on August 31, 2026
Diabetes mellitus encompasses a group of metabolic diseases characterized by chronic alterations in glucose homeostasis. In type 2 diabetes, the most common form in adults, hyperglycemia results from the progressive combination of insulin resistance and reduced secretory capacity of pancreatic β cells. Prolonged exposure to high blood glucose levels can contribute to the development of microvascular and macrovascular complications, affecting the retina, kidney, peripheral nervous system, and cardiovascular system.
The growing prevalence of diabetes represents one of the major global health challenges. The most recent epidemiological resources from the International Diabetes Federation confirm the continuous increase in the number of people living with diabetes and the growing importance of preventive strategies aimed at modifiable risk factors.
In type 2 diabetes, lifestyle intervention is not merely a complement to pharmacological therapy, but constitutes a structural component of disease prevention and management. Diet, body composition, physical activity, sleep quality, and reduced sedentary behavior act on multiple biological mechanisms involved in insulin resistance, visceral fat accumulation, metabolic inflammation, and endothelial dysfunction.
Diet and glycemic control
Diet directly influences both the magnitude of the postprandial glycemic response and the long-term energy balance and body composition. There is no single dietary model suitable for all patients with diabetes; the nutritional approach should be individualized based on metabolic characteristics, body weight, personal preferences, pharmacological therapy, and the presence of any complications.
The most recent recommendations of the American Diabetes Association emphasize the importance of dietary patterns that favor non-starchy vegetables, whole fruit, legumes, whole grains, nuts and seeds, quality protein sources, and appropriate dairy or plant-based alternatives, while limiting sugary beverages, sweets, refined grains, and highly processed foods.
Plant foods rich in fiber can help modulate the glycemic response through several mechanisms. Soluble fibers increase the viscosity of the intestinal contents, slowing the diffusion of nutrients and the absorption of carbohydrates. Fermentable fibers are also metabolized by the intestinal microbiota, producing short-chain fatty acids, molecules that may participate in the regulation of energy metabolism and the secretion of intestinal hormones involved in satiety and glucose homeostasis.
The physical structure of the food also plays an important role. A whole grain, a legume, or a whole fruit presents a different food matrix compared to readily available sugars or highly refined products. The rate of carbohydrate digestion and absorption therefore depends not only on the total amount of carbohydrates, but also on the presence of fiber, protein, lipids, and the structure of the food.
A particularly relevant goal in type 2 diabetes is postprandial glycemic control. After consuming foods containing starch, salivary and pancreatic α-amylase initiate the digestion of polysaccharides, while intestinal enzymes, including α-glucosidases, complete the conversion of oligosaccharides into absorbable monosaccharides.
The pharmacological principle of inhibiting these enzymes has been known for many years. Drugs such as acarbose reduce the rate of carbohydrate digestion and attenuate the postprandial rise in blood glucose. At the same time, numerous foods and plant compounds have been studied for their ability to interact with carbohydrate digestive enzymes.
However, it is essential to distinguish between the biological mechanism observed experimentally and clinical efficacy in the patient. Inhibitory activity demonstrated in vitro does not automatically imply a clinical benefit of equal magnitude in humans. The concentration of the active ingredient, the standardization of the extract, the timing of intake, the composition of the meal, and individual variability can significantly alter the final effect.
Physical activity: a true metabolic intervention
Physical activity acts directly on glucose metabolism. During muscle contraction, glucose uptake by skeletal muscle increases through mechanisms that do not depend exclusively on insulin. Exercise promotes the translocation of GLUT4 transporters to the cell membrane, increasing the muscle's capacity to utilize circulating glucose.
In the long term, regular training can improve insulin sensitivity, increase muscle mass, reduce visceral fat, and produce favorable effects on blood pressure and lipid metabolism.
Skeletal muscle represents the main peripheral compartment responsible for glucose utilization. Loss of muscle mass and function can therefore contribute to worsening insulin resistance, while maintaining or increasing muscle mass through resistance exercise can improve the body's metabolic capacity.
The American Diabetes Association 2026 recommendations indicate at least 150 minutes per week of moderate-to-vigorous aerobic activity for most adults with diabetes, spread over at least three days, generally avoiding more than two consecutive days without activity. Two or three weekly sessions of resistance exercise on non-consecutive days are also recommended. Frequently interrupting prolonged periods of sedentary behavior constitutes another important element of the metabolic strategy.
