Science-backed eating to prevent type 2 diabetes and its complications
Science-backed eating can prevent type 2 diabetes and its complications
The food we eat is one of the most significant factors associated with whether we develop type 2 diabetes.[1] Analysis of the Global Burden of Disease Study 2021 revealed that the global burden of type 2 diabetes attributable to diet across 204 countries increased significantly between 1990 and 2021, resulting in a 92% increase in years lost due to premature death and years living with illness or disability and a 28% increase in death.[2] Major contributors to the increasing burden were a high intake of processed red meat and sugar-sweetened beverages.
A high-fat (particularly high-saturated fat),[3] low-fiber,[4] ultra-processed food (UPF) diet changes the gut microbiome,[5] and this has an adverse effect on the genetic, metabolic, immune and inflammatory pathways.[6],[7],[8]
The trillions of microbes in our guts, collectively known as the gut microbiota, contribute their genes to the gut microbiome. People who have type 2 diabetes show unhealthy changes in the composition and activity of their gut microbiota (referred to as gut microbiota dysbiosis).[9]
One consequence of unhealthy changes to the gut microbiota and the associated gut microbiome is insulin resistance. Body cells lose their sensitivity to respond to insulin, resulting in high blood sugar levels and type 2 diabetes.
High blood sugar levels cause disability and death
High blood sugar levels are a sign and a consequence of type 2 diabetes. They result in oxidative stress, which damages blood vessels supplying all parts of the body, and eventually leading to diabetes-associated disability and death.
In larger blood vessels, oxidative stress promotes atherosclerosis, which restricts and can completely obstruct the blood supply, leading to:[10]
· Coronary artery disease, manifesting as angina, heart attack, heart failure, arrhythmias, and sudden death.
· Cerebrovascular disease, resulting in various types of stroke and dementia.[11]
· Peripheral vascular disease, resulting in leg pain and cramping on exercise, impaired wound healing and infections, ulceration, gangrene, and amputation.
In smaller blood vessels, oxidative stress results in leaking blood vessels and restricted or obstructed blood supply, leading to:
· Retinopathy affecting the eye, resulting in a variety of visual disorders and blindness.
· Nephropathy affecting the kidneys, resulting in loss of protein from the body (causing fluid retention and ankle swelling), high blood pressure, impaired kidney function, and kidney failure.
· Neuropathy affecting the nerves, resulting in a variety of abnormal sensations and loss of sensation in the feet, legs, hands and arms, foot ulceration, infections, constipation, diarrhea, urinary problems, fluctuating heart rate and blood pressure.
Foods that increase the risk of type 2 diabetes
Ultra-processed foods (UPFs)
The risk of type 2 diabetes is increased by around 50% by a high intake of UPFs or red meat.
Ultra-processed foods are produced by industrial processes from ingredients that are not necessarily recognisable foods. They are usually high in saturated fat, sugar, and salt, low in fiber and nutrients, and contain additives such as emulsifiers and flavor enhancers not typically used in a home kitchen.[12] They include ready-made bread, pizza, crisps, pastries, cookies and cakes, fast foods, snacks, many breakfast cereals, soda and sports drinks, processed meats, instant foods, candies, sweets and ice cream.
National surveys show that UPFs contribute approximately half of total calorie intake in high-income countries such as the US,[13] UK, many European countries, Canada and Australia.[14] In 2025, the US National Health and Nutrition Examination Survey (NHANES) data reported for August 2021–August 2023 UPFs provided 62% and 53% of calories consumed by young people aged 1–18 years and people aged 19 years and older, respectively.[15] People eat UPFs because they are cheap, taste good, have a long shelf life and require little preparation.
