DIAGNOSIS
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Indications for SCREENING |
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India has the dubious distinction of having the largest number of people with diabetes. Recent studies have shown that for every person known to have diabetes, there are more than 2 people who have diabetes but are unaware of it.
In fact, many persons with Type II diabetes already show the presence of the long term complications associated with diabetes at the time of diagnosis. It is now widely accepted that if diabetes is detect3d early and adequate steps are taken, it may be possible to significantly delay the onset and progression of these complications. Thus, this is all the more reason to try and diagnose the onset of diabetes at the earliest.
Although diabetes does have its typical signs and symptoms, many people do not exhibit these "typical" signs and symptoms even though they have diabetes.
All those who complain of symptoms or show signs commonly associated with diabetes must have a test for diabetes, if feasible, all persons over the age of 30 years should undergo an annual test to rule out the presence of diabetes.
A negative test for diabetes does NOT mean that the person will never get diabetes. It only means that the person does not have diabetes at the time of testing.
Persons at high risk MUST undergo testing when they present for medical attention for whatever reason, and if negative, must have a regular annual check, thereafter.
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| Persons at HIGH RISK for diabetes: | |
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All persons manifesting any of the following signs and symptoms: polyuria, polydipsia,
polyphagia, weight loss inspite of adequate food intake, undue tiredness and fatigue, tingling or
numbness in the extremities, burning feet, generalised pruritus, pruritus vulvae, balanitis,delayed
wound healing, impotency, premature cataracts, visual disturbances.
All persons with a family history of diabetes.
All obese patients, especially those with central obesity, waist-hip (W-H) ratio, approx. >0.95 in men and >0.85 in women, and/or a Body Mass Index (BMI) >25.
All adult patients with tuberculosis, including atypical presentations, recurrent infections, non-healing ulcers.
Patients with atherosclerosis and its complications, especially those with premature acrovascular disease.
All patients with high blood pressure and lipid abnormalities.
All women with a bad obstetric history, recurrent fetal wastage, and those who give birth to large weight babies.
Persons who were large weight babies; very low birth weight babies may also be redisposed to diabetes.
Persons who show an acute rise in the blood glucose levels at time of physical (myocardial infarction, cerebrovascular accidents, acute infections, trauma, etc.) or mental stress.
Persons taking drugs which are known to increase blood glucose levels like steroids, thiazide diuretics, oral contraceptives, beta-blockers, phenytoin sodium, etc. Ideally,
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| All persons over the age of 30 years should undergo an annual test for the presence of diabetes |
METHOD
The diagnosis of diabetes MUST be based on blood glucose estimations.
Urine glucose testing must NOT be used to diagnose diabetes.
True blood glucose should be estimated using enzymatic methods like the Glucose Oxidase method.
It should be clear whether the blood glucose estimation has been carried out on capillary blood, whole venous blood, or on venous plasma.
A fasting venous whole blood glucose of more than 110 mg% (venous plasma glucose > 126 mg%) OR a random venous whole blood glucose level of more than 180 mg%, (venous plasma
glucose > 200 mg%), confirmed on repeat testing, in a patient with characteristic sign and symptoms of diabetes, is diagnostic.
Doing a Glucose Tolerance Test in a known diabetic is NOT necessary.
In all other persons, a Glucose Tolerance Test must be carried out in order to exclude diabetes.
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| GLUCOSE TOLERANCE TEST (GTT) |
Procedure
The person to be tested must be on their usual diet, exercise and routine schedule for at least 3 days prior to the test.
The test should be carried out in the morning after fasting for 8 hours; blood is collected in the fasting state.
75 gms of anhydrous glucose (for children the dose is 1.75 gms of glucose per kg of body weight upto a maximum of 75 gms.) is given orally; this may be dissolved in water to avoid nausea; it may be flavoured with a little lime to make it more palatable; the glucose solution should be ingested within 4-5 minutes. If glucose monohydrate ( which is the form of glucose most commonly available in the market) is used, 82.5 gms. must be administered.
The person must rest throughout the test.
Smoking should not be permitted during the test.
A note must be made of any factor which may interfere with the correct interpretation of the test (e.g. medications, inactivity, infections, etc.)
Blood is collected 2 hours after glucose ingestion.
The results are interpreted according to the W.H.O. criteria
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| CRITERIA FOR DIAGNOSIS |
| Table |
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Glucose Concentration (mg/100ml) |
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Whole Blood |
Plasma |
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Venous |
Capillary |
Venous |
| Diabetes Melittus |
Fasting
or |
>/=110 |
>/=110 |
>/=126 |
2 hours post Glucose Load
or both |
>/=180 |
>/=200 |
>/=200 |
| Impaired Glucose Tolerance |
| Fasting(If measured) |
<110 |
<110 |
<126 |
| 2 hours post Glucose Load |
>/=120 & <180 |
>/=140 & <200 |
>/=140 & <200 |
| Impaired Fasting Glycemia |
| Fasting
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>/=100 & <110 |
>/=100 & <110 |
>/=110 & <126 |
| 2 hours PG (If measured) |
<120 |
<140 |
<140 |
I.G.T. : Impaired Glucose Tolerance. Many patients in this category will go on to have diabetes; many I.G.T. patients show associated problems like hypertension, lipid disorders, high uric acid, obesity, etc. which merit treatment; I.G.T. is risk factor for the development of macrovascular disease.
