Detail information about Oral Glucose Tolerance Test.
Here we discuss about the type, indications, contra-indications, precautions, Medication avoiding, Nursing care plan, Risks of OGTT & explain the technique, procedures of doing the test. Thus OGTT is a very important test in medical field. Upgrade your knowledge by reading this. Thanks.
3. Introduction
Glucose is a type of sugar getting from foods we eat and our body
uses it for energy. When we eat carbohydrate such as sugar or
sucrose, our body digest it into glucose, a simple sugar that can
easily be convert into energy. The glucose go straight from the
digestive system into the bloodstream after food is consumed and
digested. But glucose can only enter cells if there is insulin in the
bloodstream too. A glucose tolerance test measures how well the
body’s cells are able to absorb glucose after consuming a specific
amount of sugar. The glucose tolerance test is the most sensitive test
for detecting borderline DM. Glucose tolerance means the ability of
the body to utilize glucose in the circulation. Thus “OGTT” is a
valuable diagnostic aid in diagnosis of DM, insulin resistance,
impaired B-cell functioned relative hypoglycemia and acromegaly.
4. Definition
OGTT means “Oral Glucose Tolerance Test”. It is a
laboratory test to diagnose DM(Diabetes Mellitus).
In this test, glucose is administered to a person
orally and blood glucose levels are measured at
regular interval & interpretation is done between
blood glucose levels with various disorders
associated with carbohydrate metabolism.
5. Types of OGTT
Standard OGTT: A 2 hour 75gm oral glucose
tolerance test is used to tests for diabetes. A
fasting blood sample is collected before to test
glucose level.
I/V glucose tolerance test: Test is taken for
malabsorption patients.
Mini glucose tolerance test: As per WHO, here
2 samples are collected, fasting and 2 hours post
glucose load.
6. Purposes of OGTT
Screening & diagnosis of pre-diabetes or impaired
glucose tolerance.
Screening & diagnosis of type-ll diabetes.
Screening for GDM(Gestational Diabetes Mellitus).
Reactive hypoglycemia.
For detection of B-cell dysfunction.
7. Importance
To find out the ability of the body to cabohydrate
metabolism.
To detect:
1. DM
2. Endocrine function.
3. Renal glycosuria.
4. Alimentary glycosuria.
8. Indications
Patients with family history of diabetes.
Massive obesity.
H/O recurrent infection.
Patients with delayed healing of wounds.
Women who have H/O stillbirth, premature
birth or large baby.
Patients with transient glycosuria or
hyperglycosuria during pregnancy.
9. Contraindications
In proven case of DM.
OGTT is required only id doubtful
cases, it is not recommended for follow
up of patients.
The test should not be carried out in
acutely ill patients.
10. Complications
Infection, if the area is not properly
sterilized before the sample is taken.
Excessive bleeding from the area.
Bruising & swelling.
Feeling light headedness.
11. Precautions
The patients is instructed to eat good carbohydrate diet
for 3 days prior to the test. Diet containing about 35-
50gm of carbohydrate should be taken.
The patient should avoid certain drugs for at least 2
days prior to the test.
The patients should abstain from smoking.
Stressful exercise is to be avoided prior to test.
Exercise is to be avoided also.
12. Medications that should be avoided
Diuretics (thiazide specially)
Corticosteroids
Synthetic estrogen
Phynetoin (Dilantin)
13. Advantages
The OGTT is considered the most effective
way to determine in case of GDM.
Managing sugar level decrease the chances of
baby growing larger for dates.
Managing sugar level may decrease the risk
of intervention in labour & birth.
14. Disadvantages
It is a time consuming test.
Test result may be influenced by stress,
illness or medications.
Blood is less stable after collection due
to improper handling or storage of
blood.
15. Risks of OGTT
These tests have no serious risks. It has some
risks include-
Nausea
Stomach discomfort
Diarrhea
Constipation
Bloating
Headache
16. Patients preparation for OGTT
Normal diet for 3-5days.
Diet containing about 30-50gm of carbohydrate
should be taken on the evening before the test.
Certain should be avoided.
To remain fasting overnight.
Avoid going bathroom before test as urine sample
may be needed.
75gm glucose is to be administered.
Avoid smoking.
18. Explain about the test to the patient.
Instruct the patient to maintain a high carbohydrate diet
for 3 days.
75gm glucose in 250-300ml water is given by mouth.
Venous blood sample & urine samples are collected
either at the end of 2 hours or at half hourly intervals for
2-3 hours.
Inform the patient that she/he may feel a slight
discomfort due to needle puncture.
Plasma glucose is estimated on each sample.
19. Results:
1. Normal OGTT: Serum glucose values in all
samples are within normal range.
2. Impaired glucose tolerance:
Fasting- 5.5- 7 mmol/L
Postprandial glucose- 7.8- 11.1 mmol/L
20. 3. Renal glycosuria: Blood glucose normal but sugar
present is urine.
4. Alimentary glycosuria: Fasting sugar level is normal.
Half/one hourly glucose is threshold. Glucose level rises
and falls sharply.
5. Diabetes criteria:
Blood glucose Normal(mmol/L) DM(mmol/L)
Fasting <5.5 ≥7
2 hrs after
75gm glucose
<7.8 ≥11.1
21. Nursing care plans
Diagnosis Goal Interventions Evaluation
Risk for light
headedness
To prevent
light
headedness
1. Advise to drink more
water & low salt diet.
2. Gibe antiemetic drug.
3. Lying down with closed
eyes in quiet room.
4. Eat healthy diet.
Gradually relief
from light
headedness.
Risk for
infection
To prevent
infection
1. Assess vital sign 4 hourly.
2. Maintenance of aseptic
techniques.
3. Gently handling the
patient.
4. Antibiotic may be given.
Risk of infection
sub-sided.
22. Deficit
knowledge
about OGTT
Provide
information
about OGTT
1. Assess the patients
knowledge about OGTT.
2. Give general knowledge
about OGTT & its
importance.
3. Teach about normal range.
4. Advise to report any
abnormal sign.
Adequate
knowledge
about
OGTT
23. Summery
Though OGTT is time consuming still considered
as the Gold standard for diagnosing Diabetes
Mellitus or rest of the indications are negative.
OGTT evaluates the efficiency of the body to
metabolize glucose. Depending on the baseline
data doctor may recommend changes medication
or treatment. Consulting with health care providers
about any concerns regarding follow up care &
instructions.