an error has occurred and replace it with the correct report.

Reference Range

Adults (fasting) 70 - 105 mg/dL (3.9 -5.8 mmol/L)

Children 60 - 110 mg/dL (3.33-6.11 mmol/L)

Newborns 40 - 60 mg/dL (2.22 – 3.33 mmol/L)