Over the past 20 years, studies have shown that a high intake of UPFs increases the risk of type 2 diabetes by around 50%:
· In 2008, high consumption of low-calorie soft drinks, sugar-sweetened beverages, burgers and sausages, crisps, snacks, and white bread and low consumption of medium- and high-fiber breakfast cereals and wholemeal bread among 7339 civil servants in the UK Whitehall II study significantly increased the risk of type 2 diabetes. Higher intake increased the risk. People in the top quartile for this diet had a 51% higher risk of type 2 diabetes.[16]
· In 2020, a 6-year follow-up study of 104,707 participants in the French NutriNet-Sante Prospective Cohort reported a 15% higher risk of type 2 diabetes for every 10% increase in UPF and a 5% higher risk per 100g/day increase in UPF.[17]
· In 2021, a 12-year follow-up study of 20,060 participants in the Spanish SUN project reported a 53% higher risk of type 2 diabetes for those in the highest tertile of UPF consumption compared with participants in the lowest tertile, with a significant dose-response relationship.[18]
· In 2021, a 5.4-year follow-up study of 21,730 participants of the UK Biobank (2007–2019) reported that those in the highest quartile of UPF consumption had a 44% higher risk of type 2 diabetes compared with participants in the lowest quartile, with a significant 12% higher risk for every 10% increase in UPF consumption.[19]
· In 2022, a systematic review and meta-analysis of 18 studies including over 1 million people reported that compared with people who do not consume UPFs, those who consume a moderate- or high-UPF diet have a 12% and 31% increased risk of type 2 diabetes, respectively.[20]
· In 2022, a 3.4-year follow-up study of 70,421 participants of the Dutch Biobank reported a 10% increase in UPF consumption was associated with a 25% higher risk of type 2 diabetes and four different habitual UPF consumption patterns. A pattern high in cold savory snacks and a pattern high in warm savory snacks were associated with an increased risk of type 2 diabetes; a pattern high in traditional Dutch cuisine was not associated with type 2 diabetes incidence and a pattern high in sweet snacks and pastries was associated with a lower risk of type 2 diabetes. The authors conclude that there is a need to further clarify how different UPF consumption patterns are related to type 2 diabetes.[21]
· In 2024, a combined analysis of seven cohorts showed the risk of type 2 diabetes was 12% higher for every 10% increase in UPF consumption.[22][23][24]
· In 2025, a dose-response meta-analysis of 12 prospective cohort studies reported that participants with the highest UPF consumption had a 48% higher risk of type 2 diabetes than participants with the lowest intake, with a 14% increased risk for every 10% increase in UPF consumption.[25]
· In 2025, a systematic review and updated meta-analysis of 14 studies with nearly 700,000 participants reported that compared with people with the lowest intake of UPFs, those with the highest intake had a 24% increased risk of type 2 diabetes, with a 13% increased risk for every 10% increase in UPF consumption. In addition, data from four studies suggested that high UPF consumption may be associated with the complications of type 2 diabetes.[26]
See https://firstlinemedicalcommunications.co.uk/UPFs for more information about UPFs.
Unprocessed and processed red meat
A study of 216,695 participants (81% females) from the Nurses’ Health Study (NHS), NHS II, and Health Professionals Follow-up Study providing nearly 5.5 million person-years of follow-up reported that total, processed, and unprocessed red meat intakes were positively and approximately linearly associated with higher risks of type 2 diabetes. Comparing the highest to the lowest quintiles, total red meat, processed red meat, and unprocessed red meat increased the risk of type 2 diabetes by 62%, 51%, and 40%.[27]
A huge global study of data of nearly 2 million adults in 31 cohorts confirmed that meat, particularly processed meat and unprocessed red meat, increases the risk of type 2 diabetes across populations. Greater consumption was associated with an increased incidence of type 2 diabetes, with an increased risk of 10% for every 100g/day of unprocessed red meat and 15% for every 50g/day of processed meat.[28]
Avoid UPFs and restrict red meat to less than two servings/week
Widespread consumption of UPFs, including processed meat, is playing a key role in the global tsunami of ill-health and disability, overwhelming health services financially and logistically.
Dietary modification is the cornerstone in preventing type 2 diabetes.[29] A healthy UPF-free, low-saturated fat, high-fiber, nutrient-dense diet such as the Mediterranean diet or a healthy plant-based diet can improve insulin sensitivity. But policymakers have little appetite to fight the huge corporations making and marketing unhealthy foods.
However, we as individuals can all make our own informed decisions about our diets to protect ourselves from and manage type 2 diabetes. This blog aims to help you take control of your diet and by providing you with science-backed guidance to plan UPF-free nutrient-dense meals in appropriate portion sizes to achieve your body weight, blood sugar, blood pressure, and blood lipid goals, and to delay or prevent the complications of diabetes.[30]
Science-backed nutrients, foods, and diets to eat to prevent type 2 diabetes
Fiber
Dietary fiber is a carbohydrate that cannot be digested and is found only in plants. It may be soluble in water (as in fruits, vegetables, and oats) or insoluble (as in nuts, legumes, wholegrains); most high-fiber foods contain a mixture of both.[31] Soluble fiber slows digestion, insoluble fiber has a laxative effect and accelerates the transit of gut contents.[32]
A high intake of fiber lowers the risk of type 2 diabetes[33] and promotes changes in the composition of gut microbiota that improve glucose metabolism and insulin sensitivity in people with type 2 diabetes.[34]
· A 2013 systematic review and meta-analysis of 11 studies calculated that there is a 6% reduction in risk of type 2 diabetes for every 7g/day of dietary fiber.[35]
· In 2019, the Lancet published a systematic review and meta-analysis of 135 million person-years of data from 185 prospective studies and 58 clinical trials with 4635 adult participants. It showed that a daily intake of between 25g and 29g of fiber lowers the risk of developing type 2 diabetes 15–30% compared to a low daily intake. The risk appeared to be even less for those who had higher daily intakes of fiber (over 29g/day).[36]
A high fiber intake helps prevent many common diseases, including type 2 diabetes, but most people have a low intake.[37] This is mainly due to the high consumption of low-fiber UPF replacing high-fiber foods.
Consuming wholegrains instead of low-fiber refined grains such as white bread and white rice and eating more high-fiber foods can help lower the risk of type 2 diabetes.[38]
High-fiber foods feature prominently in healthy diets such as the Mediterranean diet, the DASH diet, the MIND diet, a plant-based diet, a flexitarian diet, the EAT-Lancet diet and a Nordic diet.
