Antioxidants fight oxidative stress. And oxidative stress is thought to increase the risk for type 2 diabetes. You might think that the more antioxidants you take, the less your risk for diabetes. This study found that more is not necessarily better, and may in fact raise the risk for diabetes:Reactive Oxygen Species Enhance Insulin Sensitivity, Cell Metabolism, October 2009
Mice that were fed a high-fat diet, but that lacked an enzyme that acts like an antioxidant (glutathione peroxidase), were less likely to develop insulin resistance - a precursor to diabetes - than normal mice who had this enzyme. When the enzyme-deficient mice were given an antioxidant (N-acetylcysteine), they became more insulin resistant.
Oxidized compounds may be beneficial by acting as signals - inhibiting the action of enzymes that can slow the action of insulin.
This study found that, at least in mice, antioxidants promote insulin resistance.