I.F.G. :Impaired fasting glycemia is an entity which has recently been introduced to delineate persons in whom only the fasting blood glucose has been done, but who do not come in the normal or diabetic category. It has been proposed that the diagnosis of diabetes can be made from a fasting blood glucose level only and that it may not be necessary to do a complete GTT. There is still some controversy about this, but the general consensus is that whilst doing only the fassting blood glucose may be sufficient to pinpoint those with diabetes in prevalence studies, it may be beter to confirm this with a complete GT, if feasible.
IFG is felt to reflect a higher average glycemic burden than IGT. It is considered a marker for the development of diabetes and its long term complications.
NORMAL RESULTS
Values not falling within any of the above categories signifies a normal tolerance to glucose.
But,
"A NEGATIVE TEST RESULT ONLY SHOWS THAT THE PATIENT IS NOT A DIABETIC AT THE TIME OF TESTING; IT DOES NOT MEAN THAT HE WILL NEVER DEVELOP DIABETES; SUCH PERSONS MUST HAVE AN ANNUAL CHECK UP".
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| DIAGNOSIS OF GESTATIONAL DIABETES (GDM) |
Gestational diabetes mellitus (GDM) is defined by abnormal glucose tolerance during regnancy; the glucose tolerance test is normal before, and which will usually be normal, after pregnancy.
Gestational diabetes mellitus (GDM) is present in around 3-4% of all pregnancies.
Gestational diabetes mellitus (GDM) can be associated with significant morbidity and ortality in the fetus and newborn.
Thus, it is important for gestational diabetes to be ruled out in all pregnancies.
Ideally, all pregnant women should be tested to rule out gestational diabetes, but if this is not feasible, all high risk patients must undergo the test.
HIGH RISK Patients
Women who had GDM during a previous pregnancy.
Women with a first degree relative who is a diabetic.
Women who gave birth to large weight babies in a previous pregnancy.
Women whose newborn, in a previous pregnancy, showed any complication known to be associated as arising from maternal GDM.
Women who gave birth to still born babies or infants with congenital abnormalities.
Women with a bad obstetric history, including recurrent fetal wastage, hypertension, eclampsia, hydramnios, etc.
Women with repeated or persistent urinary tract infection.
Women manifesting glycosuria during pregnancy.
Women over the age of 30 years.
When Should One test for GDM
The test should be carried out at the time of initial visit and at the start of every trimester; high risk patients may require more frequent testing.
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| SCREENING METHODS for GDM |
Initial screening produce may be done by estimating the fasting glucose levels and the levels 1 hour after an oral dose of 50 gms. of glucose.
This test can be carried out in the fasting stage or at any time; in the latter case, only the one hour blood glucose value is taken into consideration for diagnosis.
Patients with a fasting venous whole blood glucose level of more than 80 mg% (venous plasma glucose more than 90 mg%).
OR
a 1 hour post 50 gms. glucose load venous whole blood glucose value greater than 120 mg/% (venous plasma glucose more than 140 mg%_ require a more comprehensive test.
OR
A "random" venous blood glucose level exceeding 105 mg% (plasma glucose >120 mg%) also merits a more comprehensive test.
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| COMPREHENSIVE TESTS for GDM |
The comprehensive test is the same as described for the diagnosis of diabetes in non pregnant persons. BUT, the criteria differ. In addition to blood glucose levels in the diabetic range, values suggestive of IGT, in a pregnant female, should be taken to be diagnostic of gestational diabetes.
Many centres still utilise the O'Sullivan Criteria.
O'Sullivan Criteria.
In this test, blood is collected in the fasting stage and then at 1, 2 and 3 hours intervals after an oral load of 100 gms of glucose.
The presence of gestational diabetes is diagnosed according to the following criteria:
| | Plasma Glucose
(mg/100ml) | Whole Blood Glucose
(mg/100ml) |
| Fasting | 105 | 90 |
| 1 hour | 190 | 165 |
| 2 hour | 165 | 145 |
| 3hour | 145 | 125 |
Two of the four values must be met to diagnose GDM
Significance of GDM
WOMEN WITH GDM MAY GO ON TO HAVE DIABETES IN LATER LIFE. THEY MUST BE CONSIDERED AS HAVING HIGH RISK FOR THE DEVELOPMENT OF DIABETES AND MUST UNDERGO ANNUAL TESTING |
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