Blood glucose testing

Blood glucose testing
Biochemistry Lab experiment

1. 1





Faculty of Medicine
Biochemistry lab
Blood Sugar Testing
Prepared By :
Diaa Mohammad Srahin .

Supervisor: Dr. Suheir Jabir.

2. 2

BLOOD SUGAR TESTING
Introduction
A blood glucose test measures the amount of a type of sugar, called glucose, in your blood. Glucose comes
from carbohydrate foods. It is the main source of energy used by the body. Glucose is transported from the
intestines or liver to body cells via the bloodstream, and is made available for cell absorption via the
hormone insulin, produced by the body primarily in the pancreas.
Glucose levels are usually lowest in the morning, before the first meal of the day, and rise after meals for
an hour or two by a few millimolar. Blood sugar levels outside the normal range may be an indicator of a
medical condition. A persistently high level is referred to as hyperglycemia; low levels are referred to as
hypoglycemia. Diabetes mellitus is characterized by persistent hyperglycemia from any of several causes,
and is the most prominent disease related to failure of blood sugar regulation. Intake of alcohol causes an
initial surge in blood sugar, and later tends to cause levels to fall. Also, certain drugs can increase or
decrease glucose levels.
The body’s homeostatic mechanism keeps blood glucose levels within a narrow range. It is composed of
several interacting systems, of which hormone regulation is the most important. There are two types of
mutually antagonistic metabolic hormones affecting blood glucose level:
 Catabolic hormones ( such as glucagon, cortisol and catecholamines ), which increase blood glucose
 Anabolic hormones (such as insulin), which decrease blood glucose.
There are several different types of blood glucose tests:
Fasting blood sugar (FBS): measures blood glucose after you have not eaten for at least 8
hours. It is often the first test done to check for prediabetes and diabetes.
2-hour postprandial blood sugar: measures blood glucose exactly 2 hours after you start
eating a meal. This is not a test used to diagnose diabetes. This test is used to see if someone with
diabetes is taking the right amount of insulin with meals.
Random blood sugar (RBS): measures blood glucose regardless of when you last ate.
Several random measurements may be taken throughout the day. Random testing is useful
because glucose levels in healthy people do not vary widely throughout the day. Blood glucose
levels that vary widely may mean a problem. This test is also called a casual blood glucose test.
Oral glucose tolerance test : is used to diagnose prediabetes and diabetes. An oral glucose
tolerance test is a series of blood glucose measurements taken after you drink a sweet liquid that
contains glucose. This test is commonly used to diagnose diabetes that occurs during pregnancy
(gestational diabetes). Women who had high blood sugar levels during pregnancy may have oral
glucose tolerance tests after pregnancy.
Hemoglobin A1c, or glycohemoglobin : measures how much sugar (glucose) is stuck to
red blood cells. This test can be used to diagnose diabetes. It also shows how well your diabetes
has been controlled in the past 2 to 3 months and whether your diabetes medicine needs to be
changed. The result of your A1c test can be used to estimate your average blood sugar level. This is
called your estimated average glucose, or EAG.

3. 3

Objectives
1. To calculate glucose concentration in the unknown sample.
2. To observe concentration of previous sample and compare it with normal value from
scientific references.
Materials
 Spectrophotometer & its components (Light source, Prism, Detector, Photoelectric cell).
 Cuvettes & pipettes & test tubes.
 Monoreagent as a Blank solution.
 Sample (serum).
 Constant temperature incubator set at 37 ͦC.

Methods & Procedures
1- Reagents & samples were Bring to room temperature.
2- Three clean tubes were prepared for our experiment.
3- Materials were put in the labeled tubes as next table shown :
Tubes Blank Serum STD
Working Reagent 1.0 ml 1.0 ml 1.0 ml
serum pool * 10µL *
STD * * 10µL

4- Tubes were mixed and then put 5 minutes at 37 ͦC
5- The absorbance (A) of the sample & the standard was read at 500 nm against the reagent
blank.
6- Finally, calculations were used to determine the concentration of glucose in our sample &
compare it with reference values.

Results
In our experiment, we use Trinder reaction, the glucose is oxidized to D-gluconate
by the glucose oxidase (GOD) with the formation of hydrogen peroxide. In the
presence of peroxidase (POD), a mixture of phenol and 4-aminoantipyrine is
oxidized by hydrogen peroxide, to form a red quinanelmine dye proportional to the
concentration of glucose in the sample.

4. 4


C STD = 100 mg / dL A Sample = 0.757 A STD = 0.474
C glucose =
A Sample
A STD
∗ C STD in mg/ld.
C glucose =
0.757
0.474
∗100

= 159.71 mg/dL.
Discussion
In our experiment we were given an unknown concentration sample with glucose
results and analysis showed the sample to have 159.71 mg/dl glucose which is high
value comparing with normal range for an adult (70 - 105 mg/dL) or children with
normal range (60 – 110 mg/dL). So results show that our patient with hyperglycemia
because blood glucose more than normal range.

Conclusion

1. Metabolic activity of our bodies can be measured using this test.

2. The glucose level in the blood is maintained by diet uptake and regulatory
hormones such as insulin, glucagon, and epinephrine.

3. An abnormal increase in blood glucose level, referred to as hyperglycemia, can
be associated with diabetes mellitus and hyperactivity of thyroid, pituitary or
adrenal glands.

4. An abnormal decrease beyond the fasting level, referred to as hypoglycemia, is
observed in cases of insulin secreting tumors, mixedema, hypopituitarism,
Addison’s disease and conditions interfering with glucose absorption.