Second generation oral hypoglycemic agents, such as glyburide and glipizide, are often the treatment of choice in non-insulin dependent diabetes mellitus. These sulfonylureas are more potent osmotic agents than their predecessors and may give rise to crystalline lens changes and refractive error shifts in the absence of blood glucose variation. Such a case is presented, as is a detailed description of the mechanism of action of commonly prescribed oral hypoglycemic agents.