I like Gator's idea of trying 0.9u. Yes, I recommended trying 0.8u, the drop on 1u (and definitely 1.5!!) looks a little steep to me, and HI to me is usually a red flag (when my cat was on WAY too little insulin I rarely got HIs, just #s in the 400 & 500s all day). I don't like to cry rebound, but I'm suspicious on this one. When the swings get wider - nadirs in the blue & PSs in the black - I think trying a lower dose for a couple days is warranted (not dramatically lower, just 0.9u, or try 0.8u and hold it for a couple days). It's counterintuitive, but the steep drops can trigger more rebound and compound the problem.