See https://www.firstlinemedicalcommunications.co.uk/Fiber to find out more about the recommended daily intake of fiber, its health benefits, and the fiber counter and tracker app we publish on the App Store.
Wholegrains
Wholegrains comprise the whole grain kernel — the outer layer of bran, the middle layer of endosperm and the core germ layer. In contrast, refined grains are produced by removing the bran and the germ layers, which removes fiber, vitamins, minerals, healthy fats and antioxidants. Refined grains are all grains that do not include the bran and germ, for example white flour and white rice.
Wholegrains include cereal grains, pseudocereals, ancient grains and processed wholegrain.
Large observational-prospective and cross-sectional studies consistently demonstrate that a higher intake of wholegrains is associated with a lower risk of type 2 diabetes. People who consume two-to-three 60–90g/day servings of wholegrains have a 21–32% lower risk of type 2 diabetes than those who rarely or never consume wholegrains. This amount can be achieved by substituting at least half of refined cereal foods in the normal diet with wholegrains.[39]
A 2022 systematic review and dose–response meta-analysis of 11 prospective cohort studies involving 463,282 participants found that those with the highest wholegrain intake had a 21% decrease in risk of type 2 diabetes compared with participants with the lowest intake. A higher intake of wholegrain lowered the risk of type 2 diabetes by 23%.[40]
150g/day of wholegrains prevents type 2 diabetes and consuming multiple wholegrain types is more effective than consuming just one type. These were the findings of a 2024 systematic review and dose–response meta-analysis of 10 prospective cohort studies involving 473,019 participants and 37 randomized controlled trials with 3136 participants. The authors concluded that 150g/day of wholegrains should be recommended to prevent type 2 diabetes.[41]
Find out more about 19 different wholegrains from our website https://www.firstlinemedicalcommunications.co.uk/wholegrains
Polyphenols
Polyphenols are powerful antioxidants in plants, protecting them from damage caused by infections, infestations, ultraviolet light and oxidative stress. They include flavonoids and anthocyanins.[42] Several hundred polyphenols are found in food and sources include wholegrains, legumes, nuts, seeds, vegetables, spices, fruits, cocoa, olive oil, tea, coffee and wine.
Many studies suggest that polyphenol-rich diets are associated with a significant decrease in the risk of developing type 2 diabetes.[43] They have a “prebiotic” effect on the gut, promoting beneficial gut bacteria and inhibiting potential pathogenic species,[44][45] and their antioxidant activity protects against oxidative stress. However, the effects of specific polyphenols on glucose metabolism and their possible role in the prevention of type 2 diabetes are yet to be defined.
Flavonoids are a class of polyphenols, and the subclasses that help prevent type 2 diabetes are flavanols and anthocyanins.[46]
· Flavanols have a prebiotic-like effect on the gut microbiome, modulating its composition and function to promote healthy metabolic pathways and immune responses and inhibit low-grade chronic inflammation.[47] Rich sources are bananas, apples, blueberries, peaches and pears.[48]
· Anthocyanins have antioxidant and anti-inflammatory effects, produce the vivid colors of many fruits and vegetables, and improve the proportion of beneficial gut microbiota.[49] Good sources of anthocyanins are red, purple, blue and black fruits and vegetables, and red wine.[50]
A higher intake of anthocyanins and anthocyanin-rich fruit, particularly blueberries, apples and pears, lowers the risk of type 2 diabetes. This was the 2012 finding of a follow-up study in the US of data for 70,359 women in the Nurses’ Health Study (NHS, 1984–2008), 89,201 women in the NHS II (1991–2007), and 41,334 men in the Health Professionals Follow-Up Study (1986–2006) who did not have diabetes at baseline. Over 3.5 million person-years of follow-up, 12,611 cases of type 2 diabetes were documented. No significant associations were found for total flavonoid intake or other flavonoid subclasses.
A subsequent 2013 analysis of data for 66,105 women in the NHS (1984–2008), 85,104 women in the NHS II (1991–2009) and 36,173 men in the Health Professionals Follow-up Study (1986–2008) reported that a higher intake of blueberries, grapes, and apples was significantly associated with a lower risk of type 2 diabetes whereas greater consumption of fruit juice was associated with a higher risk.[51]
Fruits
The health benefits of different fruits depend on their content of specific nutrients. Not all fruits are the same.
Find out more about 38 different fruits from our website at https://www.firstlinemedicalcommunications.co.uk/fruits
Cocoa and dark chocolate
Cocoa, the key ingredient in chocolate, is a rich source of antioxidant polyphenols,[52] especially flavanols, and consuming chocolate (particularly dark chocolate rather than milk or white chocolate) improves insulin sensitivity.[53] This beneficial effect on insulin sensitivity was demonstrated in 2012 by a systematic review and meta-analysis of 42 randomized controlled trials involving 1297 participants, which showed significant reductions in insulin resistance.[54]
Other studies have also produced the type of results everyone likes to see.
