Polyherbal Strategies for Type 2 Diabetes: Clinical Evidence and Mechanistic Rationale for Bitter Melon, Black Cumin, Celery, Curry Leaves and Fenugreek

Type 2 diabetes mellitus is a complex metabolic disorder characterised by hyperglycaemia, insulin resistance, pancreatic β‐cell dysfunction, inflammation and oxidative stress. Multitarget botanical interventions may support glycaemic and metabolic management through diverse biological activities. This review evaluated clinical evidence for Nigella sativa , Trigonella foenum-graecum , Momordica charantia , Apium graveolens and Murraya koenigii in Type 2 diabetes and examined the mechanistic rationale for polyherbal approaches. Twenty clinical trials met the inclusion criteria. N. sativa improved fasting glucose and HbA1c, with seed oil showing more consistent effects on lipid and inflammatory parameters than seed powder. T. foenum-graecum reduced fasting glucose, HbA1c and atherogenic lipids, particularly at higher whole‐seed doses, whereas fibre‐free extracts mainly affected fasting and postprandial glycaemia and triglyceride concentrations. M. charantia produced modest improvements in glycaemic control with crude extracts and greater reductions in HbA1c and triglycerides with peptide‐enriched formulations. A. graveolens improved glycaemic, lipid and blood pressure parameters with seed extracts rich in 3‐ n ‐butylphthalide, whereas low‐dose whole‐plant powder mainly reduced body fat. M. koenigii improved glycaemic indices and measures of central adiposity in short‐term interventions. Study heterogeneity, small sample sizes, short intervention periods and variation in herbal preparations limited direct comparison across studies. Available evidence suggests complementary mechanisms among these botanicals, including improved insulin sensitivity, insulin‐mimetic activity, reduced carbohydrate absorption, antioxidant effects, anti‐inflammatory activity and lipid modulation. A polyherbal approach represents a plausible mechanistic strategy, although direct clinical evidence for synergistic effects remains unavailable. This review describes current clinical evidence for five botanicals with complementary antidiabetic activities and outlines priorities for future combination–based clinical research.