Abstract / Summary
Diabetes mellitus is a major metabolic disorder characterized by persistent elevation of blood glucose and progressive disturbances in carbohydrate, lipid and protein metabolism. Type 2 diabetes mellitus (T2DM), the most common form of diabetes, develops through a complex interaction of insulin resistance, pancreatic β-cell dysfunction, oxidative stress, inflammation and abnormalities in cellular glucose metabolism. Although several effective pharmacological treatments are available, the increasing prevalence of diabetes and the need for additional therapeutic approaches have stimulated interest in medicinal plants and plant-derived bioactive compounds. During the last decade, considerable research has examined herbal medicines such as Curcuma longa, berberine-containing plants, Trigonella foenum-graecum, Nigella sativa, Momordica charantia, Zingiber officinale and Gynostemma pentaphyllum. These agents contain chemically diverse constituents, including polyphenols, alkaloids, flavonoids, saponins and terpenoids. Experimental studies indicate that these compounds may influence glucose metabolism through multiple mechanisms, including enhancement of insulin signaling, activation of AMP-activated protein kinase, modulation of PI3K/Akt signaling, improvement of GLUT4-mediated glucose uptake, inhibition of carbohydrate-digesting enzymes, reduction of oxidative stress and suppression of inflammatory pathways. Human studies and recent meta-analyses have reported potentially beneficial effects on fasting blood glucose and glycated hemoglobin for several herbal preparations, although the results are not uniform. Major limitations include differences in plant material, extraction procedures, doses, formulations, bioavailability and clinical study quality. Therefore, further standardized preclinical and clinical research is required before these preparations can be considered established therapeutic alternatives. This review discusses the recent evidence concerning emerging herbal medicines for diabetes, their proposed mechanisms, clinical findings, safety considerations and future research priorities.