I take omeprazole about 30 minutes before breaking my fast, and for me it does not trigger an insulin response. TBH, I forget to take it quite often since beginning IF and find I don’t need it daily like I used to. Good luck!
Used to have GERD myself but haven’t had any symptoms whatsoever for 2-3 weeks now!
(Been doing 16:8 IF for 6 weeks)
Edit: not sure if it breaks your fast, but what time of day is your eating window?