The association of dietary glycemic index with the prevention and treatment of COVID-19: a narrative review

In 2019, a new coronavirus causing a flu-like syndrome was discovered in Chinese province of Hubei and there was a subsequent outbreak in Wuhan in December 2019. The severity and mortality of COVID-19 are affected by several preexisting comorbidities such as type 2 diabetes mellitus (T2DM). A more severe complication of COVID-19 in patients with diabetes could be due to the fact that hyperglycemia and insulin resistance, as important features of diabetes mellitus, are associated with a higher expression rate of angiotensin-converting enzyme-2 (ACE-2). ACE-2 can act as the entry site for SARS-CoV-2 to lung cells. Furthermore, in diabetes mellitus, increased inflammatory responses and impaired immune function are often present. Glycemic index (GI) and glycemic load (GL) are the characteristics of the diet that can affect glycemic control and insulin resistance. These two characteristics could possibly affect infections through their effect on gut microbiota composition, free radical synthesis, and mitochondrial loading. Therefore, it can be proposed that dietary GI and GL might be important factors in the development of COVID-19.