The available information on turmeric is widespread, and compelling. It is a traditional treatment specifically for diabetes, and many sources cite studies that have shown positive results for lowering blood sugar.

I found references frequently to Ayurvedic medicine, which may or may not recommend itself to you as a valid point in its favor. It is said to act on blood sugar levels both in increasing metabolism and stimulating insulin. It is high in chromium, which may count for part of that affect.

Turmeric is a common spice, and is used in cooking, sometimes as a cheap alternative to saffron, and sometimes in pickles and other common uses. It is yellow, and looks a lot like ground mustard.

Information on safety of this herb is also lacking, possibly because safety is assumed because of its widespread use as a spice. But there is a huge difference between using something in the minute quantities of a seasoning, and using it in larger doses as a medicinal supplement.

Proceed with caution if this is something you want to try, and do a little more research on its use and safety.