According to the Express paper
"The CuraLin supplement contains 10 Ayurvedic herbs: swertia chirata, turmeric, fenugreek, gymnema sylvestre, bitter melon, picrorhiza kurroa, syzygium cumini, tinospora cordifolia, melia azadirachta and amla."
Note: this list is commonly also found in many Indian curries and the supplement originated in India, which happens to have one of the highest concentrations of T2D.
I have also seen a report that it also contains St John's Wort which has a warning against it for triggering mental issues such as depression.
As has been pointed out by others, if this was actually producing significant effects, then Big Pharma would be synthesizing it to mass produce a pill for all. After all, there is no copyright on a shopping list, but in a synthesized product = ££££'s None of the ingredients listed has made it into an OTC pill. I doubt even Herbalife or Vitalife would touch it. Seems to be MLM operators only hence the inflated price.
PS I have used some of these as supplements myself, and with a small amount of success, but now I use diet instead. Its cheaper that way.