They have blood testing
kits at the local
pharmacy. That is one way to check. Also if your blood sugar is high enough to spill over into urine you can use clinistix to void on and it will tell you if there is sugar in your urine,,,,,,,,and it should not be there.
There are symptoms such as thirst and itching. Go to AmericanDiabeticAsociation.com and they have the list of symptoms and a test you can take. If you have many symptoms then you should continue pursuing answers.