How does one get themselves tested for diabetes?

Diabetes runs in my family, and I've been advised by my elders that I should look into checking if I am prediabetic so I can start managing the family illness before it becomes an actual problem.

How does one go about doing? I've tried to schedule tests for myself before and was told by the phyician that I need a PCP's approval first. Do I just make a normal appointment with a PCP even though I am not sick, and just ask if they can get me tested randomly?