How the regular consumption of olive oil polyphenols helps prevent the development of Type-2 Diabetes
1. A growing epidemic
The number of type-2 diabetes patients in the Western world is increasing rapidly. Globally, the International Diabetes Federation projects that the number of adults with diabetes will rise from 537 million in 2021 to 783 million by 2045, equalling to an increase of about 46%. Next to the diagnosed patients, there are millions of people who live with diabetes type-2 without knowing it. In the Netherlands alone, an estimated 400,000 people currently live with undiagnosed type-2 diabetes (Diabetes Fonds, 2026). Leaving this disease untreated is dangerous: it damages blood vessels, which significantly increases the risk of cardiovascular disease and Alzheimer’s disease.
Even in the absence of a diabetes diagnosis, elevated blood glucose levels already promote amyloid deposition (protein fragments forming plaques in the brain) and brain atrophy (loss of brain cells and connections, leading to shrinking brain tissue), resulting in a higher risk of developing Alzheimer’s. Cardiovascular health also deteriorates due to elevated blood glucose levels, because persistently high insulin levels (created in response to the glucose) damage small blood vessels, contribute to atherosclerosis, and reduce vessel flexibility. In short, chronically elevated blood sugar does not only pave the way to type-2 diabetes; it also significantly increases the risk of heart attacks, strokes, and cognitive decline.
The rapid rise of type-2 diabetes is closely linked to the modern Western diet, rich in refined carbohydrates and sugars, combined with a sedentary lifestyle. These conditions are ideal for the development of type-2 diabetes, and cardiovascular diseases. It is no surprise that cardiovascular diseases are the leading cause of death in the Western world. This blog explores what type-2 diabetes is, how it develops, and how a diet rich in olive oil polyphenols may help prevent this disease from developing, backed by scientific evidence
2. What is type-2 diabetes and how does it develop?
When you eat food that is high in carbohydrates such as white bread, sweets, soft drinks, or processed pasta, these carbohydrates are broken down into glucose in your body. As a result, your blood sugar level rises. This spike is regulated by a hormone called insulin, produced by the pancreas. Insulin acts as a key that unlocks cells to absorb glucose from the blood, either for immediate energy use or for storage as fat.
In a healthy body, the pancreas is finely tuned to detect glucose levels and produces exactly the right amount of insulin in response. This is known as insulin sensitivity. However, when someone regularly consumes sugar, this delicate mechanism becomes disrupted. Excess glucose molecules bind to proteins that normally signal the presence of sugar in the blood. Over time, the pancreas loses its ability to recognise these altered proteins and “thinks” it does not need to produce insulin. In medical terms, you then become insulin resistant.
The consequence is a vicious cycle: reduced insulin sensitivity leads to insufficient insulin production, which results in chronically elevated blood sugar, the hallmark of type-2 diabetes. Furthermore, the more carbohydrates consumed, the more fat is stored, increasing the likelihood of obesity, which itself is a major risk factor for type-2 diabetes. Most people develop this disease without being aware about it, because symptoms are often light and therefore ignored. However, without knowing it, the disease damages your body from within. It is therefore recommended to (regularly) test the sugar levels in your blood.
3. The mediterranean diet: a 50% risk reduction
The good news is that dietary choices can dramatically reduce the risk of developing type-2 diabetes. A landmark randomized controlled trial, the PREDIMED study, found that individuals following a Mediterranean diet with extra virgin olive oil as the primary source of fat had a 50% lower risk of developing type-2 diabetes compared to the control group (Salas-Salvadó et al., 2014). Furthermore, an observational cohort analysis from the same trial demonstrated that a high intake of olive oil polyphenols is associated with a decreased risk of diabetes in elderly persons at risk of cardiovascular disease (Tresserra-Rimbau et al., 2016).
The Mediterranean diet is the most researched diet of all diets worldwide. It comes from traditional eating patterns in countries like Greece, Italy, Portugal, and southern Spain. The core ingredients are vegetables in generous amounts, fruits (daily), legumes (lentils, chickpeas, and beans), whole grains (farro, bulgur, and whole wheat bread), nuts and seeds. Animal-based ingredients include fatty fish such as sardines, anchovies, salmon, and mackerel (which provide omega 3 fatty acids), dairy in moderation, poultry and eggs. Extra virgin olive oil is the golden thread running through everything, responsible for 60-70% of the fats of the diet.
The use of olive-derived compounds for managing blood sugar has a long history. For centuries, the leaves of the olive plant have been used in traditional medicine to treat diabetes (De Bock et al., 2013). Modern science is now uncovering why: systematic reviews have identified olive oil polyphenols, including luteolin, oleuropein, and hydroxytyrosol, as some of the most promising bioactive compounds against type-2 diabetes (Egbuna et al., 2021; Aumeeruddy & Mahomoodally, 2021).
But what exactly do these polyphenols do in the body? Below, we explore the four key mechanisms through which olive oil polyphenols help prevent and manage type-2 diabetes.
