I am sure you don't like these numbers, but I went through your recent posting history and saw that Carolyn suggested a switch to Levemir or a Lantus dose reduction here. Seems like the Lantus dose reduction is your strategy right now.
However, because of such sustained, high BG levels, I will suggest that you get some ketostix and check Sam's urine for ketones, if you aren't already.
And although I have not used Lantus, Carolyn may have a good point regarding Lantus just not working well for some cats. I can whole-heartedly endorse Levemir as the very viable alternative!