Cat with diabetes, sudden blindness, limp, vomiting?

Our family's cat was diagnosed with feline diabetes about two years ago, and nothing like this has ever happened before. She's 14 years old. Last night we gave her her regular food and insulin shot just as always. Now all of a sudden, this morning, she wouldn't get up off the floor. We tried picking her up and she bit my dad, which she never has done before. We set her down on the floor, and the front part of her body seems to be completely limp. We also think she might be blinded, or at least have blurry vision. Does she have high or low blood sugar?? Please help, I can't bare to watch my mom go through all this.