4. Four key mechanisms of olive oil polyphenols against diabetes
4.1 Olive oil polyphenols slow the breakdown of carbohydrates into glucose.
When polyphenol-rich olive oil is consumed together with carbohydrate-containing foods, the polyphenols interfere with glucose availability in the bloodstream through two complementary mechanisms: they inhibit the digestive enzymes that break carbohydrates down into glucose, and they block the transport proteins that carry glucose from the intestine into the blood. Together, these actions prevent the sharp blood sugar spikes that erode insulin sensitivity and pave the way for type-2 diabetes.
The 2 key enzymes involved in carbohydrate digestion are α-amylase, which breaks down starch into smaller sugar molecules, and α-glucosidase, which converts those smaller molecules into absorbable glucose. These are critical enzymes in carbohydrate digestion, and their inhibition by olive oil polyphenols is recognized as a therapeutic strategy for controlling blood sugar spikes (Bellesia & Tagliazucchi, 2022). Pharmaceutical drugs like acarbose work on exactly this principle, but olive oil polyphenols offer a natural alternative.
A study on phenolic-rich extracts from extra virgin olive oils found that both extra virgin olive oil extracts displayed stronger inhibitory activity against α-glucosidase than the commercial drug acarbose (Figueiredo-González et al., 2019). This is a remarkable finding: it means that the polyphenols naturally present in high-quality olive oil may outperform a widely prescribed diabetes medication in blocking this enzyme. The inhibitory activity was attributed primarily to oleuropein and ligstroside derivatives (polyphenols in olive oil). More recently, a 2025 study found that combinations of hydroxytyrosol and DHPG (another polyphenol) displayed inhibition of both α-glucosidase and α-amylase, significantly enhancing their individual efficacy (Rubio-Senent et al., 2025). This suggests that the natural blend of polyphenols found in extra virgin olive oil may be more effective than any single compound in isolation. The main conclusion: by consuming olive oil polyphenols with carbohydrate-containing foods, you are keeping the glucose absorption gradual so that the pancreas can maintain a healthy insulin response and the development of insulin resistance can be prevented.
4.2 Olive oil polyphenols delay the glucose absorption by the gut.
In addition to slowing the breakdown of carbohydrates (discussed above), olive oil polyphenols help regulate blood sugar levels through a second, complementary mechanism: they directly interfere with the transport proteins that carry glucose across the intestinal wall and into the bloodstream. Even after carbohydrates have been broken down into glucose, that glucose still needs to physically cross the barrier of the gut to enter the blood. Olive oil polyphenols act as gatekeepers at this barrier.
Intestinal glucose absorption relies on specific transport proteins, primarily SGLT1 (on the brush border membrane) and GLUT2 (on the basolateral side of intestinal cells). After a carbohydrate-rich meal, these proteins create a high-capacity absorption route that enables rapid glucose uptake and sharp blood sugar spikes. Olive oil polyphenols disrupt this process at multiple points. Research has shown that oleuropein, one of the polyphenols, significantly inhibits glucose transport through GLUT2 (Kerimi et al., 2018). Additionally, because oleuropein is a glycoside containing a glucose residue in its molecular structure, it can be taken up into intestinal cells via SGLT1, effectively competing with dietary glucose for the same transporter (Ferrara et al., 2023). This dual blockade slows the rate at which glucose crosses from the intestine into the blood.
These findings have been validated in humans. In a series of randomized, crossover, placebo-controlled studies, oleuropein attenuated postprandial (after-meal) blood glucose after sugar consumption in healthy volunteers (Kerimi et al., 2018). A randomized controlled trial in diabetes patients further showed that postprandial glucose was significantly lower when a sugar-rich meal was consumed with extra virgin olive oil compared to butter or a low-fat alternative (Bozzetto et al., 2016).
The net effect is that glucose enters the bloodstream more gradually after a meal, reducing the burden on the pancreas and protecting insulin sensitivity over time, which are key factors in preventing the progression toward type-2 diabetes.
4.3 Olive oil polyphenols stimulate insulin secretion from the pancreas.
Insulin is the hormone your body uses to regulate blood sugar. It is produced by specialised cells in the pancreas called beta cells. When blood sugar rises after a meal, these beta cells detect the change and respond by secreting insulin into the bloodstream. Insulin then acts as a key, unlocking cells in your muscles so they can absorb glucose from the blood and use it for energy. This process, known as insulin secretion, is essential for keeping blood sugar within a safe range. When beta cells become damaged or dysfunctional, insulin secretion reduces, blood sugar remains chronically elevated, and type-2 diabetes develops.
Olive oil polyphenols actively support and strengthen the body's insulin-producing mechanism. A randomized controlled trial found that olive oil polyphenols improved postprandial insulin release (Sánchez-Rodríguez et al., 2021). Laboratory research has uncovered how this works at the cellular level: in a study examining the effects of individual olive oil polyphenols on pancreatic beta cells, researchers found that hydroxytyrosol, tyrosol, and apigenin (polyphenols) promoted beta-cell proliferation and increased insulin biosynthesis, while apigenin and luteolin enhanced glucose-stimulated insulin secretion (Marrano et al., 2021). Animal studies support these findings: in a mouse model of diet-induced type-2 diabetes, a diet based on extra virgin olive oil reduced beta-cell deaths, increased the number of surviving beta cells, and normalised glucose-induced insulin secretion (Vidal et al., 2019).
