Diabetes mellitus (DM) is one of the causes of the noninfectious pandemic of the 21st century. The number of patients diagnosed with prediabetes and diabetes increases every year. Every ten seconds, two new patients with this disease are added worldwide (Evseev,2019).

According to the World Health Organization (WHO), diabetes prevalence among adults aged 18 years and older increased from 7% in 1990 to 14% in 2022. In the same year, more than half (59%) of adults over 30 with diabetes were not taking medication to control their disease. The lowest treatment availability was recorded in low- and middle-income countries. In 2021, diabetes was the direct cause of 1.6 million deaths, with 47% of these deaths occurring in people younger than 70 years. A further 530,000 deaths were caused by diabetes-related kidney diseases. Elevated blood glucose levels are responsible for approximately 11% of deaths from cardiovascular disease. Since 2000, diabetes mortality has been rising (https://www.who.int/news-room/fact-sheets/detail/diabetes).

The modern lifestyle of the 21st century, characterized by hypokinesia, consumption of foods high in sugar, salt, fats, and synthetic additives, frequent exposure to stress, and unhealthy habits, leads to increased body weight, the development of metabolic syndrome (MS), and type 2 diabetes (DM2). Genetic and environmental factors also play a significant role in the spread of this pathology (Sharofova, 2019).

Diabetes mellitus, often simply referred to as diabetes, is a serious chronic progressive disorder characterized by increased blood glucose levels (hyperglycemia). This condition is associated with several comorbid states, such as vision deterioration, poor wound healing, erectile dysfunction, kidney failure, and cardiovascular diseases (Sharofova, 2019).

A diagnosis of diabetes is easy to establish if a patient has classical symptoms (for example, polyuria, polydipsia, polyphagia, and weight loss). Other symptoms that may indicate hyperglycemia include blurred vision, paresthesia of the lower extremities, or fungal infections, especially balanitis in men (American Diabetes Association, 2013).

Classification of diabetes mellitus

Diabetes mellitus type 1: This form of diabetes accounts for only 5–10% of cases and was previously known as insulin-dependent or juvenile diabetes. It is characterized by impaired insulin secretion due primarily to immunologically mediated destruction of pancreatic beta cells, resulting in absolute insulin deficiency. It usually manifests in childhood or adolescence, although an exception is LADA. LADA (latent autoimmune diabetes in adults): This is an autoimmune form of diabetes with onset in adulthood and a slower loss of insulin-producing capacity. Although it is classified as type 1 diabetes, it is not a distinct subtype. The presence of diabetes-associated autoantibodies (for example, antibodies against islet cells) is a strong predictor of progression to type 1 diabetes. The cause of this type is unknown, yet patients require daily insulin administration (Harreiter, Roden, 2023).

Diabetes mellitus type 2 represents about 90–95% of all diabetes cases and is characterized by insulin resistance combined with relative insulin deficiency. The main pathophysiological mechanisms include reduced ability of the liver to suppress glucose production and impaired glucose utilization in peripheral tissues, which leads to hyperglycemia. This type has a genetic predisposition and occurs more often in adults, but due to increasing obesity prevalence, it is also diagnosed in children. Major risk factors include obesity, older age, lack of physical activity, history of gestational diabetes, hypertension, and dyslipidemia (Brutsaert, 2023).

Type 2 diabetes often remains undiagnosed for a long time due to slow onset of symptoms, which increases the risk of serious macrovascular and microvascular complications. Although insulin resistance may be reduced through weight loss and appropriate treatment, complete normalization is rare. Therefore, a comprehensive approach to diagnosis, treatment, and prevention of this disease is essential (American Diabetes Association, 2002).

Gestational diabetes is a specific type of diabetes first diagnosed during pregnancy. This condition is characterized by altered glucose metabolism and can lead to adverse outcomes for both mother and fetus. GDM is usually reversible after delivery; however, women with a history of gestational diabetes have a markedly higher risk of developing type 2 diabetes later in life (Sharofova, 2019).

Besides types 1 and 2 diabetes and gestational diabetes, there are other specific forms linked to genetic beta-cell defects of the pancreas, endocrinopathies, infectious diseases, or exposure to chemicals and drugs. Impaired glucose tolerance (IGT) and impaired fasting glucose (IFG) are classified as prediabetic states. These represent an intermediate state between normal glycemia and diabetes mellitus, increasing the risk of progression to overt diabetes and its complications (Khardori, 2024).

