We know that obesity can be a cause of diabetes, but can diabetes actually cause obesity?

Depends: If you stay on a fixed dose of Insulin and try to eat more so you don't get low blood sugars, then yes, you can end up gaining some weight. Impt to distinguish the fact that this does not mean Insulin causes obesity (only if excessive Insulin results in overeating) patients on Insulin should have the dose adjusted to match healthy food intake, not the other way around.

Not directly: Diabetes per se does not directly cause weight gain but some drugs used to treat diabetes can cause weight gain.