Nutrition and Diabetes: What the Latest Science Reveals About This Relationship

Discover what the latest science reveals about this relationship.

By James Rodrigues Nutritionist | June 9, 2025

Introduction

Diabetes is a metabolic condition that affects millions of people worldwide, with numbers increasing each year. According to the International Diabetes Federation, approximately 537 million adults were living with diabetes in 2021, with this number projected to rise to 783 million by 2045.

In this worrying scenario, nutrition emerges as a fundamental pillar in both the prevention and treatment of this condition.

Recent research has revealed fascinating connections between our diet and diabetes, going far beyond simply restricting sugars. Discoveries in gut microbiota, nutrigenomics and functional foods are revolutionizing our understanding of how nutrition can influence glucose metabolism and overall metabolic health.

In this article, we present the latest scientific findings on the relationship between nutrition and diabetes, translating complex evidence into practical information that can make a difference in your health or that of your patients.

What is Diabetes and How Does Diet Affect It?

Diabetes is characterized by high blood glucose levels, resulting from problems in the production or action of insulin, a hormone responsible for facilitating the entry of glucose into cells. There are different types of diabetes:

• Type 1 diabetes: an autoimmune disease where the immune system attacks and destroys the insulin-producing cells in the pancreas. autoimmune disease where the immune system attacks and destroys the insulin-producing cells in the pancreas.

• Type 2 diabetes: characterized by insulin resistance, where cells do not respond adequately to this hormone. characterized by insulin resistance, where cells do not respond adequately to this hormone.

• Gestational diabetes: appears during pregnancy and usually disappears after delivery. appears during pregnancy and usually disappears after delivery.

• MODY (Maturity-Onset Diabetes of the Young): a rare genetic form caused by mutations in specific genes.

Diet directly influences blood glucose levels. Carbohydrates are converted to glucose during digestion, raising blood glucose levels. Proteins and fats have a smaller effect on blood glucose levels, but can affect insulin sensitivity in the long term.

Obesity, especially the accumulation of visceral fat, is strongly associated with the development of type 2 diabetes. Excess adipose tissue produces inflammatory substances that interfere with insulin signaling, contributing to insulin resistance and, consequently, hyperglycemia.

Gut Microbiota: The New Frontier in Diabetes Treatment

One of the most promising areas of diabetes research is the study of the gut microbiota – the trillions of microorganisms that inhabit our intestines. Recent research reveals that these tiny inhabitants can have a major impact on the development and progression of diabetes.

In type 2 diabetes, microorganisms in the intestine can trigger inflammatory responses that reduce insulin sensitivity. In type 1 diabetes, changes in the microbiota can contribute to autoimmune responses that attack insulin-producing cells.

Probiotics – live microorganisms that, when administered in adequate amounts, confer health benefits – are emerging as a promising strategy.

Studies show that certain probiotics can:

• Reduce systemic inflammation

• Reduce oxidative stress

• Improve the integrity of the intestinal barrier

• Increase insulin sensitivity

Foods rich in probiotics include plain yogurt, kefir, kombucha, and fermented vegetables like kimchi and sauerkraut. Prebiotics—indigestible fibers that feed beneficial bacteria—can be found in foods like garlic, onions, green bananas, chicory, and artichokes.

While the evidence is promising, the researchers stress that more studies are needed to determine exactly which strains of probiotics are most effective for each type of diabetes and at what dosages.

Functional Foods that Help Control Diabetes

In addition to probiotics, several functional foods – those that offer benefits beyond basic nutrition – have shown potential in controlling diabetes.

Olives and Olive Oil

Olives and olive oil, fundamental components of the Mediterranean diet, are rich in monounsaturated fats, mainly oleic acid, which improve insulin sensitivity. Hydroxytyrosol, the main phenolic compound present in olives, has potent antioxidant and anti-inflammatory properties.

Studies show that regular consumption of olive oil is associated with:

• Better glycemic control

• Reduction of systemic inflammation

• Protection of pancreatic β cells against oxidative stress

• Lower risk of developing type 2 diabetes

Papaya: A Surprising Ally

Papaya (Carica papaya) has emerged as a potential ally in controlling diabetes. Rich in vitamins A, C, E, B complex, minerals and several bioactive compounds, papaya has significant antioxidant and anti-inflammatory properties.

