Could Polyphenolic Food Intake Help in the Control of Type 2 Diabetes? A Narrative Review of the Last Evidence

Background: Diabetes is one of the largest global public health concerns, imposing a heavy global burden on public health as well as socio-economic development, and about 90% of adults with this condition have type 2 diabetes (T2D). Introduction: Beyond the hereditary factor, there are several risk factors connected to the development of this syndrome; the lifestyles play, increasingly, a predominant role in the development of the metabolic complications related to T2D and a significant role in the onset of this syndrome is played from an unbalanced diet. Polyphenolic food is plant-based food including vegetables, fruits, whole grains, tea, coffee, and nuts. In recent years, there is growing evidence that plant-foods polyphenols, due to their biological properties, may be nutraceuticals and supplementary treatments for various aspects of T2D. Polyphenols may influence glycemia and T2D through hypoglycemic properties as reduction of insulin resistance, reduced fasting blood glucose, and glycosylated hemoglobin value. Based on several in vitro, animal models and some human studies, is has been detected that polyphenol-rich products modulate carbohydrate and lipid metabolism, attenuate hyperglycemia, dyslipidemia, and insulin resistance, improve adipose tissue metabolism, and alleviate oxidative stress and stress-sensitive signaling pathways and inflammatory processes. Methods: This manuscript summarizes human clinical trials issued within the last 5 years linking dietary polyphenols to T2D, with a focus on polyphenolic-foods typical of the Mediterranean diet. Results: Polyphenolic food can also prevent the development of long-term diabetes complications including cardiovascular disease, neuropathy, nephropathy, and retinopathy. Conclusion: Further investigations as other human clinical studies are needed to obtain the best dose and duration of supplementation with polyphenolic food in T2D patients.