· A 2017 meta-analysis of 14 prospective studies involving over half a million participants showed chocolate intake was associated with a lower risk of type 2 diabetes with a peak protective effect at 2 servings of 30g/week, which lowered the risk by 25%. No benefit was observed when increasing consumption above 6 servings/week.[55]
· A 2024 prospective cohort study involving over 100,000 participants investigated the associations between dark, milk, and total chocolate and the risk of type 2 diabetes. The data were sourced from the Nurses’ Health Study (NHS, 1986–2018), the NHS II (1991–2021), and the Health Professionals Follow-Up Study (1986–2020). Participants consuming at least 5 servings of 1oz (28g)/week of dark chocolate (but not milk chocolate) showed a significant 21% lower risk of type 2 diabetes.
Coffee
Higher coffee consumption lowers the risk of type 2 diabetes, with each additional cup of coffee lowering the risk of type 2 diabetes by 10%.[56] However, adding sugar or artificial sweetener significantly decreases the beneficial effect. This was the finding of a 2025 analysis of three large prospective studies in the US — the Nurses’ Health Study (NHS, 1986–2020), NHS II (1991–2020), and the Health Professionals Follow-up Study (1991–2020) — providing over 3.5 million person-years of follow-up and 13,281 cases of incident diabetes.
Monounsaturated fat (MUFA) from plants
The difference between monounsaturated, polyunsaturated and saturated fatty acids lies in the type of bonding between their carbon atoms, which determines their molecular shape and their different effects on body metabolism and the gut microbiota.
In saturated fatty acids, all bonds between the carbon atoms are single — that is the bonding is saturated — whereas in unsaturated fatty acids the bonds are not all single: in monounsaturated fatty acid (MUFA), there is one double bond between the carbon atoms and in polyunsaturated fatty acid (PUFA), there are at least 2 double bonds.[57]
A 2025 review of the effect of different types of fatty acid on the gut microbiota concluded, based on the limited amount of data available from 33 studies in animals and humans, that a high-fat diet including long-chain saturated fatty acids, industrial trans fatty acids, and cholesterol is associated with detrimental changes in the composition of gut microbiota and decreases short-chain fatty acid (SCFA) production. SCFAs such as acetate, butyrate, and propionate contain only 2–6 carbon atoms, are produced when gut microbiota ferment fiber, and promote gut health. In contrast, MUFAs and omega-3 PUFAs have the potential to enhance beneficial bacteria and their metabolites.[58]
It matters whether the food source of a MUFA is a plant or an animal.
An investigation into the effect of MUFA from plant sources and MUFA from animal sources revealed that a high intake from animal sources was associated with a 34% increased risk of type 2 diabetes, whereas a high intake from plant sources was associated with a 13% lower risk. These were the results of an analysis of data from over 50,000 women in the Nurses’ Health Study (NHS, 1990–2016), over 60,000 women in the NHS II (1991–2017) and 29,497 men in the Health Professionals Follow-up Study (1990–2016) who did not have type 2 diabetes at baseline. The study involved nearly 3.3 million person-years of follow-up and the identification of 13,211 cases of incident type 2 diabetes.[59]
The richest plant sources of MUFA per serving are macadamia nuts providing 15g/25g serving (59g/100g) of which 74% is oleic acid and extra virgin olive oil (EVOO)/olive oil containing 10g/tablespoon serving (69g/100g) of which 98% is oleic acid.
Other rich plant sources of MUFA are:
· Canola oil — 9g/tablespoon serving (63g/100g) of which 96% is oleic acid.
· Avocado — 8g/80g serving (98g/100g) of which 93% is oleic acid.
· Peanut oil — 8g/tablespoon serving (57.1g/100g) of which 97% is oleic acid.
These data are provided by the U.S. Department of Agriculture, Agricultural Research Service, Beltsville Human Nutrition Research Center. FoodData Central. [Internet]. [cited 25 July 2025]. Available from https://fdc.nal.usda.gov/)
Other good plant sources of MUFA are hazelnuts, pecan nuts, sesame oil, almonds, brazil nuts, peanuts, pistachios and cashew nuts.
Oleic acid is a MUFA that appears to enhance insulin sensitivity[60] and has a key role in lowering the risk of type 2 diabetes.
Extra-virgin olive oil (EVOO)
Not all fats and oils are the same. They vary in the composition of their building blocks (fatty acids) and their content of polyphenols and other bioactive components.[61]
A score-based system has been proposed to rank oils and fats based on their nutritional value.[62] In this system, EVOO ranks first with a score of 100 because of its unique healthful nutritional profile resulting from the way it is produced. The olives are mechanically pressed within hours of harvesting without the use of heat or chemicals, and if the temperature remains under 27°C throughout the EVOO qualifies as cold-pressed. The process is designed to ensure the purity of EVOO and preserve its flavor and nutritional content, which includes high levels of:
· Oleic acid (a monounsaturated fatty acid)
· Linoleic acid (an omega-6 fatty acid)
· α-linolenic acid (an omega-3 fatty acid)
· Tocopherols (vitamin E)
· Hydroxytyrosol (a powerful antioxidant in olives and olive oil)
· A wide variety of polyphenols including flavonoids.[63]
The oils with the next highest scores in the score-based system are
· Common olive oil and flaxseed oil (which both score 86)
· High-oleic acid sunflower oil and sesame oil (which both score 82).
All plant oils other than margarine and coconut oil (which scores 0) rank above the 50th percentile.