Research indicates that the bioactive compounds in papaya may:

• Reduce oxidative stress

• Improve insulin sensitivity

• Modulate intestinal glucose absorption

• Protect pancreatic β cells

Studies in animal models have shown that regular consumption of papaya can reduce fasting blood glucose and improve lipid profile in diabetic conditions.

Other Foods with Antidiabetic Properties

• Cinnamon: Improves insulin sensitivity and may reduce fasting blood glucose

• Nuts and seeds: Rich in healthy fats, fiber and magnesium, nutrients associated with better glycemic control

• Berries (blueberries, raspberries, strawberries): Contain anthocyanins that may improve insulin sensitivity

• Legumes: Rich in fiber and protein, they help stabilize blood glucose levels

• Green tea: Contains catechins that can improve glucose metabolism

Vitamin D: The Link Between Diabetes, Obesity, and Bone Health

Vitamin D, traditionally associated with bone health, has revealed surprising connections with glucose metabolism and diabetes. Recent research suggests that this vitamin may be an important link between osteoporosis, obesity and diabetes.

Vitamin D (1,25(OH)2D3) is a steroid hormone with a wide range of physiological functions in skeletal and non-skeletal tissues. In the context of diabetes, evidence indicates that vitamin D deficiency is associated with:

• Increased risk of developing type 1 and type 2 diabetes

• Worse glycemic control in patients already diagnosed

• Increased insulin resistance

• Increased systemic inflammation

The proposed mechanisms include:

1. Direct effect on the function of pancreatic β cells, which have receptors for vitamin D

2. Modulation of the immune response, especially relevant for type 1 diabetes

3. Reduction of systemic inflammation, improving insulin sensitivity

The main sources of vitamin D include:

• Sun exposure (15-30 minutes of direct exposure, several times a week)

• Fatty fish (salmon, tuna, sardines)

• Egg yolk

• Mushrooms exposed to UV light

• Fortified foods (some milks, yogurts and cereals)

For people with or at risk of diabetes, assessing vitamin D levels and supplementing when necessary, under medical guidance, can be important strategies for improving metabolic control.

Nutrigenomics: Personalizing Nutrition for Each Person

One of the most exciting advances in modern nutrition is nutrigenomics – the study of how foods affect our genes and how our genetic variations determine our response to nutrients. This science is revolutionizing diabetes care by enabling truly personalized nutritional approaches.

Nutrigenomics explains why standardized diets don’t always work for everyone. Some people respond better to low-carb diets, while others benefit more from diets rich in monounsaturated fats or higher in protein.

Genetic polymorphisms (variations in specific genes) can influence:

• How we metabolize carbohydrates

• Our insulin sensitivity

• How we process fats

• Our response to bioactive compounds in food

For example, people with certain genetic variants may have a more pronounced glycemic response to carbohydrates, while others may be more sensitive to the beneficial effects of omega-3 fatty acids or polyphenols.

In MODY (Maturity-Onset Diabetes of the Young) diabetes, a monogenic form of the disease, accurate identification of the genetic subtype has direct implications for treatment, including specific nutritional approaches.

Although nutrigenomic testing is not yet widely available, the future points to increasingly personalized eating plans based on individual genetic profiles, maximizing benefits and minimizing risks for each person with diabetes.

Nutritional Supplements: What Works and What's a Myth

With so many supplement options promising benefits for people with diabetes, it’s important to separate scientific evidence from marketing hype. Here’s a critical look at some of the most popular supplements:

Vitamin D

• Evidence: Moderate to strong for people with documented disabilities

• Potential benefits: Improved insulin sensitivity, reduced inflammation

• Recommendation: Supplementation only for people with low levels confirmed by tests

Chrome

• Evidence: Mixed, with some studies showing modest benefits

• Potential benefits: Improved insulin action

• Recommendation: There is no consensus for routine supplementation

Magnesium

• Evidence: Good for people with disabilities

• Potential benefits: Improved insulin sensitivity, reduced risk of type 2 diabetes

• Recommendation: Prioritize food sources (dark green vegetables, nuts, seeds, legumes)

Omega-3 Fatty Acids

• Evidence: Moderate for reducing inflammation, limited for direct glycemic control

• Potential benefits: Reduced triglycerides, improved cardiovascular health

• Recommendation: Consume oily fish 2-3 times a week; supplementation under guidance

Antioxidants (Vitamins C, E, etc.)

