I was recently switched from januvia (sitagliptin) to lantis insulin and almost immediately developed extremely hig blood pressure attacks as high as 257. normal?

Don't blame insulin: Something else is going on. Lantus (insulin glargine) does not cause hypertension by itself. If you were under poor control, and now your glu values are better, you may be retaining fluid, and that can raise blood pressure. Do you have kidney disease? You and your doctor, perhaps with the help of a specialist, need to figure this out.

Blood pressure?: Do you mean blood pressure of 257 or blood sugar of 257? Lantus (insulin glargine) should not cause elevation in blood pressure unless you took it right after the injection which in that case is due to anticipation of the shot (but that's still very high- check your BP cuff). If blood sugar, i wouldn't focus on one number but rather the trend through the day with lantus (insulin glargine).