The Relationship of Fruits and Fruit-Products Consumption with Glucose Homeostasis and Diabetes: A Comprehensive Update on the Current Clinical Literature

Type 2 diabetes mellitus is a major contributor to morbidity and mortality worldwide. This disease often leads to poor health outcomes, such as neuropathy and diabetic foot ulcers, and increased risk for comorbidities such as cardiovascular complications and renal disease. Lifestyle modifications including diet and physical activity interventions are often explored as prevention and management strategies for T2DM. It is well established that fruits are a rich source of fiber and a variety of phytochemicals, vitamins, minerals, and bioactive compounds that can help optimize human health. Unfortunately, many experts associate the consumption of fruit with a moderate to high glycemic index (GI), which leads to a spike in blood glucose and eventually elevated hemoglobin A1c (HbA1c). The purpose of this comprehensive review is to outline the current clinical literature on the relationship between fruit consumption and various indices of glucose metabolism. A variety of fruits have been clinically studied to determine this relationship, namely in the fresh form (e.g., berries, apples, watermelon, cherries, mangoes), dried fruits (raisins and dates), and juices (derived from cranberry, orange, grape, cherry, and pomegranate). Overall, intake of fruits and fruit-derived products is beneficial for healthy subjects and subjects with T2DM regarding their impact on glucose metabolism and other cardiometabolic markers (e.g., inflammatory responses, lipid profiles). Nonetheless, it is more advisable for diabetic patients to consume fresh or dried fruits rather than fruit-derived products. A special consideration needs to be attributed to both the amount of fruit intake with regards to their respective GI and glycemic load (GL), and when these fruits are consumed. Trials with more a comprehensive design and specific outcomes are required to reveal the mechanisms underlying the beneficial effects of fruit consumption on the T2DM population particularly.