• Evidence: Limited when used alone

• Potential benefits: Reduction of oxidative stress

• Recommendation: Prioritize varied food sources

Cinnamon

• Evidence: Promising but still limited

• Potential benefits: Improved insulin sensitivity

• Recommendation: Can be included in the daily diet

It is important to note that supplements are not a substitute for a balanced and varied diet. Before starting any supplementation, consult a healthcare professional, as some supplements may interact with diabetes medications or have adverse effects in certain conditions.

Practical Tips for Healthy Eating in Diabetes

Based on the latest scientific evidence, here are practical recommendations for the nutritional management of diabetes:

Ideal Meal Composition

1. Plate Method: A simple way to plan balanced meals:

• ½ of the plate: non-starchy vegetables (green leaves, broccoli, tomatoes, cucumbers)

• ¼ of the plate: lean proteins (chicken, fish, tofu, legumes)

• ¼ of the plate: complex carbohydrates (brown rice, sweet potato, quinoa)

• Add a small serving of healthy fats (olive oil, avocado, nuts)

2. Prioritize fiber: Foods rich in fiber help stabilize blood sugar levels:

• Whole grains instead of refined grains

• Fruits with skin and pulp

• Legumes (beans, lentils, chickpeas)

• Assorted vegetables

3. Choose quality carbohydrates:

• Choose foods with a low glycemic index

• Combine carbs with protein and fat to reduce glycemic impact

• Control portion sizes

Feeding Times and Impact on Blood Glucose

• Regular meals: Avoid long periods of fasting

• Distribution throughout the day: Divide your food intake into 3 main meals and 2-3 healthy snacks

• Lighter dinner: Heavy meals at night can worsen glycemic control

• Consider chronotype: People with different circadian rhythms may benefit from different eating schedule patterns.

Smart Substitutions

• White rice → Brown rice, quinoa or grated cauliflower

• White bread → Wholemeal or naturally leavened bread

• Refined sugar → Small amounts of honey or fruit to sweeten

• Soft drinks → Water with lemon slices or herbal teas

• Processed snacks → Nuts, seeds or vegetable sticks with hummus

• Processed meats → Fish, chicken or vegetable proteins

• Whole milk → Skim milk or unsweetened plant-based drinks

Incorporate Functional Foods

• Add cinnamon to coffee, yogurt or oatmeal

• Include olives or extra virgin olive oil daily

• Consume papaya regularly as a dessert or snack

• Add anti-inflammatory spices like turmeric and ginger to your meals

• Try green tea between meals

Conclusion

The relationship between nutrition and diabetes is complex and multifaceted, involving much more than simply avoiding sugar. The latest research reveals the crucial role of the gut microbiota, the importance of specific functional foods, the potential of vitamin D, and the promise of nutrigenomics for personalized approaches.

What is clear is that there is no single diet that is ideal for all people with diabetes.

Diet must be personalized, considering the type of diabetes, genetic characteristics, individual preferences and sociocultural context.

Some key messages to take away:

1. The Mediterranean diet, rich in olive oil, vegetables, fruits, fish and whole grains, offers proven benefits for people with diabetes.

2. Probiotics and foods that promote a healthy gut microbiota may improve insulin sensitivity and reduce inflammation.

3. Functional foods such as olives, papaya and spices may offer specific benefits for glycemic control.

4. Vitamin D represents an important link between bone and metabolic health, deserving special attention.

5. The future points to increasingly personalized nutritional approaches, based on the individual genetic profile.

Remember that dietary changes should be part of an integrated approach, including regular physical activity, adequate blood glucose monitoring, medication when necessary, and psychological support. Always consult qualified health professionals for personalized guidance.

References:

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