Diabetes is a chronic, metabolic disease characterized by elevated levels of blood glucose, which gradually causes serious damage to the heart, blood vessels, eyes, kidneys, and nerves. Over the past three decades, the prevalence of type 2 diabetes has increased dramatically in countries of all income levels. A series of cost-effective interventions can improve patient outcomes, regardless of the type of diabetes. Among these interventions, eating healthily has been identified as an effective approach for preventing type 2 diabetes and the complications and premature death associated with diabetes. With regard to dietary lipids, specific foods and dietary patterns rich in polyunsaturated fatty acids (PUFA) have been recommended to achieve optimal blood glucose levels. This review outlined and discussed current evidence and recommendations for the intake of PUFA, especially omega-3 and omega-6, for the prevention and/or treatment of diabetes.