Medicinal Plants for the Treatment of Type 2 Diabetes

Introduction

Diabetes mellitus, a chronic state of metabolic diseases, is caused by deficiency of insulin secretion and insulin activity. There are three principal types of the disease: type 1, type 2 and gestational, among them, type 2 diabetes or non-insulin dependent diabetes is the most prevalent form in the population of the world (Jin et al., 2019). The prevalence of this pathology has significantly increased from 285 million (9.3%) in 2019 to 578 million (10.2%) in 2030 and 700 million (10.9%) in 2045 (Federation, 2019). Although the main risk factors for T2D are obesity, age, family history, hypercaloric diets and inactive lifestyle, the influence of this disease on non-obese and physically active people is important in further researches concentrated on the onset mechanism (Ferhati et al., 2019). The stable levels of glucose are maintained by a complicated mechanism containing hepatic glycogenlysis and gluconeogenesis. After a meal, pancreatic β-cells secrete insulin preventing hepatic glucose output and stimulating the glucose absorption into peripheral tissues (Alvim et al., 2015). The World Health Organization has suggested that the oral glucose tolerance test (OGTT) is designed for the diagnostic criteria of diabetes with fasting glucose 7.0 mmol/L or more. In addition, the expert committee of the American Diabetes Association recommended a cut-point for the diagnostic criteria at 6.5% or more of HbA1c level (Forouhi & Wareham, 2010). The aim of therapeutic options is to maintain blood glucose levels of patients close to physiological range and to prevent serious symptoms as well as late complications in long term. Antidiabetic therapy currently contains oral drugs reducing hyperglycaemia and exogenous insulin injection as a last method (Ferhati et al., 2019). This review article will focus on the mechanism of T2D with some potential therapeutic targets. We also summarize natural products as antidiabetic agents and their mechanisms of action for the treatment of T2D.