This chapter focuses on diet, nutrition, and human health, as well as the dietary patterns of blue zones, areas with exceptional longevity. It will also highlight the glycemic index (GI), diabetes, and antidiabetic plants. Superfoods are nutrient-dense foods that offer excellent benefits for humans. Diet, nutrition, and lifestyle are crucial determinants of human health and longevity. Research on dietary patterns of blue zones—regions known for exceptional longevity, such as Okinawa, Japan, and Sardinia, Italy—reveals the benefits of plant-based diets rich in whole grains, legumes, and vegetables. These regions emphasize whole, unprocessed foods that are nutrient-dense, promoting overall well-being and reducing the risk of chronic diseases. The glycemic index (GI), a measure of how quickly foods raise blood sugar levels, plays a significant role in managing and preventing diabetes. Low-GI foods, including whole grains and fiber-rich fruits, help maintain stable blood glucose levels and reduce the risk of diabetes. Antidiabetic plants, such as bitter melon and cinnamon, have demonstrated potential in modulating blood sugar and improving insulin sensitivity. Superfoods, such as blueberries, kale, and chia seeds, are nutrient-dense foods that offer numerous health benefits, including antioxidant properties, heart health support, and anti-inflammatory effects. Plant-based diets, which emphasize whole, minimally processed foods, provide essential nutrients, including vitamins, minerals, and fiber, which support optimal health. Adopting plant-based dietary patterns and prioritizing whole grains and fiber can enhance human health, improve longevity, and potentially help to reduce metabolic disease risks.