Table 1.

Commonly used herbs to treat diabetes

Name	Active constituents	Beneficial effects/hypothesized mechanism of action	Side effects/drug interactions and contradictions	References
Bitter melon (Momordica charantia)	Momordin, charantin, polypeptide P, vicine	Hypoglycemic action, insulin mimetic, enhances glucose uptake by tissues, inhibition of glucose producing enzymes, enhances glucose oxidation (G6PDH pathway)	Gastrointestinal discomfort, hypoglycemic coma, favism, hemolytic anemia in persons with G-6PDH deficiency, abortifacient activity of α and β momorcharin, hypoglycemia when used with sulfonylureas	[28, 117]
Fenugreek (Trigonella foenum- graecum)	Saponins, glycosides Seeds contain: alkaloids, 4-hydroxyisoleucine, fenugreekine	Insulin secretagog, hypoglycemic activity, lipid-lowering effects, increase HDL cholesterol, Slows carbohydrate absorption and delays gastric emptying, inhibits glucose transport, increases insulin receptors, improves utilization of peripheral glucose	Diarrhea, gas, uterine contractions, allergic reactions, drug interaction with hypoglycemic agents, anticoagulant drugs, MAO inhibitors, contraindicated in pregnancy	[27, 117]
Panex ginseng, P. quiquefolius (Ginseng)	Ginsenosides	Insulin mimetic, hypoglycemic action, enhances psycho-physiological performance, stimulates immune system, may decrease carbohydrate absorption in portal circulation, may increase glucose transport and uptake, may modulate insulin secretion, alters hepatic glucose metabolism	Estrogenic effect with breast tenderness, amenorrhea, vaginal bleeding and impotence, hypertension, insomnia, interacts with anticoagulant and antiplatelet medications; hypoglycemic agents; corticosteroids; oral contraceptives; digoxin; MAO inhibitors and tricyclic antidepressants; diuretics	[27, 28, 118]
Ginkgo (Ginkgo biloba)	Flavonoids (ginkgo-flavone glycosides), terpenoids (ginkgolides and bilobalides)	Inhibit the platelet-activating factor, useful in cerebrovascular insufficiency and peripheral vascular disease, antioxidant, neuroprotective	Transient headaches, cross allergenicity with poison ivy, interacts with anticoagulants, SSRI, MAO inhibitors	[27, 52, 119]
Aloe vera	Glucomannan	Fiber may promote glucose uptake, pharmacokinetic interaction (CYP3A4), pharmacodynamic interaction (enhancement in adipose tissue insulin signaling pathway)	Abdominal pain, laxative component induces diarrhea, additive hypoglycemia if combined with secretagogs, drug interactions with sevoflurane, pioglitazone, repaglinide	[28, 52, 117, 120]
Cinnamomum zeylanicum	Compound similar to procyanidin type-A polymers, coumarins	Increases insulin sensitivity by increasing PPAR (alpha and gamma) expression, increases cellular glucose entry by enhanced insulin receptor phosphorylation and translocation of GLUT4 glucose transporter to the plasma membrane, promotes glycogen synthesis	Skin irritations if used topically, interacts with secretagogs and cause hypoglycemia, coumarins possess anticoagulant, carcinogenic, and hepatotoxic properties	[117, 121]
Gymnema sylvestre	Gymnemosides, saponins, stigmasterol, and amino acid derivatives (e.g., betaine, choline, and trimethylamine)	Insulin secretagog, increases glucose uptake promoting enzymes, stimulates and increase beta cell number	May cause hypoglycemia when combined with secretagogs	[28, 117]
Opuntia streptacantha (Nopal)	Mucopolysaccharide Fibers, pectin	Slow carbohydrate and lipid absorption, possibly increases insulin sensitivity	Diarrhea, nausea, abdominal fullness, increases stool volume, drug interaction—improved blood glucose and insulin with sulfonylureas (without hypoglycemia)	[52, 117]
Coccinia indica (ivy gourd)	Pectin, triterpenes	Insulin mimetic, hypoglycemic activity, helps lower elevated levels of glucose-6-phosphatase and lactase dehydrogenase	Allergenic plant components may cause hypoglycemia when combined with secretagogs	[52, 121]