Unlike other plant oils, olive oil is an integral part of the Mediterranean diet, providing approximately two-thirds of the vegetable fat in the diet. Many components of the Mediterranean diet including olive oil,[64][65] fiber, and polyphenols have been shown to lower the risk of type 2 diabetes.
EVOO is particularly recommended for frying foods using good frying practices (i.e. maintaining a temperature at less than 180°C, pre-drying foods and minimizing oil reuse) due to its stability and health benefits arising from its high content of MUFA (oleic acid) and its minor antioxidant components, like tyrosol and hydroxytyrosol.[66] Fried foods can be safely included in a balanced diet if consumed in moderation.
In 2017, a systematic review and meta-analysis of four cohort studies including nearly 16,000 people with type 2 diabetes and 29 clinical trials investigated the link between olive oil intake and the risk of type 2 diabetes. Compared with people with the lowest intake, those with the highest intake had a 16% lower risk of type 2 diabetes, and a dose–response analysis revealed that each 10g/day increase in olive oil was associated with a 9% lower risk of type 2 diabetes.
The authors of a larger dose-response meta-analysis published in 2025 using data from four cohort studies and six randomized controlled trials (RCTs) carried out between 2011 and 2023 concluded that their study “provided direct and strong evidence” that olive oil consumption can lower the risk of type 2 diabetes.[67] Participants with the highest intake of olive oil compared with those who never or almost never consumed olive oil had a 13% lower risk of type 2 diabetes in the cohort studies and a 22% lower risk in the RCTs. The reduction in risk was higher for participants over 50 years of age and for those who consumed EVOO rather than common olive oil, and the authors suggest that 10–20g/day of olive oil may be effective for preventing and managing type 2 diabetes.
Find out more about EVOO from our website https://www.firstlinemedicalcommunications.co.uk/EVOO
Potassium
Potassium is an electrolyte with a critical role in fluid balance and blood pressure, nerve function, muscle (including heart) contraction, and many metabolic processes. Rich dietary sources of potassium per serving are potato, beans, lentils, and banana. Good sources are fish, avocado, leafy greens, and wholegrains.
A meta-analysis of seven studies found that a dietary potassium intake of between 3000 and 5000mg per day is associated with apparent benefit against the development of type 2 diabetes.[68] The daily Adequate Intake of potassium recommended by the US Dietary Guidelines for Americans[69] is 3400mg for men and 2600mg for women if they do not have impaired potassium excretion as a result of a health condition such as kidney disease or medication. A higher intake is required for women who are pregnant or breastfeeding depending on age.
See https://www.firstlinemedicalcommunications.co.uk/Potassium to find out more about potassium recommended daily intake, its effect on health, and the potassium counter and tracker app we publish on the App Store.
Magnesium
Magnesium plays a key role in hundreds of metabolic reactions including glucose utilization and insulin signaling,[70] but many people worldwide do not consume enough. Good sources of dietary magnesium per serving are wholegrains, legumes, leafy greens, nuts and seeds, and oily fish — all components of a Mediterranean diet.
A systematic review of 26 studies evaluated the effect of magnesium intake on the risk of type 2 diabetes. Compared to the lowest magnesium intake, the highest level of intake was associated with a 22% lower risk and the risk decreased 6% for each 100mg/day of magnesium intake.[71]
The US Dietary Guidelines for Americans Recommended Daily Allowance for magnesium is 420mg for men and 320mg for women over 30 years of age. A higher intake is required for women who are pregnant or breastfeeding, depending on age.
See https://www.firstlinemedicalcommunications.co.uk/Magnesium to find out more about magnesium recommended daily intake, its effect on health, and the magnesium counter and tracker app we publish on the App Store.
Vegetables
Observational studies have suggested that different types of vegetable have different effects on lowering an individual’s risk of type 2 diabetes.[72]
A 12-year follow-up study of data for 8009 participants in the Australian Diabetes, Obesity and Lifestyle Study showed that green leafy, cruciferous, and yellow/orange/red vegetables may improve glucose tolerance, and that a diet rich in green leafy vegetables might improve insulin sensitivity. Higher intakes of legumes, alliums, and potatoes that were not fries or chips were not associated with any of the glucose or insulin outcomes.[73]
Evidence from randomized controlled trials (RCT) has been limited. A 2025 RCT was therefore carried out to evaluate the effect of daily consumption of cruciferous vegetables vs root/squash vegetables on control of blood sugar. Eighteen adults without diabetes had 2-week dietary interventions of 300g/day cruciferous soup (active group) and root/squash soup (control) with standardized lunch/dinner meals separated by a 2-week washout. This was the first RCT to compare the relative contribution of vegetable types added to the diet on glycemic outcomes in adults without diabetes. It showed that cruciferous vegetables improved control of blood sugar after a meal compared with root/squash vegetables.
The health benefits of vegetables are attributed to their fiber content and their diverse content of phytochemicals including polyphenols and glucosinolates (which have a bitter taste),[74] but not all vegetables are the same.
