Most treadmill stress tests use a standard method referred to as the "Bruce Protocol". The test is a combination of speed and incline. The treadmill used has this program built into it, so your test would be just like my test. The idea is to walk as long as you can. Your test will start very slowly, but will increase in speed and incline at regular intervals, The test itself is designed so most people eventually "fail". That is, most everybody eventually has to stop from exhaustion. I've gotten to 13 minutes before I had to hit the big red button to stop the treadmill. At that point, the speed of the treadmill requires the individual to run, and the incline is fairly steep. The object is to go as long as you can so your heart can be seen in a stressed situation. Your duration will be completely difference from another's. Prior to the test, you will be wired up in a standard EKG configuration. The wires will most likely be connected to a box on your waist, and the telemetry will be sent wirelessly to the EKG machine. Your test can be administered by a technician, or a physician. I go to a little country hospital where my cardiologist actually administers the test.
There is another type of stress test referred to as a chemical stress test where the patient is given drugs that simulates the heart under stress. I think they'd prefer to have you walk if possible.
I don't believe they will treat you any differently being diabetic. You will be closely monitored during the test and someone is always physically close to you to assist. Don't sweat this. It's easy!
There is no need for you being afraid. You will be monitored closely during the test. Any sign of something not ok will make the doctor stop the test.
There is really need reason to think you will pass out during the testing.
When you stop the exercise a drop in blood pressure can make you feel a little dizzy, that's all.
Oh yes, it is tiring :-)