I am so sorry about her weak legs today. I don't have any experience with neuropathy or arthritis so I hope that others can weigh in about her being good one day and really bad the next.
I wouldn't say this is bouncing today. Looks like she has some New Dose Wonkiness today . Below is taken from the stickie, "New to the Group " :
Also worth noting:
"Many cats will occasionally react to an increased dose with increased BGs - within the first 2 to 3 days after an increase, usually lasting for less than 24 hours. Nobody really knows what the reason for this phenomenon is (perhaps a "panicky liver"?) - hold the dose and ignore the fluctuations." http://www.tillydiabetes.net/en_6_protocol2.htm. Here in the Lantus, Basaglar, and Levemir Insulin Support Group (ISG), we've affectionately dubbed this unexplained phenomenon
"New Dose Wonkiness" (NDW).
If she stays flat yellow like this, it sometimes indicate a drop in BG's in the next cycle or two.