Don’t have experience with bitter melon, but have experienced the BG-lowering effect of goji berries, which ARE actually quite palatable. The problem with such “treatments,” however, is the inconsistency in strength of effects and unpredictability of their duration. While I was curious enough to experiment once, adding such items to my diet is not something I am interested in, especially because of the interaction with insulin.
I think in general it’s a bad idea for anyone using insulin and even T2s who might not be should probably consult with an endo or CDE before they try such foods.