The global diabetes epidemic is now a major public health problem. The World Health Organization (WHO) and the International Diabetes Federation (IDF) emphasize that the greatest increase in diabetes cases is seen in parts of the world lacking adequate capacity to provide necessary healthcare. In low- and middle-income countries and regions, where a high number of people have chronic health problems, diagnosis, treatment, and prevention of diabetes present a major challenge for public health systems (IDF, 2012).

Major risk factors for type 2 diabetes include an inappropriate diet characterized by consumption of large amounts of high-calorie, easily digestible foods and drinks, lack of physical activity or hypokinesia, increased body weight or obesity. Other factors include daily living and work activities associated with high psychoemotional stress. Harmful habits such as smoking and alcohol consumption also have a major impact, as does uncontrolled use of synthetic-origin drugs, especially abuse of hormonal drugs and antibiotics (Sharofova, 2019).

Diabetes mellitus treatment – the importance of nutrition
Treatment of diabetes mellitus requires a comprehensive approach that includes various forms of therapy, such as pharmacological treatment, physical activity, dietary measures, and other methods. Nevertheless, one of the key aspects in preventing and treating diabetes is nutrition. In this article, we analyze the essential role nutrition plays in diabetes mellitus management (Bekbenbetova, 2011).

Correct nutrition is a core component of diabetes management because it directly influences blood glucose levels, body weight, and overall patient health. A balanced diet helps control blood sugar, reduces the risk of complications, and improves the quality of life of people with diabetes. In addition, healthy eating can support weight loss in patients with overweight, which in turn increases tissue insulin sensitivity and improves overall metabolic profile (Evseev,2019).

Basic dietary rules for diabetes

  1. Restrict carbohydrates, especially easily digestible ones, and animal fats.
  2. Reduce dietary calorie intake, especially in overweight, to 2000–2300 kcal.
  3. Consume adequate amounts of proteins and vitamins.
  4. Adhere to a strict eating schedule – at the same time, five to six times daily, in small portions.

Foods whose consumption is not recommended in diabetes

Foods containing excess easily digestible and rapidly absorbable carbohydrates: sugar, sweets, jam, raisins, grapes, figs. These foods contain large amounts of glucose and sucrose, which are rapidly absorbed from the intestine into the blood, causing sudden rises in blood sugar. Fried, spicy, salty, heavily seasoned, and smoked foods, canned products, spices, and mustard should be markedly limited. Main meals should be prepared by boiling or baking. It is strictly forbidden to consume foods that contain both high fat and carbohydrate content: chocolate, cream ice cream, cakes, and cream-filled tarts (Bekbenbetova, 2011).

Foods whose consumption is recommended in diabetes

Vegetables whose carbohydrates are absorbed much more slowly in the gut than sugar: fresh cucumbers, tomatoes, cauliflower, cabbage, lettuce, zucchini, pumpkin, eggplant. Parsley, dill, and onions should also be included in the daily diet. Carrots and beets may be eaten more frequently, but the amount should be agreed in advance with the treating physician.
For diabetes, intake of about 300 grams of carbohydrates is recommended, primarily in the form of complex carbohydrates: 300 grams of rye bread; the remaining carbohydrate intake should come from vegetable and grain dishes (with limited use of whole grain cereals such as oats, buckwheat, and millet) (Bekbenbetova, 2011).

People with diabetes should ensure that their diet includes sufficient amounts of essential vitamins and minerals. These substances play a key role in maintaining vital bodily functions because they participate in many biochemical and physiological processes. Without adequate intake, other food components cannot fully perform their functions, leading to disruption of homeostasis and progressive worsening of health (Voloch et al., 2017).

Vitamins are divided into two groups: fat-soluble (A, D, E, K) and water-soluble (B groups and C). Fat-soluble vitamins require the presence of fats for absorption. For example, vitamin A supports improved vision and bone mass formation, vitamin D prevents rickets in children and osteoporosis in adults, vitamin E protects cells and tissues from damage, and vitamin K is involved in the blood clotting process. Water-soluble vitamins dissolve easily in water and are rapidly distributed throughout the body. B vitamins play an important role in metabolic processes and support the functioning of the nervous system, muscles, and heart. Vitamin C, in addition to its antioxidant properties, strengthens blood vessels and the immune system, helps prevent infectious and oncologic diseases, and also slows aging (Evert et al., 2019).

Minerals are an integral part of cells; they participate in their structure and regulation of many chemical reactions. For example, iron is essential for preventing anemia, and its deficiency can be compensated by consuming meat, eggs, fish, broccoli, and fortified foods. Calcium is vital for bone, teeth, and muscle health. Its deficiency in older age increases the risk of osteoporosis. Major calcium sources include dairy products, cabbage, and fish. Potassium regulates heart rhythm and ensures proper functioning of the cardiovascular system (Minari et al., 2023).

