Anti-Inflammatory Potential of the Anti-Diabetic Drug Metformin in the Prevention of Inflammatory Complications and Infectious Diseases Including COVID-19: A Narrative Review.

Metformin, a widely used first-line anti-diabetic therapy for the treatment of type-2 diabetes, has been shown to lower hyperglycemia levels in the blood by enhancing insulin actions. For several decades this drug has been used globally to successfully control hyperglycemia. Lactic acidosis has been shown to be a major adverse effect of metformin in some type-2 diabetic patients, but several studies suggest that it is a typically well-tolerated and safe drug in most patients. Further, recent studies also indicate its potential to reduce the symptoms associated with various inflammatory complications and infectious diseases including coronavirus disease 2019 (COVID-19). These studies suggest that besides diabetes, metformin could be used as an adjuvant drug to control inflammatory and infectious diseases. In this article, we discuss the current understanding of the role of the anti-diabetic drug metformin in the prevention of various inflammatory complications and infectious diseases in both diabetics and non-diabetics.

Role of Innate Immune and Inflammatory Responses in the Development of Secondary Diabetic Complications.

Increased hyperglycemia due to uncontrolled diabetes is the major cause of secondary diabetic complications such as retinopathy, neuropathy, nephropathy, and cardiovascular diseases. Although it is well known that increased oxidative stress, activation of the polyol pathway, protein kinase C and increased generation of advanced glycation end products could contribute to the development of diabetic complications, recent studies implicated the role of innate immunity and its related inflammatory responses in the pathophysiology of secondary diabetic complications. Increased activation of oxidative stress signaling could regulate NLRP3 inflammasome-mediated innate immune responses as well as NF-κB signalosome-mediated pro-inflammatory responses. This review article focused on the pathogenic role of innate immune and inflammatory responses in the progression of hyperglycemia-induced secondary diabetic complications. Specifically, we discussed in depth how deregulated innate immune and inflammatory responses could lead to an aggravated release of cytokines, chemokines, and growth factors resulting in the development of various secondary complications of diabetes.