OBJECTIVETo assess the clinical efficacy of nutritional amounts of grape polyphenols (PPs) in counteracting the metabolic alterations of high-fructose diet, including oxidative stress and insulin resistance (IR), in healthy volunteers with high metabolic risk.RESEARCH DESIGN AND METHODSThirty-eight healthy overweight/obese first-degree relatives of type 2 diabetic patients (18 men and 20 women) were randomized in a double-blind controlled trial between a grape PP (2 g/day) and a placebo (PCB) group. Subjects were investigated at baseline and after 8 and 9 weeks of supplementation, the last 6 days of which they all received 3 g/kg fat-free mass/day of fructose. The primary end point was the protective effect of grape PPs on fructose-induced IR.RESULTSIn the PCB group, fructose induced 1) a 20% decrease in hepatic insulin sensitivity index (P < 0.05) and an 11% decrease in glucose infusion rate (P < 0.05) as evaluated during a two-step hyperinsulinemic-euglycemic clamp, 2) an increase in systemic (urinary F2-isoprostanes) and muscle (thiobarbituric acid–reactive substances and protein carbonylation) oxidative stress (P < 0.05), and 3) a downregulation of mitochondrial genes and decreased mitochondrial respiration (P < 0.05). All the deleterious effects of fructose were fully blunted by grape PP supplementation. Antioxidative defenses, inflammatory markers, and main adipokines were affected neither by fructose nor by grape PPs.CONCLUSIONSA natural mixture of grape PPs at nutritional doses efficiently prevents fructose-induced oxidative stress and IR. The current interest in grape PP ingredients and products by the global food and nutrition industries could well make them a stepping-stone of preventive nutrition.

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Abstract The epidemic of coronavirus disease-2019 (COVID-19) is caused by the severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) virus. Some data describing characteristics and prognosis of patients with COVID-19 and diabetes are now available, for example for hospitalized patients in the CORONADO study. Potential links between diabetes and COVID-19 infection were already described. Indeed Angiotensin-converting-enzyme 2 (ACE2) has been identified as the receptor for the coronavirus spike protein, and ACE is expressed on pancreatic beta cells. It was suggested that SARS-CoV2 could induce beta cell damage and new onset diabetes, but the phenotype of these new cases of diabetes has not been described.This observation presented in that paper highlights the fact that COVID-19 infection may also trigger type 1 diabetes onset. Viral infection, in particular by enteroviruses but also by coronaviruses, is a well-known environmental trigger for the development of type 1 diabetes. In the case presented herein, there was a short delay between COVID-19 infection and diabetes onset. It remains to determine if the hyperinflammation/cytokine storm described with this infection could accelerate the onset of type 1 diabetes in genetically susceptible individuals.The relationship between SARS-CoV2 exposition and autoimmune diabetes development must be further studied, and incidence of type 1 diabetes will be carefully observed in the next months.

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