Didn't you say you got a different insuline? It's possible your body ignores it. Call your doc asap, please!
There is a second possibility, though much less likely: the liver can turn sugar into fat without the help of insuline. This fat is stored for emergencies when it's turned back into sugar again by the liver. Maybe you are too hungry and your liver started to use up the fat reserves. Your doc can test that by having a look at your Triglyceride levels. Triglyceride is the transport variety for fat. At your age the level shold be about 200 [mg/dl]. Given your diabetes 300 would still be not too bad. Anything beyond 400 would be alarming even for a diebetic, unless your family has a history of too high Triglyceride levels (hereditary Hypertriglyceridemia).