Dietary zinc does not appear to prevent diabetes

Reported by Susan Aldridge, PhD, medical journalist

There is no hard evidence that zinc can prevent diabetes, according to a new study.
There is laboratory evidence that zinc can help promote the production and action of insulin. So you might think that it can also help to prevent diabetes. The Cochrane Collaboration, an international organization that evaluates medical treatment, has looked at the available evidence on zinc, insulin and diabetes and has found no proof that zinc will help you avoid diabetes.

They found 192 clinical studies involving zinc, insulin and type 2 diabetes. But only one of these met the strict criteria for a Cochrane review. In this one study, 56 obese women who did not have diabetes received either 30 milligrams oral zinc supplementation or placebo daily for four weeks. There were no significant differences in measures such as insulin resistance or blood glucose after this time. This is at odds with lab studies that show that zinc binds to insulin and improves its solubility, which could make it more available. This lack of clinical evidence does not mean zinc cannot play a role in preventing diabetes - only that more research, and larger trials, are needed to settle the question one way or the other.

Source
Cochrane Database of Systematic Reviews 2007 Issue 1