Available evidence also indicates that the combination of aerobic exercise and resistance training can offer superior glycemic benefits compared to using a single type of training. In people with type 2 diabetes, structured exercise programs of sufficient duration are associated with improvements in glycated hemoglobin even in the absence of major changes in body mass index.
This finding is particularly significant because it demonstrates that physical activity should not be considered exclusively as a tool for weight loss. Exercise directly modifies muscle metabolism, insulin sensitivity, and the distribution of energy substrates.
In individuals treated with insulin or medications that may promote hypoglycemia, physical activity must be planned taking therapy into account. The glycemic response to exercise can vary depending on the type of diabetes, therapy, intensity and duration of the activity, pre-exercise blood glucose level, and carbohydrate availability. Any changes in therapy or diet must therefore be agreed upon with the diabetologist.
Even in people with type 1 diabetes, physical activity offers important cardiovascular and functional benefits, but requires more careful management of glycemic variations. In children and adolescents, movement should be encouraged based on age, abilities, and individual preferences.
Reducing sedentary behavior to reduce metabolic load
An increasingly relevant aspect is the distinction between planned physical exercise and sedentary time. A person may formally meet the weekly physical activity recommendations and still spend many consecutive hours sitting.
Intermittent muscle contraction represents a metabolic stimulus that is lost during prolonged periods of inactivity. For this reason, regularly interrupting sitting and increasing daily movement can help improve metabolic control.
Diabetes and insulin resistance prevention therefore requires an approach that considers overall daily movement: walking, taking the stairs, moving on foot, and interrupting sedentary behavior are behaviors that can be integrated with structured exercise.
Phaseolus vulgaris and α-amylase inhibition
Legumes are a natural source of protein, fiber, and bioactive compounds. In the case of Phaseolus vulgaris, the common bean, particular interest has been focused on the presence of proteins capable of interacting with α-amylase.
Standardized extracts of Phaseolus vulgaris are primarily studied for their ability to reduce starch digestion. In the presence of effective α-amylase inhibition, some of the starch may be digested more slowly, potentially attenuating the postprandial glycemic and insulin response.
Extract standardization is particularly important. The mere botanical presence of beans in a formulation does not allow one to infer the biological activity of the product. The concentration of active proteins and the declared enzymatic activity are essential elements for assessing the consistency between composition and rationale for use.
A study conducted in humans by Spadafranca and colleagues observed the effects of a Phaseolus vulgaris extract on glycemic-metabolic control and appetite in healthy subjects, highlighting changes in the postprandial response related to the intake of the extract. The results contribute to the biological rationale for the use of standardized extracts, although they do not authorize considering these products as substitutes for diabetes therapy.
The possible interest of natural α-amylase inhibitors concerns above all the modulation of the response to starch-rich meals. The expected effect inevitably depends on the quantity and quality of the carbohydrates consumed. A product with anti-amylase activity cannot compensate for chronic caloric excess or neutralize the metabolic effects of an overall unbalanced diet.
Berberine: carbohydrate and lipid metabolism
Berberine is an alkaloid found in several plant species, including Berberis aristata. In recent years, it has received considerable attention for its possible effects on carbohydrate and lipid metabolism.
Among the most studied mechanisms is the activation of AMP-activated protein kinase, commonly referred to as AMPK. This system works as a sensor of cellular energy status and influences numerous metabolic processes, including the utilization of glucose and lipids.
Effects of berberine on insulin receptor expression, hepatic lipid metabolism, and the regulation of LDL lipoprotein receptors have also been described. The work of Kong and colleagues helped clarify the hypocholesterolemic mechanism of berberine, highlighting an increase in LDL receptor expression through a mechanism different from that of statins.
Available clinical evidence suggests a potentially favorable effect on both glycemic control and some lipid parameters. A recent systematic review with meta-analysis published in 2024 included 50 randomized studies with a total of 4,150 participants. Berberine was associated with improvements in fasting blood glucose, postprandial blood glucose, and several lipid parameters; when used together with hypoglycemic therapy, the meta-analysis also observed a reduction in glycated hemoglobin.
These data must be interpreted carefully. The quality and heterogeneity of the studies, the different formulations, dosages, and studied populations make it improper to consider berberine equivalent to standard pharmacological therapy.
Particular caution is necessary in patients treated with hypoglycemic medications. A compound capable of altering blood glucose can indeed add to the effects of medications and increase the risk of excessively low blood glucose levels. Furthermore, berberine may present pharmacological interactions, and its intake should be evaluated by the physician or pharmacist when the patient is following chronic therapies.
