Diabetes mellitus (DM) comprises a range of metabolic disorders characterized by high blood glucose levels caused by defects in insulin release, insulin action, or both. DM is a widespread condition that affects a substantial portion of the global population, causing high morbidity and mortality rates. The prevalence of this major public health crisis is predicted to increase in the forthcoming years. Although several drugs are available to manage DM, these are associated with adverse side effects, which limits their use. In underdeveloped countries, where such drugs are often costly and not widely available, many people continue to rely on alternative traditional medicine, including medicinal plants. The latter serves as a source of primary healthcare and plant-based foods in many low- and middle-income countries. Interestingly, many of the phytochemicals they contain have been demonstrated to possess antidiabetic activity such as lowering blood glucose levels, stimulating insulin secretion, and alleviating diabetic complications. Therefore, such plants may provide protective effects that could be used in the management of DM. The purpose of this article was to review the medicinal plant-based foods traditionally used for the management of DM, including their therapeutic effects, pharmacologically active phytoconstituents, and antidiabetic mode of action at the molecular level. It also presents future avenues for research in this field.

Diabetes mellitus (DM) comprises a range of metabolic disorders characterized by high blood glucose levels caused by defects in insulin release, insulin action, or both. DM is a widespread condition that affects a substantial portion of the global population, causing high morbidity and mortality rates. The prevalence of this major public health crisis is predicted to increase in the forthcoming years. Although, several drugs are available to manage DM, these are associated with adverse side effects, which limits their use. In underdeveloped countries, where such drugs are often costly and not widely available, many people continue to rely on alternative traditional medicine, including medicinal plants. The latter serve as a source of primary healthcare and plant-based foods in many low and middle-income countries. Interestingly, many of the phytochemicals they contain have been demonstrated to possess antidiabetic activity such as lowering blood glucose levels, stimulating insulin secretion and alleviating diabetic complications. Therefore, such plants may provide protective effects that could be used in the management of DM. The purpose of this article was to review the medicinal plant-based foods traditionally used for the management of DM, including their therapeutic effects, pharmacologically-active phytoconstituents and antidiabetic mode of action at the molecular level. It also presents future avenues for research in this field.

Astaxanthin (ASX) has been reported to reduce hyperglycemia by improving insulin secretion and insulin resistance. The present research aims to elucidate the antidiabetic effects as well as the mode of action of ASX, both in-vitro and in-vivo . Starch digestion, glucose diffusion, 2,2-Diphenyl-1-picrylhydrazyl (DPPH) were investigated in vitro, and oral glucose tolerance tests (OGTT), total residual unabsorbed sucrose contents in the gut, gastrointestinal (GI) motility were assessed in high-fat-fed (HFF) hyperlipidemic albino mice. Acute and chronic metabolic effects were evaluated by monitoring food and water intake, amount of urination and defecation. HFF-induced type 2 diabetic mice were treated for 33 days with ASX (30 and 60 mg/5 ml/kg b.w.) were used to assess chronic effects. In the in vitro study, ASX (1.6 - 1000 µg/mL and 40 - 5,000 µg/ml) decreased ( p< 0.001) enzymatic digestion of starch and glucose diffusion by 45.14% and 32.50%, respectively and also showed a significant inhibitory effect on the DPPH ( p< 0.001) over a concentration range (1.6 - 5000 µg/mL) of ASX. During the in vivo experiments, oral administration of ASX (30 - 60 mg/5 ml/kg b.w.) improved oral glucose tolerance ( p< 0.001) as well as significantly increased ( p< 0.01) residual unabsorbed sucrose contents in the six segments of the gut. In addition, ASX (30 - 60 mg/5 ml/kg b.w.) significantly enhanced GI motility (p<0.05) in albino mice. Furthermore, ASX (60 mg/5 ml/kg b.w.) reduced food and fluid intake, and the amount of urine and stool formation significantly ( p< 0.001) both in chronic and acute metabolic studies, accordingly. In a chronic study, ASX, at (30 and 60 mg/5 ml/kg b.w.), substantially lowered blood glucose, total cholesterol, VLDL, triglycerides, LDL cholesterol and also improved liver glycogen content. In conclusion, ASX shows effect on decreasing carbohydrate digestion, absorption, increasing GI motility, and inhibiting DPPH. Thus, ASX might be a potential drug for the management of diabetes and its complications.

Asparagus racemosus commonly known as Shatamull, is a medicinal plant with pharmacological applications documented in both Indian and British Pharmacopoeias and various traditional medicinal practices. Previous studies have reported that A. racemosus reduces hyperglycemia by enhancing insulin secretion. The aim of the current study was to assess the antihyperglycemic actions and explore the underlying mechanisms of action of A. racemosus utilizing in vitro carbohydrate digestion, glucose diffusion, glucose uptake, 2,2-Diphenyl-1-picrylhydrazyl (DPPH) and preliminary phytochemical screening. The inhibition of carbohydrate digestion was assessed using α-amylase and α-glucosidase enzyme assays. The effect on glucose diffusion was evaluated using cellulose ester dialysis tube. Subsequently, glucose uptake was measured in a yeast cell model at different glucose concentrations, and the antioxidant potential was evaluated by measuring DPPH radical scavenging activity. A. racemosus notably reduced ( p< 0.05, 0.001) glucose release during in vitro starch digestion by 37.69%, whereas glucose absorption decreased significantly by 33.60% ( p< 0.01–0.001). Additionally, the most significant enhancement ( p< 0.05, 0.001) in glucose uptake by 67.53%, was observed at 5 mM glucose concentration. Furthermore, it showed significant antioxidant activity by scavenging DPPH ( p< 0.01–0.001) radicals by 55.06%. Preliminary phytoconstituent screening indicated the existence of flavonoids, tannins, steroids, glycosides and saponins. In conclusion, A. racemosus shows an inhibitory effect on carbohydrate digestion and absorption, enhances glucose uptake and demonstrates significant DPPH radical scavenging activity, potentially due to the presence of naturally occurring phytochemicals. Thus, A. racemosus may contribute as a promising antidiabetic drug for the treatment of diabetes mellitus. More investigations are needed to determine the active compounds in A. racemosus that contribute to its antidiabetic effects.