2 hour glucose test

I made a post a couple weeks ago talking about how I couldn’t make it through the 3 hour glucose test without throwing up. My doctor wrote me a new prescription for a 2 hour test and I’m not sure how this is going be any different. 40 minutes into the test is as long as I made it with the 3 hours so if it’s the same exact test just an hour shorter, how will this help? Does anyone know if there is a difference between the two that I don’t know about? I can’t find anything on google and I didn’t get a chance to ask my doctor. 😩