The person being tested is required to fast for 12 hours, then have a drink with a super-high
sugar content - a disaster plan for someone with hypoglycemia. The blood
is then tested every 30 minutes, for 6 hours. Unfortunately, the test is unreliable as it is frequently done in an inadequate way or is misinterpreted.
The most frequent problems with the GTT are:
The test is run for less than 6 hours - a 3 -hour test certainly can't catch a drop at the 5.5 hour point).