Sugar Level refers to the level of sweets consumed by a playable character used to perform that character's Sugar Rush Attack. This requires a 100% Sugar Level or above to perform. The Sugar Level will also continue to decrease, while the character's Magic Circle continues growing.
If the character is hit by a bullet during Sugar Rush mode, he will be forced out of Sugar Rush mode, and the Sugar Level will be reset to 0. The character will not lose a Life, but due to the loss of sugar, everything around him will move much faster until his Sugar Level is back to 100.
It is also used to power up that character's base attack. For every added 100%, ranging up to 300, the base attack will become more widespread and powerful.