Confused and worried about my cat

Please help me someone! 

I am very confused and worried about my cat. She had one blood test with Glucose levels at 399 and was diagnosed with diabetes. I did some research online and saw some information that disagrees with my vet.I have read on several sites that cats glucose levels when they are stressed out can cause high glucose readings. She is a very high anxiety cat and she has an infection which I also read could raise levels. The research I have done online suggests that with stress alone could raise to 400 in cats. I took her to another vet and she told me the same as the last vet. Am I going crazy? Why is all the information online state that levels could easily reach 400 when the cat is stressed, and the vet tells me something else. 

I guess I am looking for another persons opinion - should I start her on insulin due to her levels being at 399 when she is highly stressed and has an infection? Or should I continue her diabetic diet and hope that her levels were only high due to stress? Please help me!!

By the way she is doing much better now that she is on the new diet. She is more active, has lost weight, and is brighter.

Thank you any opinion would be greatly appreciated!

There is another blood test called a serum fructosamine test

This test is more accurate than a one time blood glucose test which can be dramatically affected by stress.  This test will tell if the blood glucose has been high over a period of time prior to the blood draw. The vet did it for one of my kitties that  had a high glucose level and it came back normal.

Denice,

I will call my vet and ask them about this test! 

Thank you so much for your advice!