Diabetes mellitus is one of the most common endocrine diseases globally as the number of people with Diabetes Mellitus was around 422 million in 2014. 
Although there are many synthetic treatments, none of them is able to decrease the origin of the disease . The most common symptomatic treatments include regular injection of insulin or oral administration of antidiabetic drugs, such as sulfonylureas, α-glucosidase inhibitors, biguanides, thiazolidinediones, dipeptidyl peptidase-4 (DPP4) inhibitors, sodium-glucose co-transporter-2 (SGLT2) inhibitors, glinides, and parenteral administration of glucagon-like peptide-1 (GLP-1) agonists, which can cause moderate to severe side effects . For that, other alternative treatments are highly required for more efficient management. that is when Complementary and alternative medicine (CAM) comes to the ground . The World Health Organization has suggested the use of herbal drugs in the treatment of diabetes mellitus and its complications.
Many medicinal plants with antidiabetic and antihyperlipidemic effects are effective in the prophylaxis and treatment of DM.
Antidiabetic Plant Mechanisms
Most medicinal plants that used in diabetes Mellitus works by stimulating insulin secretion, augmenting peroxisome
proliferator-activated receptors (PPARs), inhibiting α-amylase or α-glucosidase, inhibiting the secretion of the
incretin, GLP-1, inhibiting advanced glycation end-product (AGE) formation, free radical scavenging plus antioxidant
activity, up-regulating or elevating translocation of glucose transporter type 4 (GLUT-4), and preventing development. 
Some Common Examples
Panax ginseng  and the diosgenin component in Fenugreek [7–9]: they have an insulin secretagogue action of the compound S-methyl cysteine sulfoxide which has been isolated from the onion plant (Allium cepa). 
bitter melon (Momordica charantia L.): it works by the activation of PPAR-α in rat tissues . as well as increasing the expression of human PPAR-δ mRNA and the production and activation of PPAR-δ is further upregulated through PPAR-δ promoter activity .
Azadirachta indica (Neem tree): it does have antihyperglycemic and anti-lipidemic actions in diabetic rats due to Azadirachtolide. It is also useful in the management of DM associated with an abnormal lipid profile .
Cinnamon bark species show inhibitory activity against intestinal α-glucosidase and pancreatic α-amylase  and even after chronic extract administration, α-glucosidase activity remains at a low level, so this natural product has promise in Diabetes Mellitus .
Rehmannia Glutinosa restrains AGE-mediated inflammation by inhibiting ROS production and NADPH-oxidase
activity and this is considered to prevent AGE-mediated problems in Diabetes Mellitus .
- World Health Organization. Global report on diabetes. ISBN 97892 4 156525 7 (NLM classification: WK 810). 2016.
- Li WL, Zheng HC, Bukuru J, et al. Natural medicines used in traditional Chinese medical system for therapy of diabetic mellitus. J Ethnopharmacol. 2004;92:1–21.
- Gourgari E, Wilhem EE, Hassanzadeh H, et al. A comprehensive review of the FDA-approved labels of diabetes drugs: Indications, safety, and emerging cardiovascular safety data. J Diabetes Comp.
- Gardner DG, Shoback D. Greenspan’s basic & clinical endocrinology. 9th ed. New York: McGraw-Hill Medical; 2013. p. 7–14.
- Nazarian-Samani, Z., Sewell, R.D., Lorigooini, Z. and Rafieian-Kopaei, M., 2018. Medicinal plants with multiple effects on diabetes mellitus and its complications: A systematic review. Current diabetes reports, 18(10), pp.1-13.
- Ota A, Ulrih NP. An overview of herbal products and secondary metabolites used for management of type two diabetes. Front. Pharmacol. 2017;8:1–14.
- Zhou J, Chan L, Zhou S. Trigonelline: a plant alkaloid with therapeutic potential for diabetes and central nervous system disease. Curr Med Chem. 2012;19:3523–31.
- Kalailingam P, Kannaian B, Tamilmani E, Kaliaperumal R. Efficacy of natural diosgenin on cardiovascular risk, insulin secretion, and beta cells in streptozotocin (STZ)-induced diabetic rats. Phytomedicine. 2014;21:1154–61.
- Broca C, Manteghetti M, Gross R, Baissac Y, Jacob M, Petit P, et al. 4-Hydroxyisoleucine: Effects of synthetic and natural analogues on insulin secretion. Eur. J. Pharmacol. 2000;390:339–45.
- Kumari K, Augusti KT. Antidiabetic and antioxidant effects of Smethyl cysteine sulfoxide isolated from onions (Allium cepa Linn) as compared to standard drugs in alloxan diabetic rats. Indian J Exp Biol. 2002;40:1005–9.
- Chuang C-Y, Hsu C, Chao C-Y, Wein Y-S, Kuo Y-H, Huang C. Fractionation and identification of 9c, 11t, 13t-conjugated linolenic acid as an activator of PPARalpha in bitter gourd (Momordica charantia L.). J Biomed Sci. 2006;13:763–72.
- Sasa M, Inoue I, Shinoda Y, Takahashi S, Seo M, Komoda T, et al. Activating effect of momordin, extract of bitter melon (Momordica Charantia L.), on the promoter of human PPARdelta. J Atheroscler Thromb. 2009;16:888–92.
- Kumar DB, Mitra A, Manjunatha M. Azadirachtolide. Pharmacogn Commun. 2011;1:78–84.
- Kim SH, Hyun SH, Choung SY. Anti-diabetic effect of cinnamon extract on blood glucose in db/db mice. J Ethnopharmacol. 2006;104:119–23.
- Choi H-J, Jang H-J, Chung T-W, Jeong S-I, Cha J, Choi J-Y, et al. Catalpol suppresses advanced glycation end-products-induced inflammatory responses through inhibition of reactive oxygen species in human monocytic THP-1 cells. Fitoterapia. 2013;86:19–28.