It also activates lipogenesis, where very cool chemical reactions in the liver convert glucose to triglycerides and then ship them off to your adipose tissue for storage.
It increases these other phenomena like for instance the pentose phosphate shunt and the Randall cycle and the de novo lipogenesis which is what cancer cells need to be able to multiply and divide.
At this point, there's nowhere to put incoming carbohydrate, so insulin has to turn it into fat via a process called de novo lipogenesis so it can be stored in the only place available: your fat cells.