Tannins and vascular complications of Diabetes: An update

Diabetes mellitus is a chronic metabolic disorder associated with persistent increased level of glucose in the blood. According to a report by World Health Organisation (WHO), prevalence of diabetes among adults over 18 years of age had reached to 8.5% in year 2014 which was 4.7% in 1980s. The Prolong increased level of glucose in blood leads to development of microvascular (blindness, nephropathy and neuropathy) and macrovascular (cardiovascular and stroke) degenerative complications because of uncontrolled level of glucose in blood. This also leads to the progression of oxidative stress and affecting metabolic, genetic and haemodynamic system by activation of polyol pathway, protein kinase C pathway, hexosamine pathway and increases advanced glycation end products (AGEs) formation. Diabetes mellitus and its associated complications are one of the major leading causes of mortality worldwide. Various natural products like alkaloids, glycosides, flavonoids, terpenoids and polyphenols are reported for their activity in management of diabetes and its associated diabetic complications. Tannins are systematically studied by many researchers in past few decades for their effect in diabetes and its complications. The present review was designed to compile the data of tannins and their beneficial effects in the management of diabetic complications. Literature search was performed using various dataset like pubmed, EBSCO, proQuest Scopus and selected websites including the National Institutes of Health (NIH) and the World Health Organization (WHO). Globally, more than 400 natural products have been investigated in diabetes and its complications. Tannins are the polyphenolic compounds present in many medicinal plants and various dietary sources like fruits, nuts, grains, spices and beverages. Various reports have shown that compounds like gallic acid, ellagic acid, catechin, epicatechin and procynidins from medicinal plants play major role in controlling progression of diabetes and its related complications by acting on molecular pathways and key targets involved in progression. Many chemists used above mentioned phyto-constituents as a pharmacophore for the developing new chemical entities having higher therapeutic benefits in management of diabetic complications. This review focuses on the role of various tannins in prevention and management of diabetic complications like diabetic nephropathy, diabetic neuropathy, diabetic retinopathy and diabetic cardiomyopathy. It will help researchers to find some leads for the development of new cost effective therapy using dietary source for the management of diabetic complications.