Hi and welcome,
Fasting tests are notoriously unreliable due to some external factors outside our control, such as stress, restless night, the dawn phenomenon (our livers dump glucose in our system to get us ready to face the day). However, a reading of 7 or above is a diabetic reading, but should be followed up with a second test and probably also an HbA1c test. This is the normal diagnostic test for type 2 and is a sort of average of the previous 3 months blood glucose levels.
Relax, have your blood test, go to Brazil and enjoy your time there. 2 weeks won't cause any additional harm. Perhaps just watch what you are eating and try to avoid as much carbohydrate as possible or keep the portions small, no biscuits or cakes etc. and keep fruit to a minimum, and do drink masses of water.
Have a great time!