If your thyroid fuction has been the cause of feeling like this in the past, it may be the cause again. I knew I needed a test some years back, but the results came back as ok. However, I still felt tired and felt I was having to drag myself around. They wouldn't agree to re-test for three months, at which point I was back in the surgery asking for a test again. This time my levels were in my boots according to my GP. That really was the only problem.
In my opinion, the nurse is a loonie.
Edited to add: Unless you have been having repeated hypos ? Can you tell when your glucose level drops below 4 mml ?