Magazine
Laboratory Screening of Diabetes
Prof. Upali ILLANGASEKERA
Diabetes is considered to be one of the commonest diseases to affect
mankind causing a significant number of deaths and debility. It is so
common that it causes a death every five seconds some where in the world
and each second a new patient is diagnosed. There are nearly 300 million
patients with diabetes worldwide and in Sri Lanka it could be about a
million.
Testing your sugar level |
Common symptoms of diabetes include loss of weight, thirst, passage
of large amounts of urine and skin problems. The complications of
diabetes include heart attacks, strokes, ulcers in the legs,
amputations, kidney failure and loss of vision. An important feature in
this illness is that in nearly 50% of those affected by it have no
symptoms and by the time the diagnosis is made some of these patients
would be exhibiting the above complications.
Therefore it is crucial to identify these patients who do not exhibit
symptoms of diabetes so that the dreaded complications could be
prevented.
The purpose of this letter is to discuss some important aspects of
screening for diabetes to commemorate the World Diabetes Day which falls
on the 14th of November. This is the birthday of Sir Frederick Banting,
the co-discoverer of insulin, the life saving drug used in patients with
Diabetes.
There are in fact two types of screening in diabetes. It could be
"Screening for Diabetes" and "Screening in Diabetes".
Screening 'for' diabetes
This indicates the use of tests for the diagnosis of undiagnosed
diabetes. A large number of people who don't have symptoms of diabetes
are not bothered to test for it as they consider themselves healthy or
indifferent to their own health. Suitable tests are available for
screening and it could be carried out in the whole population (universal
screening) or screening when the opportunity arises (opportunistic
screening) or screening in high risk individuals (high risk screening).
Universal screening is expensive and impracticable to carry out and
is therefore not practised even in highly developed countries such as
the United States. However opportunistic screening is more practicable
and is the type of screening carried out when a person presents to a
doctor or a hospital for any other reason.
The screening done at medical examinations for insurance policies and
employment purposes too could be considered as types of opportunistic
screening. However the type of screening that brings about a diagnosis
in a large number of patients is high risk screening where a person who
is at a high risk of developing diabetes is screened. Those who are at
high risk of developing diabetes in the future are shown below.
1. Those with a family history of diabetes
2. High blood pressure and high cholesterol values
3. Sedentary occupations
4. Over weight persons
5. Those who have been fat (more than 3.5 kg) and those who have been
very thin (less than 2.5 kgs) at birth.
6. Those on diabetes producing medications.
The presence of a family history confers a very high risk for the
development of diabetes. Family history includes parents, children,
siblings and paternal and maternal uncles and aunts. The risk of a child
developing diabetes if both parents have the condition is nearly 60%
whereas if only one parent is affected it is about 40%. It is therefore
advised that all those who are more than 30 years old with a family
history of diabetes should be screened at least once a year.
High blood pressure (hypertension) and high cholesterol are very
common among Sri Lankans. Previous studies have revealed that nearly 40%
of adults over the age of 30 years have high blood pressure (There is
some recent evidence to indicate that those who are just below the blood
pressure levels designated as high blood pressure called
"pre-hypertension" too are prone to develop diabetes).
Daily excercise and the right food to keep fit and healthy |
Most white collar occupations in our country are sedentary. There is
hardly any exercise carried out by these workers, a fair number of whom
become diabetic.
Even though the problem of over weight (measured by an index called
body mass index) is not common in Sri Lanka a significant number of our
people have increase of weight around their waists and this is called
'central obesity'. Central obesity is caused by the deposition of excess
amounts of fat around the waist.
A simple measurement of the waist could identify these people. A
nonelastic tape held around the waist at the most protuberant part of
the abdomen indicates waist size. In a healthy male it should be less
than 90 cms whereas in a female it should be less that 80 cms.
All those who have waist measurements above this range should
therefore undergo testing for diabetes.
Birth weight of individuals have a profound affect on health. New
born babies whose birth weight is less than 2.5 kgs or more than 3.5 kgs
are more prone to develop conditions such as diabetes and heart disease
in adult life. Since at present most people have their birth weight
records all those at the above ranges should be tested for diabetes.
The overuse of drugs such a predisolone which could cause diabetes is
rampant in Sri Lanka. This drug is used in the treatment of conditions
such as asthma, arthritis and skin conditions. All those who have taken
these drugs on a long-term basis should be tested for diabetes.
Tests used in screening for diabetes
The commonest test used is the fasting blood sugar where a sample of
blood is taken after an overnight fast of 8 to 10 hours. An abnormal
result does not necessarily indicate the presence of diabetes until the
person is retested three days later. The other tests used include a
blood test done 2 hours after ingesting some glucose. This test is done
in certain special situations. A urine test for sugar is of no value in
the diagnosis of diabetes.
Screening 'in' diabetes
Gestational Diabetes |
Screening in diabetes means identification of complications of
diabetes. The patient may or may not exhibit the symptoms of
complications. Of these complications now a days nearly all patients are
screened for high cholesterol, kidney disease and eye disease at the
time of diagnosis of diabetes. High cholesterol is diagnosed by a blood
test called the 'lipid profile' and the likelihood of kidney involvement
by a simple urine test called 'microalbumin'. Eye screening is carried
out by an instrument called the ophthalmoscope.
In addition during the course of time some patients need screening
for unsuspected heart disease, kidney disease and disease of blood
vessels.
A very close association exists between diabetes and heart disease.
It is mandatory that all patients with diabetes are screened for heart
disease under the following circumstances.
1. A typical chest pain. A patient may not exhibit the typical
symptoms of a heart attack but instead would manifest with other types
of chest pain.
2. Difficulty in breathing.
3. High cholesterol and high blood pressure.
4. Diabetes of more than 5 years duration.
5. An abnormal ECG.
The tests used include ECHO cardiography, stress ECG and some times
even coronary angiography where a dye is injected into the blood vessels
supplying the heart muscle (called coronary arteries) and an X ray taken
to identify which vessels are blocked.
Screening for kidney disease is indicated in situations where there
is protein in the urine and uncontrolled blood pressure. The tests
include urine tests, blood tests as well as X rays and scans. Tests used
to determine the condition of the blood vessels supplying the legs
include Doppler and arteriography whereas in the case of the heart a dye
is injected into the blood vessels of the legs to determine their
potency.
The writer is President, Diabetes Association of Sri Lanka (Kandy
Branch)
|