Bisphenol-A, monomer of the polycarbonate and other types of plastics (that are used to make plastic bottles for example), and that could be hydrolyzed and released from the polymer easily, is an endocrine disruptor and acts like estrogen and could keep our body in a pregnant-like state. Pregnant like state is characterized by high insulin resistance in peripheral tissue as the nutrients should be directed to the embryo in pregnant women instead of being stored in peripheral tissue. Insulin resistance leads to hyperinsulinemia (increased insulin production from the beta cells of the pancreas) and subsequently this could lead to diabetes. So constant exposure to this chemical can lead to a constant pregnant like state and potentially diabetes.
Funny enough the expansion of diabetes in humans and the use of plastic bottles coincide.
This may not be the sole cause of diabetes, but think twice before you drink from a plastic bottle or eat lunch from a plastic box.
Link to the article: http://www.nature.com/nrendo/journal/v7/n6/full/nrendo.2011.56.html