Keep in mind there's a big difference between type 1 and 2 diabetes. I notice a lot of people are talking about them interchangably, but they're really not very similar. I have type 1, formerly called juvenile diabetes.
When I was diagnosed they did a blood test, no fasting, no orange drink, and had the results in about an hour. Then I was sent off to spend a week in children's hospital. Don't now how it works to be tested for type 2.