| 7.1 What is a GTT? |
| 7.2 Can a hypoglycemic person have a 'normal' glucose tolerance test? |
| 7.3 Is the GTT the only method for determining hypoglycemia? |
The oral glucose tolerance test (OGTT/GTT) is a diagnosis method for diabetes and reactive hypoglycemia. In short, the GTT consists of drinking a 100 g glucose solution and measuring the blood glucose (bG) values every hour to get a curve. The form of the curve tells us a lot about the body's sugar metabolism. A normal (2 hour) GTT is sometimes used to diagnose diabetes, however, this is not a common practice anymore. In order to diagnose reactive hypoglycemia an extended (5 or 6 hour) test is necessary, as with some hypoglycemics symptoms won't occur until the 4th or 5th hour. For an even better picture, insulin flows should be measured as well.
These days, the GTT is not considered as *the* instrument for the diagnosis of reactive hypoglycemia anymore, because if one looks at blood glucose (bG) values only quite some healthy persons would be recognized as hypoglycemics too. Therefore, the symptoms experienced during the test and the relief of symptoms after eating are considered just as important as the clinical bG values when diagnosing hypoglycemia. In addition to measuring bG values, insulin levels may be measured as well, to get extra information about the dynamics of your sugar metabolism.
On the web there's a nice collection of information about the
GTT, offering test procedure description, sample curves and criteria:
http://huizen.dds.nl/~hypo,
follow the GTT-link
http://www.healthgate.com/HealthGate/mdx-books/tests/test240.shtml
Yes. There are certain levels of blood sugar which are considered normal (60-120 mg/dl= 3.5-6.5 mmol/l). But some people will have hypoglycemic symptoms even with their lowest numbers in the 'normal' range. The most important aspects of the GTT is if symptoms occur during the test and the symptoms are relieved by eating. This is indicative of hypoglycemia. This is why if you do have a GTT it must be at least a 5 hour test since some people's symptoms don't occur until the 4th hour.
No, if one changes his/her food habits for 3 to 4 weeks to
avoid all sugars, stimulants and heavy starchy foods --pasta,
bread, corn, rice, etc.-- and the symptoms decrease and/or disappear,
it would be a good indication of hypoglycemia. This is especially
true if the person has had all kinds of medical tests and nothing
was found to be wrong. In my opinion, this is a much less stressful
method than the GTT of determining if what you are eating is having
negative effects on your body chemistry.
The most up-to-date copy of this FAQs can always
be obtained from:
Hypoglycemia Homepage Holland: http://huizen.dds.nl/~hypo/faq