I use Hello brand (watermelon flavor… lol) which is sweetened with erythritol and stevia. I actually only bought it because I don’t like mint flavored toothpaste, and it was one of the non-mint options (I’m pretty sure it’s intended for children though).
I really don’t know want to know what normal toothpaste has in it. If it has a sweetener that triggers insulin that may be the issue.
You could always go for Hello brand as mentioned, Lush also has toothy tabs which should work, or you can make your own with baking soda and some flavor oil (mint, clove, anything really).