OK, I wondered if you were talking about "symogyi". The original study on that was done on a very small group of humans, years ago, when only harsh insulins were available. The article posted in
this link, includes research done at a university on cats and Lantus and debunks the myth of Symogyi, especially if the cat was started on a low dose of Lantus and increased systematically. Unfortunately, the myth is still all over the place. The only time we see a true issue is when a cat is started on way too high a dose. Not the case with Riley.
When I look at Riley's spreadsheet I see more high numbers after starting 3 units.
Remember, you aren't looking at the mid cycle nadir or the the nadir, cause you have hardly any tests then. We determine the dose based on how LOW it takes the cat, or the nadir points. You don't need to test throughout the night but so many cats go lower then that we strongly recommend getting a before bed test, to help fill in the picture. If he's getting enough insulin at 3 units to get him lower than he's been before (it could still be very safe numbers, just lower than he's used to), then he will bounce higher for a while until he gets used to it.
Going backwards in dose seldom works. I've been in your shoes.

Some cats just need higher doses of insulin to get their blood glucose numbers moving. 3 units is still relatively small.