I only learned about carb counting a year ago (after 15 years in big D club)- my revelatory moment was realising that I had to do insulin for fruit juice! My brains were still working on the info I’d been given as an 11 year old, which was that a mars bar treated a hypo just fine, and that I should never ever fiddle with my insulin (the good old 2 injection a day years eh?)! Best piece of advice- read the nutrition labels on packaging! (and the salter scales are good too)