Find out more about over 70 different vegetables from our website at https://www.firstlinemedicalcommunications.co.uk/Veg
Nuts and seeds
Nuts and seeds, 1–2 servings/day, are an integral part of the Mediterranean diet. Not only do they lower the risk of cardiovascular disease and coronary heart disease,[75] but they also appear to lower the risk of stroke and type 2 diabetes.
The scientific evidence supporting the effect of nuts and seeds in lowering the risk of type 2 diabetes, is, however, limited and conflicting.
· Some, but not all, large studies have found that higher consumption of total nuts, walnuts, and peanuts is significantly associated with a lower risk of type 2 diabetes.[76]
· A small study of 61 patients with type 2 diabetes and 74 controls found consumption of nuts and seeds was associated with a 76.3% lower risk of type 2 diabetes.[77]
· A 2019 review of seven meta-analyses showed that fasting plasma glucose (FPG) was significantly decreased with nut consumption compared with control diets.[78]
· A 2019 systematic review of five randomized controlled studies (RCTs) involving 371 adults at risk of diabetes, three investigating the effects of whole nuts and two the effects of ground flaxseed showed that:
· 56g/day of walnuts for 6 months had no effect on FPG or HbA1c.
· 7g/day of pistachios or 60g/day of almonds for 4 months improved FPG and fasting plasma insulin, insulin resistance, cellular glucose uptake in lymphocytes and pancreatic beta-cell function.
· 13g/day of flaxseed for 3 months improved FPG, fasting plasma insulin, and insulin resistance in one study, but had no effect on glucose metabolism in a second study.[79]
· A 2021 systematic review and meta-analysis of eight observational studies concluded that total nut, peanut, or tree nut consumption had no effect on the risk of type 2 diabetes.[80]
· A 2022 umbrella review of systematic reviews and meta-analyses reported mixed associations between consumption of nuts and risk of type 2 diabetes.[81]
It is possible that some, but not all, nuts and seeds may lower the risk of type 2 diabetes. All nuts and seeds are not the same and contain different amounts of fat:
Find out more about 21 different nuts and seeds from our website at https://www.firstlinemedicalcommunications.co.uk/nuts/and/seeds
Mediterranean diet
In 2011, the PREDIMED randomized controlled trial (RCT) of 418 nondiabetic participants demonstrated that those assigned to a Mediterranean diet EVOO (1 liter/week) or nuts (30g/day) had a 52% lower risk of type 2 diabetes after 4 years compared with those in a low-fat diet control group. In all study arms, increased adherence to the Mediterranean diet lowered the risk of type 2 diabetes.[82]
A Mediterranean diet contains more fruit, vegetables, nuts, fish and olive oil than other diets designed to prevent cardiovascular disease[83] and provides all essential nutrients, vitamins, and minerals and hundreds (if not thousands) of antioxidant and anti-inflammatory phytochemicals.
In 2017, a review of the results of numerous studies reported adherence to a Mediterranean diet lowered the risk of type 2 diabetes by 20–23%.[84]
In 2022, an updated systematic review and dose–response meta-analysis of 16 prospective cohort studies involving over 750,000 subjects concluded:
· The greatest adherence to the Mediterranean diet is significantly associated with a 17% lower risk of type 2 diabetes.
· Each 1-score increase in the Mediterranean diet score is associated with a 3% lower risk.
· Even modest adherence to the Mediterranean diet is linked to a lower risk.[85]
Find out more about the Mediterranean diet. See https://www.firstlinemedicalcommunications.co.uk
Plant-based diets
Plant-based diets are based on fruits, vegetables, legumes, wholegrains, nuts, and seeds, with minimal or no intake of animal products and may be vegetarian, vegan, or flexitarian,[86] and include differing quantities of unhealthy UPFs.
Although plant-based diets have been recommended to lower the risk of type 2 diabetes, not all plant foods are beneficial: a diet that emphasizes healthy plant foods with no unhealthy UPFs lowers the risk of type 2 diabetes by 34%, BUT a diet that is high in less healthy UPF plant foods INCREASES the risk by 16%.[87]
A plant-based diet index (PDI) was developed for a study of 7100 participants to differentiate:
· Healthy plant foods — wholegrains, fruits, vegetables, nuts, legumes, vegetable oils, tea, and coffee.
· Less healthy plant foods — fruit juices, refined grains, potatoes, sugar-sweetened beverages, and sweets/desserts.
· Animal foods — animal fats, eggs, dairy products, fish and seafood, meats, and other animal-based items.
The healthiest plant-based diets had the highest PDI scores, and people with a PDI score in the top tertile had a 30% lower risk of type 2 diabetes than those with a PDI score in the bottom tertile.[88]
Science-backed foods to eat to lower the risk of complications of type 2 diabetes
Dietary interventions in patients with type 2 diabetes can help prevent the long-term complications of early death from any cause including heart attack and stroke, retinopathy, nephropathy, neuropathy, mood disorders and male infertility.[89]
Which diets are most effective?
Key findings of two literature reviews, one published in 2023 that reviewed clinical studies of different diets for diabesity, which is the intersection of obesity and diabetes[90] and one published in 2025 that reviewed systematic reviews, meta-analyses, and original research articles[91] were:
· The Mediterranean diet and a healthy plant-based diet have beneficial effects for preventing and treating type 2 diabetes, weight loss, improvements in blood lipids, and overall lowering of risk of cardiovascular complications.
