Nutritional management of diabetes mellitus during the pandemic of COVID-19: a comprehensive narrative review

Objectives According to the recent epidemiological studies, patients with diabetes mellitus (DM) may be at higher risk of hospitalization due to COVID-19. Regarding the important role of nutrition on the immunity, the present review article aimed to outline nutritional support of DM during the outbreak of COVID-19 with a mechanistic insight. Methods Searches were performed in PubMed/MEDLINE, ScienceDirect, Scopus, and Google Scholar databases from 2000 until December 2020 using the following keywords. All relevant clinical and experimental studies published in English were included. Results Evidences revealed that hyperglycemia is a significant predictor of some viral infections including COVID-19 which can exacerbate the complications of DM. According to the literature review, adequate intake of dietary protein, fiber, essential fatty acids and some micronutrients especially vitamins D, C, B12, folate, zinc and selenium has beneficial effects on the prevention and treatment of COVID-19 in diabetic patients through modulation of innate and adaptive immune responses or direct effects on virus enzymes or the rate of cell entrance. Conclusions It is well understood that malnutrition may increase susceptibility to viral infections and disease progression. Therefore, considering nutritional status of diabetic patients and reasonable supplementation of the above mentioned nutrients can ameliorate the symptoms of COVID-19 in DM. However, further well-designed clinical trials are needed to determine their therapeutic dose.