Gestational diabetes goes away after birth po most of the time. It's affected by your carbohydrates intake (not necessarily sugar) so kung makakausap nyo po si OB asap, ask for recommendations anong ok na kainin and anong dapat iwasan.
Pregnancy is a very emotional time for many women, especially dahil sa hormones natin. Kasama na po dyan minsan yung napapaisip tayo ng kung anu ano. I'm a worrier too just like you, and for me, nakakatulong na nakakausap ko ang partner ko about it, and pag naririnig ko na nang malakas yung mga iniisip ko, ako na mismo nagsasabi na pinapangunahan ako ng takot kahit ok naman talaga ako.
So talk to you ob po about a diet plan to manage your condition, let them know about those things you worry about para maiexplain nila kung may dapat ka ba talagang ikabahala o wala. Good luck po.