The issue of bioavailability is also relevant. Berberine has limited oral absorption, and the intestinal microbiota participates in its metabolic transformation. Some studies have highlighted the formation of more easily absorbable metabolites, including dihydroberberine. However, the differences between formulations do not allow the results obtained with one preparation to be automatically transferred to any product containing berberine.
Curcumin: inflammation, metabolism, and possible interactions
Curcumin is the main group of curcuminoids studied in Curcuma longa. The metabolic interest derives from its ability to interact with multiple molecular pathways involved in oxidative stress, inflammation, and cellular metabolism.
Low-grade chronic inflammation constitutes one of the biological mechanisms associated with visceral obesity and insulin resistance. In this context, the modulation of inflammatory pathways can represent a possible rationale for the study of curcumin.
A small clinical study evaluated the administration of curcumin in patients with type 2 diabetes treated with gliburide, observing changes in some glycemic and lipid parameters without episodes of hypoglycemia during the short observation period. The same study was also designed to evaluate possible pharmacokinetic and pharmacodynamic interactions.
However, the very limited number of participants and the short duration of the study prevent definitive conclusions. The most important finding from a clinical point of view is the need to consider the potential interactions between curcumin and medications. In diabetic patients on polytherapy, any supplementation should be evaluated within the overall therapeutic framework.
Gymnema sylvestre and the perception of sweet taste
Gymnema sylvestre is a plant traditionally used in several traditional medicine systems for sugar metabolism. Its most studied constituents include gymnemic acids.
One of the most characteristic aspects concerns the ability of some extracts to temporarily alter the perception of sweet taste. This phenomenon has been interpreted as a consequence of the interaction of gymnemic acids with receptors involved in the perception of sweet stimuli.
Mechanisms related to the modulation of intestinal glucose absorption and cellular metabolism have also been proposed. However, the gap between experimental results and real clinical efficacy must be clearly maintained.
The clinical evidence historically available for Gymnema sylvestre is less robust than that available for lifestyle interventions and pharmacological diabetes therapy. Even a previous systematic review by the American Diabetes Association noted that the studies available for Gymnema sylvestre were predominantly limited and not sufficiently robust to formulate definitive therapeutic conclusions.
The scientific interest in gymnema therefore remains linked above all to its biological rationale and the need for further randomized, controlled clinical studies conducted with adequately standardized extracts.
Fraxinus excelsior and glucose tolerance
Another plant extract undergoing clinical trials is that obtained from the seeds and fruits of Fraxinus excelsior. An interesting randomized, double-blind, placebo-controlled crossover study evaluated the extract in 22 overweight or obese, non-diabetic older adults within a moderately hypocaloric diet program.
The study observed favorable changes in several parameters related to the oral glucose load response and metabolic and adiposity markers. The authors therefore suggested a possible benefit of the extract in the context of metabolic alterations associated with overweight and reduced glucose tolerance.
The data is scientifically interesting but should not be overestimated. The number of participants was limited, and the study population did not include patients with overt diabetes. Therefore, larger and longer studies are needed before attributing a defined clinical role to the extract in the treatment of diabetes.
Dandelion and metabolism: tradition and limitations of the evidence
Taraxacum officinale, commonly known as dandelion, is traditionally used primarily to support digestive function and hepatobiliary physiology.
The presence of inulin and other plant compounds also makes the plant interesting from the perspective of the relationship between diet, microbiota, and metabolism. Inulin belongs to the category of fermentable fibers and can be utilized by specific populations of intestinal bacteria.
However, it is necessary to avoid automatically attributing a clinically proven antidiabetic effect to dandelion. The experimental evidence and biological mechanisms are not sufficient on their own to consider dandelion a therapy for hyperglycemia.
The use of the plant also requires caution in individuals with biliary tract diseases. In the presence of gallstones or other hepatobiliary conditions, the use of plant preparations with activity on digestive function should be discussed with a physician.
Salvia officinalis: preliminary clinical data
Salvia officinalis contains numerous phenolic and terpenic compounds that have been studied for their biological activities. A randomized clinical trial evaluated a sage extract in patients with type 2 diabetes and dyslipidemia who were already undergoing pharmacological therapy.
After two months, the study observed statistically significant improvements in fasting blood glucose, postprandial blood glucose, glycated hemoglobin, and several lipid profile parameters in the treated group compared to the placebo group. The trial involved a total of 100 participants, and the extract was evaluated as an add-on to pharmacological therapy.
