Hydrogel polymers for use, for example, in contact lenses, drug delivery systems and/or stimulating devices. In some embodiments, the hydrogel formulations comprise diluent(s) to improve the dehydration characteristics and mechanical properties of a hydrogel polymer formulation compared to those without diluent(s). The diluent(s) include, for example, water and hydrophilic diluent(s) such as humectants.