· Low-carbohydrate diets control blood sugar and decrease insulin resistance but are difficult to maintain in the long-term.
· High-protein, low-fat diets improve satiety and promote weight loss.
· Intermittent fasting improves metabolism and promotes weight loss.
These findings highlight the need for personalization and tailored dietary approaches.
A 2024 systematic review and network meta-analysis evaluated studies using different dietary approaches published up until September 2024. The analysis included 31 trials involving 3096 people and compared eight diet interventions — the Mediterranean, moderate-carbohydrate, low-carbohydrate, vegetarian, low-glycemic index/load, low-fat, high-protein and control diets. The Mediterranean diet was found to be the most efficient dietary intervention for controlling blood sugar, and the low-carbohydrate diet was the best for managing overweight and obesity.
Significant reductions in fasting plasma glucose can be achieved in patients with type 2 diabetes by eating a high-MUFA rather than a high-carbohydrate (CHO) or high-PUFA diet. This was demonstrated by a meta-analysis into the effect of 24 studies with 1460 participants comparing high-MUFA to high-CHO diets and four studies with 44 participants comparing high-MUFA to high-PUFA diets.
A calorie-restricted diet can reduce body weight and improve heart and metabolic health. In addition to any required calorie restriction, a plant-based, Mediterranean, low-carbohydrate (<26% total calories), or a high-protein diet, and plenty of omega-3 fatty acids can also improve heart health and metabolic health in individuals with type 2 diabetes.[92] Metabolic health refers to all the chemical processes that keep us alive and include energy production so we can think, move, grow and carry out all daily functions, and building and repairing body cells, tissues, and organs.
Science-backed eating to lower risk of death from any cause
Fiber, healthy protein, fruit and veg, high-quality carb
The studies detailed below have shown that the risk of death from any cause for people with type 2 diabetes can be lowered by:
· Increasing fiber intake — a higher fiber intake was associated with a significantly lower risk of all-cause mortality in a 2024 analysis of data for 3259 adults with prediabetes or diabetes from the 2011–2018 US National Health and Nutrition Examination Survey (NHANES).[93]
· Adopting a healthy protein dietary pattern high in proteins from legumes, fruits, nuts, seeds, and fish, and low in red meat protein — in contrast, an unhealthy protein dietary pattern rich in red meat and egg proteins and low in fish and poultry proteins appears to be associated with a higher risk of death among adults with type 2 diabetes.[94] This was the conclusion of a 2024 analysis of patterns of protein intake and mortality in 4646 adults with type 2 diabetes taking part in the 1999–2018 US NHANES.
· Eating plenty of fruit and vegetables — a 2025 study analyzed nine prospective cohort studies reporting risk estimates for the association between total fruit and vegetable intake and death from any cause involving over 75,000 participants with diabetes and 7590 deaths. It demonstrated that an additional 200g/day of fruit and vegetables was associated with a 26% and 14% lower risk of death from any cause.[95]
· Replacing 3–5% of calories provided by low-quality carbohydrate or saturated fat with high-quality carbohydrate, plant-based protein, or unsaturated fat is associated with a 14–37% lower risk of death — a 2022 analysis of data for 9793 adults with prediabetes from the 1999–2014 NHANES reported that a healthy low-carbohydrate low-fat diet is associated with a lower overall mortality rate, while an unhealthy low-carbohydrate low-fat diet is associated with a higher overall mortality rate. Low-quality carbohydrate was defined as carbohydrate from refined grains, fruit juice, added sugar, potato, other starchy vegetables, and other carbohydrates.[96] High-quality carbohydrate was defined as carbohydrate from wholegrains, whole fruits, legumes, and nonstarchy vegetables.
Science-backed eating to lower risk of cardiovascular death
Fiber
A 2024 analysis of data from 3259 adults with diabetes or prediabetes from the 2011–2018 NHANES reported that every 1g/day increase in fiber intake up to 26.2g/day was associated with a 3% reduction in risk of cardiovascular death. No significant benefit was observed for a fiber intake above 26.2g/day.
Science-backed eating to lower risk of retinopathy
Mediterranean diet
A 2015 post-hoc 6-year follow-up of 3614 people with type 2 diabetes but no microvascular complications taking part in the PREDIMED randomized controlled trial reported that a Mediterranean diet enriched with EVOO may protect against diabetic retinopathy, with a relative reduction in risk of 43%.[97]
A 2025 systematic review and meta-analysis of 14 studies with 71,392 participants showed that people adhering to the Mediterranean diet had a significant 31% lower risk of diabetic retinopathy and concluded that a Mediterranean diet lowers the risk of diabetic retinopathy.[98]
Science-backed eating to lower risk of nephropathy
Fiber
A 2025 investigation into the relationship between dietary fiber intake and the risk of diabetic kidney disease among 4,520 adults with type 2 diabetes using US NHANES data from 2009 to 2018 showed that a dietary fiber intake over 13.96g/day exerted a notable protective effect against the development of diabetic kidney disease.[99]
Mediterranean diet
A 2024 prospective cohort study of 33,441 UK BioBank participants with hyperglycemia and no microvascular complications at baseline demonstrated that higher adherence to a Mediterranean diet is associated with a lower risk of diabetic nephropathy.[100]
A 2025 systematic review and meta-analysis of 14 studies with 71,392 participants showed that individuals adhering to the Mediterranean diet had a 15% lower risk of diabetic nephropathy.
