I recently read that turmeric can improve diabetes type 1 and type 2 by being anti-inflammatory and increasing insulin sensitivity.
That sound almost too good to be true, so before I recommend that to my relative who suffers from type 2, I'd thought I'd ask around a bit, as I haven't found any first hand experience online, just articles.
Apparently you can also try curcumin (the isolated substance) which in combination with black pepper is supposedly more effective ... though there, too, I only found some people who wrote their inflammation issues with skin diseases have improved.