Medicinal Plants and Bioactive Compounds in the Management of Type 2 Diabetes Mellitus (Part I)

Abstract

Type 2 diabetes mellitus (T2DM) is a common metabolic disorder characterised by chronic hyperglycaemia, insulin resistance and progressive beta-cell dysfunction. It is often accompanied by dyslipidaemia, low-grade inflammation and an increased risk of cardiovascular disease. While pharmacological therapies are effective in controlling blood sugar levels, their long-term use may be limited due to variable efficacy, adverse effects and an inability to sufficiently prevent complications in certain patient groups. Consequently, there has been a growing focus on medicinal plants and dietary bioactive compounds as complementary strategies with multi-target metabolic actions. This review summarises the current evidence regarding the anti-hyperglycaemic potential of various medicinal plants, such as Cinnamomum spp., Panax spp., Zingiber officinale, Allium sativum, Allium cepa, Aloe vera, Sesamum indicum, Azadirachta indica, Momordica charantia, Ocimum tenuiflorum and Curcuma longa. The emphasis is on their phytochemical profiles, mechanisms of action, and findings from in vitro, in vivo, and clinical studies. The antidiabetic effects of these plants are mainly attributed to compounds such as polyphenols, flavonoids, saponins, and terpenoids, which modulate key metabolic pathways. Reported mechanisms include the inhibition of carbohydrate-digesting enzymes, the improvement of insulin secretion and sensitivity, the enhancement of glucose uptake (e.g. via the AMPK/GLUT4 pathways), and the reduction of oxidative stress and inflammation. Preclinical and clinical studies suggest that these plant-derived compounds may contribute to improved glycaemic control, including reductions in fasting glucose and HbA1c. However, clinical evidence remains inconsistent due to heterogeneity in study design, plant composition, dosage, and patient characteristics. Future research should prioritise the standardisation of formulations, rigorous clinical validation and the evaluation of long-term safety, in order to support the integration of these compounds into evidence-based diabetes management.