NOTE: Until kitty is pretty well regulated, the description below is NOT indicative of a "typical" Lantus cycle. It takes time and patience for kitty to achieve this kind of cycle! The example below is what you're working towards. A relatively flat cycle is the ultimate goal.
Example of an ACTIVE Lantus cycle for most, but not all Lantus kitties:
+0 - PreShot number.
+1 - Usually higher than PreShot number because of the last shot wearing off. May see a food spike in this number.
+2 - Often similar to the PreShot number.
+3 - Lower than the PreShot number, onset has started.
+4 - Lower.
+5 - Lower.
+6 - Nadir/Peak (the lowest number of cycle).
+7 - Surf (hang around the nadir number).
+8 - Slight rise.
+9 - Slight rise.
+10 - Rising.
+11 - Rising (one of the quirks of Lantus/Levemir: some cat's blood glucose numbers dip around +10 or +11... not to be confused with nadir).
+12 - PreShot number.
An active Levemir cycle will have an onset at approximately +4 and a nadir around +8 - +10. However, please keep in mind every cat is different (ECID). Data collection will offer you a better picture of YOUR cat's response to either of these insulins.
Video: Levemir: Mode of Action
Initially, don't expect to see "active" cycles after every single shot whether you're using Lantus or Levemir. Chances are, your kitty had diabetes for some time before diagnosis. It requires time for kitty's body to become used to dropping into lower numbers than their bodies have become accustomed. Don't expect immediate results! Regulation takes time and patience: "Fluctuations are very common in this phase before BGs start to stabilize under consistent dosing: a typical curve of cat over the first 1.5 months on Lantus can be seen here: Lantus Starting Graph".
http://www.tillydiabetes.net/en_6_protocol2.htm