With Blood sugar that high you should go to the hospital. That is very high and dangeras. As for lowering it the only thing you can do is use insulin and for that you need to go to a Hospital or ER.
To keep it from going higher stop eating ALL carbohydrates.. bread pasta soda if its a carbohydrate it will raise your BG.
You NEED to go to the ER if you are a Type 1 diabetic it can be deadly not to go. This stuff can kill you
I dont want to scare you... you need to go.!!!