Could also be bouncing I mentioned yesterday. From the Basics sticky:
Bouncing - is simply a reaction to what the cat's system perceives as a BG value that is "too low". "too low" is relative. If a cat is used to BG in the 200s, 300s or higher for a long time, then even a BG of 150 can trigger a "bounce". Bouncing can also be triggered if the BG drops too low and/or too fast. The pancreas, then the liver release glucogon, glycogen and counter-regulatory hormones. The end result is a dumping of "sugar" into the bloodstream. *Usually* bounces clear within 3days (6 cycles).