There are several blood tests doctors can use to help diagnosis of diabetes:
Random glucose test—given at any time during the day
Fasting glucose test—taken after you have gone without food for at least 8 hours
Oral glucose tolerance test—taken after fasting overnight and then again 2 hours after having a sugary drink
A1C blood test—shows your glucose level for the past 2–3 months
Your doctor may want you to be tested for diabetes twice before making a diagnosis.