Hi

Dr Ananya Mandal, MD wrote:

Blood Sugar Glucose Measurement

Imbalances of blood sugar are common among patients of diabetes mellitus. Diabetes indicates persistently high blood sugar that may cause damage to various organs like the kidney, heart, small arteries and the eyes (retina).

Diabetics are also prone to sudden drops in blood sugar called hypoglycaemia. To monitory these fluctuations blood sugar measurement is vital in diabetic individuals.

Some of the considerations in blood glucose measurement include:

Sample

Glucose can be measured in whole blood or serum (ie, plasma). Earlier blood glucose was measured in whole blood. Nowadays serum is extracted from blood and glucose is measured in the serum. Whole blood and serum blood glucose is often different. Red blood cells have higher concentration of protein than serum and serum has higher water content and more dissolved glucose than whole blood. To obtain blood glucose in serum from figures in whole blood, it is multiplied by 1.15.

Blood is collected from a vein (usually in the crook of the arm). The blood sample is collected into vacuum tubes. Blood sample needs to be collected from a different arm other than the one where there is the intravenous line to prevent confusion of the results with the intravenous fluids. After meals the levels in the veins are somewhat lower than capillary or arterial blood. The estimate is by about 10%.

The surrounding temperature before processing affects blood glucose level estimation. At refrigerator temperatures, glucose remains relatively stable for several hours in a blood sample. At room temperature (25 °C), a loss of 1 to 2% of total glucose per hour is seen in whole blood samples.

If the blood is allowed to clot the glucose in the sample gets metabolized by the blood cells unless the cells are separated. If there are higher numbers of red or white blood cells there is excessive glycolysis in the sample with substantial reduction of glucose level. This occurs if the sample is not processed immediately and leads to a faulty result.

To prevent such losses blood samples are collected in Fluoride tubes (ie, gray-top) since fluoride inhibits glycolysis. Red-top serum separator tubes can also be used for samples after being centrifuged isolating the serum from cells.

Timing of the test

Blood sugar is measured at various points of time to give an idea about the body’s blood glucose regulation system. The primary test is the fasting blood glucose. (FBG). This is measured after overnight fasting. Blood glucose normally is lowest early in the morning after 6 to 8 hours of fasting overnight.

Two hours post prandial blood glucose or PPG is the next common test. After a carbohydrate rich, full meal, two hours are allowed to elapse before blood is taken again for estimation of glucose. This test gives an estimation of glucose handling by the body.

Other tests include oral glucose tolerance test (OGTT) and intravenous glucose tolerance test (IVGTT) wherein a fixed amount of glucose is administered orally or intravenously respectively and repeated blood sugar tests are performed to check on the body’s glucose handling.

Another important test is the glycosylated haemoglobin (HbA1C). This test gives an idea about fluctuations of glucose in blood over a period of last three months.

Blood glucose can also be self-monitored by the patient using meters or hand help portable monitors. Blood glucose is co-ordinated with urine glucose test as well.

Methods of blood sugar measurement

The earlier method used to measure blood sugar is a chemical method that exploits the ''nonspecific reducing'' property of glucose in a reaction with an indicator substance that changes color when reduced. There are other blood compounds like urea that also have reducing properties, this technique may yield faulty results. The method currently in use, utilizes enzymes specific to glucose and is less likely to yield errors of this kind.For more plz read at following links.

Regards

http://clinical.diabetesjournals.org/content/25/2/43.full

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2769957/

https://en.wikipedia.org/wiki/Glucose_meter

http://www.news-medical.net/health/Blood-Sugar-Glucose-Measurement.aspx

Dear Colleague,

In addition to the excellent answer of Dr B;Bhagavan, I should like, first, to mention that presently all the methods of glucose determination in clinics (strips, glucometers and so on)are built on glucose oxydase action. So the chemical basis being the same, the results cannot be influenced by the nature of the determination method. Other methods are under investigation but in laboratory only. Second, the glucose level being a result of many external and internal interactions (income and utilization + regulation by hormonal actions) it is normal that the site from which the tested aliquot was obtained influences the results of the analysis. The moment when you take veinous, capillar or heart blood after the death has also a significative importance. Our first data (in rats) have shown that "central" blood glucose level may be much higher than pripheric capillar samples one and that these levels change with the delay after death: peripheral glucose concentration decreases (utilization without new arterial apport) whereas the cebtral one may increase during hours). That probablyought to be verified and taken into account. So it is useful to mention the conditions of taking the samples and providing the analysis to be credible and to unformize these conditions to have liable possibilities of comparison.

Good luck and best wishes,

V.Coulic

Thank you professor..Ali A R Aldallal  and Prof..Véry Coulic for your clarification. Really very informative and opt answers for my question sir..Thank you so much sir...

Dear Boopalan,

Another factor to consider is the stress level of the animals. When one anesthetizes a rat, it is stressful, expect glucose values to be higher, sometimes much higher. I think that I would get a final tail stick glucose value prior to sacrificing, because the value after sacrificing may be difficult to interpret. Alternatively, collect blood from a tail stick into a capillary tube, spin it down and obtain the serum or plasma and use that in your glucose oxidase method. I us an Analox glucose analyzer which needs only 10 ul of serum or plasma, or even 5 ul, so to e this would be preferable than to try to get

So main thing is practicality and what kind of data your after.  Blood glucose strips can have a high variability in measuring glucose (think SD). Just measure it yourself, you'll see how the value changes.  Therefore, its is not very precise in estimating real absolute glucose concentration so it has poor reproducibility.  So its a "quick and dirty" glucose concentration estimate. However, it is useful observing a trend...e.g., its the BG glucose trending up, or is it trending down in your experiment.

In contrast, the glucose oxidase method is more precise and reproducible. Your SD between replicate measurements should be less.

Parcial response in http://www.nature.com/articles/srep21752.  MM section.

Regards

Dear Colleague,

I should like to add to my previous answer that alloxan induced diabetes is not considered as very liable because it trends to spontaneous correction within several days. Morefraquently used and closer to Diabetes type 1 is Streptozotocin induced diabetes. Only ACTH can reverse it in significant doses. You will find necessary information in Pubned and Internet

Good luck!

V Coulic

This link maybe helpful

https://www.ncbi.nlm.nih.gov/books/NBK248/

regards

Please I want to ask if my experimental design depend on measuring glucose and lipid profile, how can I do this as glucose require only 8 hours of fasting, while lipid profile needs 12 hours of fasting, to optain accurate results. Thanks