PRACTICAL: RANDOM BLOOD SUGAR (RBS)
A random blood sugar (RBS) test measures the amount of sugar (glucose) in the
bloodstream at any given time, regardless of when the individual last ate. It is a
simple and rapid test commonly used to assess blood glucose levels and screen for
disorders of glucose metabolism such as diabetes mellitus.
Glucose is the primary and preferred energy source for the human body. It is
derived from carbohydrates in food and transported into cells via specialized glucose
transport proteins, including glucose transporters (GLUTs) and sodium-glucose
cotransporters (SGLTs). It is central to energy consumption, and all body cells can
utilize glucose to produce ATP, the energy currency required for cellular functions,
muscle contractions, brain activity etc., Blood glucose concentration is tightly
regulated by several hormones including: insulin, glucagon, somatostatin, amylin,
GIP, GLP-1, epinephrine, cortisol, growth hormone. In healthy adults without
diabetes, normal blood sugar (glucose) levels usually range between 4.0 – 7.8
mmol/L (72–140 mg/dL).
Hypoglycemia can be defined as the occurrence of a wide variety of symptoms in
association with a plasma glucose concentration of 3.9mmol/L (70 mg/dL) or less.
Can lead to blurred vision, difficulty concentrating, confusion, slurred speech,
numbness or tingling sensations and drowsiness. Severe or prolonged hypoglycemia
can deprive the brain of its essential glucose supply, potentially resulting in seizures,
coma and may lead to death. Hyperglycemia is the technical term for elevated
blood sugar (glucose) generally defined as: >7.8 mmol/L (>140mg/dL) and >11.1
mmol/L (200 mg/dL) two hours after meals, often seen in people who have diabetes
that isn’t well controlled. Common symptoms include: increased thirst, frequent
urination, unexplained weight loss, fatigue, increased appetite.
Blood glucose levels can be determined using a biochemistry analyzer or a portable
hand held glucometer.
Test Principle:
A glucometer works by using enzymatic biosensors to detect glucose in a blood
sample, which then triggers a measurable signal, typically an electrical current or a
color change. The test strip contains enzymes like glucose oxidase or glucose
dehydrogenase that react with glucose, producing a chemical by-product
proportional to the glucose concentration. This by-product is them converted into an
electrical signal by a transducer (electrochemistry) or causes a color change that is
measured by reflectance photometry. The glucometer converts the detected signal
into a numerical blood glucose value, which is displayed on the screen.
Materials
Glucometer Cotton wool
Test strips Spirit
Lancet (a very short, fine Sharps container
needle) Dustbin
Gloves
Finger-prick tests are typically the best way to monitor your blood glucose levels.
Plentiful capillaries in the fingertips make them bleed well and reliably produce
samples for testing. Blood samples taken from a fingertip will show blood sugar level
changes faster than those taken from other areas of the body due to the increased
blood flow in the fingertips.
Procedure
1. Prepare your supplies.
2. Insert the test strip to turn on the glucometer.
3. Clean the third or ring finger and collect a drop of capillary blood sample using
appropriate safety measures and procedures.
4. Wipe off the first drop.
5. Discard off the sharps appropriately.
6. Place the edge of the test strip on the drop of blood - the blood gets into the
test strip via capillary sucking. Make sure that the blood drop has saturated
the test confirmation window (detection zone) to ensure the correct result. Do
not use damaged test strips or test strips changed in any way. Ensure not to
have blood spill over the test strip.
7. Clean the remaining blood on the finger using a clean and dry cotton wool.
8. Take the glucose reading and record the results.
9. After testing completed, remove the test strip from the meter.
10. Discard the strip into a sharps container.
11. Remove the gloves and dispose them off in dustbin with appropriate bin liner.
Note: Observing safety precautions when performing a random blood sugar test is
crucial to prevent infections, ensure accurate readings and avoid injuries from
sharps. Key measures include maintaining strict hygiene, never sharing needles, no
recapping of lancets and safely disposing of lancets and test strips in the sharps
containers.
Questions
1. Briefly explain why the ring or middle fingers are preferred choices for needle
prick test?
2. Which part of the finger is the preferred puncture site, and why?
3. Why is the first drop of blood usually wiped away before taking a sample?
4. What potential issue does or vigorously squeezing the finger create?
5. What is the impact of an expired test strip on a glucometer reading?
6. Why do the human body and specific cells require tight regulation of blood
glucose levels?
7. How do physiological stressors (e.g., severe illness, acute trauma) impact
blood glucose levels in non-diabetic patients?
