Type 2 diabetes has already been proved preventable by curcumin.
https://www.ncbi.nlm.nih.gov/pubmed/22773702
http://care.diabetesjournals.org/content/diacare/35/11/2121.full.pdf
A study 3 years earlier had investigated how curcumin exercised its anti-diabetic effects:
https://www.ncbi.nlm.nih.gov/pubmed/19665995
So why so we need another drug? Purely for drug company profits.
Because there is no cure for type 1 yet