In short, olive oil polyphenols support the pancreas in several ways: they help beta cells survive longer, they stimulate the production of more insulin, and they improve the beta cells' ability to release that insulin at the right moment. This makes polyphenol-rich extra virgin olive oil an active contributor to healthy blood sugar regulation.
4.4 Olive oil polyphenols promote glucose uptake in muscles and fat cells, where it can be used for energy rather than remaining in the bloodstream.
Once glucose enters the bloodstream, the body needs to move it into cells, particularly muscle and fat cells, where it can be used for energy. This process depends on a transport protein called GLUT4, which normally sits inside cells and only moves to the cell surface when triggered by insulin. In people developing insulin resistance, this signalling pathway falters and glucose remains in the blood.
Olive oil polyphenols stimulate the glucose uptake in muscles and fat cells. Research has shown that oleuropein enhances glucose uptake in muscle cells by activating AMPK, an enzyme that promotes the movement of GLUT4 to the cell membrane independently of insulin (Fujiwara et al., 2017). In other words, oleuropein helps muscle cells absorb glucose even when insulin signalling is impaired, mimicking the glucose-lowering effect of exercise. A meta-analysis reviewing 14 human intervention studies (with 594 participants) showed that the key olive oil polyphenols oleuropein, hydroxytyrosol, and tyrosol significantly reduced insulin levels, suggesting the body needed less insulin to manage glucose effectively (Frumuzachi et al., 2025). Studies in mice fed a high-fat diet confirmed that diets based on extra virgin olive oil improved insulin sensitivity and normalised glucose-induced insulin secretion (Vidal et al., 2019; Álvarez-Amor et al., 2021). The practical result: lower fasting glucose (the amount of sugar that is circulating in your bloodstream after you have not eaten for at least 8 hours) and a reduced HbA1c (average blood sugar over the preceding 2-3 months).
Several clinical trials have demonstrated direct reductions in fasting blood glucose from olive oil polyphenols in pre-diabetic and diabetic patients. A randomized controlled trial using oleuropein-enriched chocolate showed that blood glucose in type-2 diabetes patients increased significantly less after consumption compared to a control group (Del Ben et al., 2019). Another trial using TOTUM-63, a polyphenol-rich plant extract containing oleuropein, hydroxytyrosol, and luteolin, found decreased fasting blood glucose in prediabetic and newly diagnosed type-2 diabetes patients compared to placebo, positioning polyphenol supplementation as a promising prevention strategy (Sirvent et al., 2022).
Strikingly, an in vivo study in diabetic mice showed that hydroxytyrosol reduced fasting glucose to levels comparable with metformin, one of the most widely prescribed pharmaceutical treatments for metabolic syndrome (Cao et al., 2013). While human studies are needed to confirm this comparison, the finding underscores the potent glucose-lowering potential of olive oil polyphenols.
5. The Diabetes–Alzheimer’s connection
An increasingly recognised link between type-2 diabetes and Alzheimer’s disease makes the above findings even more relevant. Insulin resistance, the core feature of type-2 diabetes, has been identified as a key biological bridge between the two conditions. An in vitro study by Crespo et al. (2017) found that hydroxytyrosol protects brain cells by improving insulin sensitivity and restoring insulin signalling pathways that are disrupted in Alzheimer’s disease. This suggests that the protective effects of olive oil polyphenols extend to neuroprotection.
6. Conclusion
Type-2 diabetes is a largely preventable disease, and the evidence is compelling: a Mediterranean diet rich in olive oil polyphenols offers powerful protection against its development. From slowing carbohydrate breakdown to stimulating insulin secretion and even protecting against Alzheimer’s-related brain damage, the polyphenols in extra virgin olive oil work through at several mechanisms to keep blood sugar in check and maintain insulin sensitivity.
Interestingly, research suggests that the benefits of olive oil polyphenols may vary across populations. The meta-analysis by Frumuzachi et al. (2025) found that olive oil polyphenol interventions appear to be more beneficial for individuals with a BMI below 30, those with existing cardiometabolic disease, and non-Mediterranean populations. This may be because individuals already following a Mediterranean diet have higher baseline polyphenol intakes, making additional supplementation perhaps less impactful. For those on a typical Western diet, incorporating polyphenol-rich extra virgin olive oil rich in polyphenols could therefore represent an especially effective dietary intervention.
While more research, particularly large-scale, long-term human trials, is needed to fully quantify the effects above, the existing body of evidence from randomized controlled trials, meta-analyses, and laboratory studies provides a strong foundation. Choosing a polyphenol-rich extra virgin olive oil as your primary source of fat is one of the simplest, most evidence-based dietary changes you can make to protect yourself against type-2 diabetes and its devastating consequences.
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