Can a doctor do an oral glucose tolerance test if i recently drank a coke?

Fasting needed : You will need to fasting (without food or drinks) for a minimum of 8 hrs before doing such test. Even if your soda was diet, it still can affect the accuracy if the test.

Need to be Fasting: A sugared soda will make the results of your glucose tolerance test difficult to interpret because it will interfere with how you respond to the glucose challenge you get. Please fast at least 7-8 hours prior to an ogtt.