While there is laboratory evidence that zinc helps promote the production and action of insulin (preventing onset of type 2 diabetes), there is not enough clinical data available to support such a claim.

Eligible clinical data may still be lacking, but this doesn't necessarily mean that zinc doesn't have a role in diabetes prevention.

According to authors of a new systematic review of clinical studies (led by Vania Beletate of the Federal University of Sao Paola in Brazil) appearing in the current issue of The Cochrane Library:

The zinc-insulin link is supported by test-tube research: Laboratory studies show that "insulin may form a complex with zinc improving the solubility of this hormone in the pancreatic beta cells.

Insulin is needed to process glucose in the body. When insulin production or action is impaired, type 2 diabetes can follow. Zinc has a role in how the body produces and uses insulin, and because the body does not produce zinc on its own, "it must be obtained from outside sources."

The said review was left with a single trial (56 people with either zinc or placebo for four weeks), observing no effect, is too small and too short to be really conclusive about the effectiveness of zinc against diabetes.

Read the full report at CFAH.