Science-backed eating to lower risk of neuropathy
Magnesium
Magnesium plays a key role in hundreds of metabolic reactions including glucose metabolism and insulin signaling, but many people worldwide do not consume enough. Magnesium deficiency is therefore common and among people with type 2 diabetes it is associated with impaired nerve function and diabetic neuropathy.[101] Eat wholegrains, beans, leafy greens, nuts and seeds, and oily fish — all components of a Mediterranean diet — to avoid magnesium deficiency.
The US Dietary Guidelines for Americans1 Recommended Daily Allowance for magnesium is 420mg for men and 320mg for women over 30 years of age. A higher intake is required for women who are pregnant or breastfeeding depending on age.
See https://www.firstlinemedicalcommunications.co.uk/Magnesium to find out more about magnesium and its role in maintaining health and the magnesium counter and tracker app we publish on the App Store.
Science-backed eating to improve mood
Fiber
A 2023 randomized clinical study analyzed the effect of a high-fiber diet on the gut microbiota, serum metabolism and emotional mood of 17 patients with type 2 diabetes. The high-fiber diet improved glucose homeostasis and the emotional mood of patients and enriched the proportions of beneficial gut microbes, while the abundances of opportunistic pathogens were decreased.
Science-backed eating to improve male fertility
A healthy UPF-free diet
A 2023 review of dietary trends and the decline in male reproductive health highlighted its link to obesity and diabetes and an increase in total calories provided by UPFs. It advocated optimizing male fertility by replacing processed foods with unprocessed whole foods rich in micronutrients and phytonutrients.[102]
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Glossary
Alpha-linolenic acid (ALA) — an essential short-chain omega-3 polyunsaturated fat with 18 carbon atoms and three double bonds in plants (chia seeds, flaxseed, hemp seeds, walnuts, canola oil) that must be obtained from food because the human body is unable to synthesize it.
Antioxidant — a chemical that protects cells from damage by neutralizing free radicals produced by oxidative stress.
Docosahexaenoic acid (DHA) — a long chain omega-3 polyunsaturated fatty acid with 22 carbon atoms and 6 double bonds. It is essential for brain development and function and is especially important in pregnancy and infancy, and has many other functions. The human body can make some DHA from ALA, but the process is very inefficient with a conversion rate often less than 5%. Main dietary source is oily fish.
Eicosapentaenoic acid (EPA) — a long chain omega-3 polyunsaturated fatty acid with 20 carbon atoms and 5 double bonds. It has key anti-inflammatory and heart health effects and many other functions. The human body can make some EPA from ALA, but the process is very inefficient with a conversion rate often less than 10%. Main dietary source is oily fish.
Gut microbiome —the combined genetic code of the trillions of microbes (bacteria, viruses, and fungi) living in the gut containing many more genes than the human genome and coding for many diverse body functions including healthy metabolic, inflammatory and immune pathways. The microbes are collectively known as the gut microbiota.
Gut microbiota — the collective term for all microbes contributing to the gut microbiome.
Gut microbiota dysbiosis — unhealthy changes in the composition and activity of the gut microbiota.
Meta-analysis — the statistical analysis and combination of results from several similar studies (only two studies are necessary if they contain data on the same topic).
Network meta-analysis — the statistical analysis and combination of results from many studies to compare multiple treatments at the same time.
Oxidative stress — a situation in which adverse circumstances such as inadequate nutrition, infection or high blood sugar lead to the production of unstable molecules that can damage cells and contribute to disease.
Omega-3 polyunsaturated fatty acids — contain two or more double bonds with the first one three carbons from the methyl (omega) end of the carbon chain. They lower triglycerides and reduce inflammation for a healthy heart, play an essential role in brain development and function, and Support eye and nerve health.
Omega-6 polyunsaturated fatty acids — contain two or more double bonds with the first one six carbons from the methyl (omega) end of the carbon chain. They are key for cell membrane structure, growth and development, inflammation, blood clotting, and immunity. The ratio of omega-6 polyunsaturated fatty acids to omega-3 polyunsaturated fatty acids should be no higher than 4:1, but is much higher in Western diets and a high ratio is linked to a pro-inflammatory state.
Phytochemical — chemicals found only in plants that are not vitamins or minerals but can be beneficial for health. They include polyphenols, carotenoids (responsible for the yellow, red and orange colour of plants) and glucosinolates.
Randomized controlled trial (RCT) — a study in which participants are assigned at random to an intervention or treatment group and a control group and the outcomes of the two groups of participants are compared to see if the intervention or treatment has had an effect.
Systematic review — a review and analysis of the results of available studies aiming to answer a particular research question using an objective, reproducible method available studies that focused on a certain research question.[103]