Are you on insulin? IF you are, then you should give a correction dose of insulin, based on the instructions of your dr.
If you are not on insulin / if the blood sugar does not start to come down after correction dose of insulin, you should go to the emergency room.
Blood sugar this high puts you at serious risk of diabetic ketoacidosis (life-threatening) or even stroke (blood with this much sugar in it will become thicker than it should be - like syrup. Do not eat any carbs when blood sugar is this high. Drink plenty of water, but even more importantly go to the nearest emergency room.
Bottom line. Get assistance and go to emergency room.
Your doctor should advise you about this as it depends on on your situation however drinking lots of water can help.