In this case too, the concept of an “add-on” is fundamental. The results do not demonstrate that sage can replace metformin, insulin, statins, or other prescribed medications, but they suggest a possible interest for further studies.
Nutraceuticals and diabetes: supplementation does not mean replacement
The growing interest in plant extracts and nutraceuticals reflects the attempt to simultaneously address several aspects of metabolic syndrome: blood glucose, insulin resistance, body weight, lipids, and inflammation.
This approach is biologically interesting because type 2 diabetes rarely represents an isolated alteration of blood glucose. Visceral overweight, hypertension, hypertriglyceridemia, reduced HDL cholesterol, and vascular function alterations frequently coexist.
However, the concept of nutraceutical support must be distinguished from that of pharmacological treatment. A dietary supplement is not intended for the diagnosis, prevention, or treatment of a disease and should not induce the patient to independently modify the prescribed therapy.
Caution is particularly important in diabetes because the improvement of blood glucose, when achieved through multiple simultaneous interventions, may make an adjustment of the therapy necessary. The uncontrolled combination of hypoglycemic drugs, insulin, and extracts potentially active on carbohydrate metabolism can increase the risk of hypoglycemia.
The most solid rationale for the management of type 2 diabetes therefore remains an integrated approach. Quality of diet, control of energy intake when necessary, maintenance of muscle mass, regular physical activity, reduction of sedentary behavior, and adherence to the prescribed therapy constitute the foundations of the intervention.
Plant extracts can be of interest when they have a clearly identified and standardized composition and when they are used with realistic expectations. The presence of a studied active principle does not, in fact, equate to the demonstration of therapeutic efficacy for any formulation or in any patient.
The future of diabetes prevention and management will be increasingly oriented toward personalization. The response to diet, exercise, and nutraceutical interventions depends on genetics, body composition, residual pancreatic function, intestinal microbiota, pharmacological therapy, and lifestyle.
In this perspective, diabetes management cannot be reduced to the simple search for a substance capable of lowering blood glucose. The real goal is to intervene on the metabolic system as a whole, improving insulin sensitivity, preserving muscle function, reducing cardiovascular risk, and promoting sustainable long-term behaviors.
Important note: nutritional strategies and physical activity represent fundamental components of diabetes management, while supplements and plant extracts may eventually be considered as complementary support. In the presence of diagnosed diabetes, and particularly during insulin or hypoglycemic drug therapy, any supplementation must be evaluated with a physician or diabetologist due to the risk of interactions and changes in blood glucose.
Essential bibliography
American Diabetes Association Professional Practice Committee. Facilitating Positive Health Behaviors and Well-being to Improve Health Outcomes: Standards of Care in Diabetes—2026. Diabetes Care. 2026.
International Diabetes Federation. IDF Diabetes Atlas, 11th Edition. 2025.
Lindström J, et al. The Finnish Diabetes Prevention Study. Diabetes prevention studies through lifestyle modification.
Umpierre D, et al. Physical activity advice only or structured exercise training and association with HbA1c levels in type 2 diabetes. JAMA. 2011.
Spadafranca A, Rinelli S, Riva A, et al. Phaseolus vulgaris extract affects glycometabolic and appetite control in healthy human subjects. British Journal of Nutrition. 2013;109:1789-1795.
Wang and colleagues. Effects of administering berberine alone or in combination on type 2 diabetes mellitus: a systematic review and meta-analysis. Frontiers in Pharmacology. 2024.
Kong W, Wei J, Abidi P, et al. Berberine is a novel cholesterol-lowering drug working through a unique mechanism distinct from statins. Nature Medicine. 2004.
Zhang Y, Li X, Zou D, et al. Treatment of type 2 diabetes and dyslipidemia with the natural plant alkaloid berberine. Journal of Clinical Endocrinology & Metabolism. 2008.
Zulet MA, Navas-Carretero S, Lara y Sánchez D, et al. A Fraxinus excelsior L. seeds/fruits extract benefits glucose homeostasis and adiposity related markers in elderly overweight/obese subjects. Phytomedicine. 2014;21:1162-1169.
Neerati P, Devde R, Gangi AK. Evaluation of the effect of curcumin capsules on glyburide therapy in patients with type-2 diabetes mellitus. Phytotherapy Research. 2014;28:1796-1800.
Kianbakht S, Nabati F, Abasi B. Salvia officinalis Leaf Extract as Add-on to Statin Therapy in Hypercholesterolemic Type 2 Diabetic Patients: a Randomized Clinical Trial. International Journal of Molecular and Cellular Medicine. 2016;5:141-148.
