Thank you guys for the warm welcome. I really feel guilty in a sense... in telling you all this, but I realized after a few days that she needed to be put to sleep.
I was prepared to give shots morning and night. That wasn't the big deal, and was no more complicated than say, giving pills. I would have sacrificed a lot for my kitty. I loved her very much. I am single and I have a full time retail job that doesn't pay a lot. I knew it was going to be challenging but the more I researched the more I realized it was more than just challenging.
As the only person who would be doing the treatment if I did treat her, if anything happened to me (car accident, a bad case of the flu, hospitalization for any reason), etc. she would suddenly go without medicine. Also with the syringes, the test strips, the sharps containers, the lancets, the extra vet visits, the wet food, etc. and after being financially wiped out by another pet having to have a surgery recently, I realized I couldn't afford all that, at least not on a consistent basis.
Even if treated she would have been suffering because of the risk of overdosing medicines, and possible complications. She had a heart murmur already as well and had been diabetic for a long time apparently but I hadn't realized it. This had obviously done damage. I used to have another animal (a ferret) who went through many similar symptoms to what my cat would have been experiencing so I am not new to this game. My ferret had insulinoma and I remember having to rub corn syrup on her gums to bring her out of hypo, etc. and I didn't want Serena to go through that.
I called my cat Serena smiley face because she had an almost perfect smiley face on her belly. Her fur had a unique texture. She was soft and velvety and had a completely different texture to her littermates. She was a talker. she would hold 'conversations' with me. She would meow, I'd meow back, and so forth. She reminded me a little bit of Luna from Sailor Moon because she had a fairly prominent white locket on her throat that reminded me of the yellow moon on Luna's forehead. Anyway... I will miss her. She was a really good kitty.