The glycemic index (GI) is an important tool in managing the nutrition of patients with diabetes. GI reflects the rate of rise in blood glucose after consumption of a specific food. Low-GI diets have proven effective in controlling diabetes and preventing its complications. Research results showed that use of low-glycemic diets contributes to reduced glycated hemoglobin (HbA1c), fasting glucose, body mass index (BMI), total cholesterol, and low-density lipoproteins (LDL). At the same time, these diets did not have a marked impact on fasting insulin levels, insulin resistance index (HOMA-IR), high-density lipoproteins (HDL), triglycerides, or insulin therapy requirements. Reductions in HbA1c and fasting glucose are associated with weight loss, underscoring the importance of low-glycemic diets for diabetes management and improvement of metabolic profile (Zafar et al., 2019).

For patients with insulin-dependent diabetes, a prescribed diet close to balanced nutrition is recommended, with total caloric intake of 2700–3000 kcal. The main portion of carbohydrates should be distributed over breakfast and lunch, because insulin is given before these meals. If insulin is given before dinner, it is important to ensure additional food intake at night to prevent hypoglycemia (Bekbenbetova, 2011).

Rational nutrition: structure and significance of the nutrition pyramid

Main principles of rational nutrition focus on meeting the body’s energy needs as well as providing the required amounts of macro- (proteins, fats, carbohydrates) and micronutrients (vitamins, minerals), including adequate water intake. To facilitate understanding and meal planning, a scheme in the form of a nutrition pyramid was developed, in which foods are grouped according to their nutritional value and recommended intake.
The base of the pyramid consists of carbohydrate-rich foods, including grains, grain products, bread, and potatoes. These foods provide energy and fiber to the body. Consumption of 6–11 portions per day is recommended. The second tier includes vegetables (3–5 portions) and fruits (2–4 portions). These foods are main sources of vitamins, minerals, and antioxidants that support health and immunity. The third tier comprises dairy products (2–3 portions) and protein foods such as meat, fish, legumes, eggs, or nuts (2–3 portions). These groups provide the body with needed proteins, calcium, and fatty acids (Voloch et al., 2017).

12 rules for healthy eating

  1. The diet should be as diverse as possible.
  2. Foods containing fiber (such as bread, cereals, pasta, rice, and potatoes) should be consumed at each meal.
  3. Different types of vegetables and fruits should be eaten several times per day (at least two portions of each type daily, except potatoes).
  4. Dairy products should be consumed daily, with preference for products low in fat and salt.
  5. Replacing fatty meat and meat products with fish, poultry, and legumes is recommended.
  6. Limit consumption of butter in porridge and on sandwiches.
  7. Limit consumption of sugar, sweets, confectionery products, sweet beverages, and desserts.
  8. Total intake of cooking salt should not exceed 6 g (one teaspoon) per day. The use of iodized salt is recommended.
  9. Do not exceed 2 portions (30 ml) of pure alcohol per day for men and 1 portion per day for women.
  10. Preparing meals by steaming, boiling, or baking is recommended.
  11. Normal body weight should correspond to recommended intervals determined by body mass index (BMI). BMI is calculated by the formula: weight (in kilograms) divided by height (in meters) squared. Normal value: 18.5–24.9.
  12. In order to maintain normal body weight, moderate physical activity is important in addition to rational nutrition practices (Howarth, 2019).

Discussion Diabetes mellitus is a serious and increasing public health problem, especially in urbanized countries where its prevalence is growing at an exceptional rate. It is estimated that by 2035 the number of people with diabetes worldwide will approach 600 million. To reduce the risk of diabetes-related complications and improve patients’ quality of life, it is essential to provide effective education and increase awareness of disease management (Ruszkiewicz et al., 2020).

Diabetes mellitus is a complex disease influenced by genetic, environmental, and lifestyle factors. Nutrition has a central role in prevention and treatment. Various epidemiological studies have shown that low-glycemic-index diets reduce the risk of hyperglycemia and related complications such as cardiovascular diseases and nephropathies (Ojo, 2019).

(Antwi, 2023) reported that precision nutrition represents a modern and innovative approach to preventing and treating obesity and type 2 diabetes, addressing gaps in traditional nutritional and lifestyle interventions. Results showed that precision nutrition is effective in improving risk factors for obesity and type 2 diabetes. This approach allows individualized dietary recommendations that consider genetic, phenotypic, and social factors. The greatest benefit was observed in positive behavior change among patients.
Many studies indicate that effective diabetes management is based on balanced diets that include restriction of quickly digestible carbohydrates and saturated fats, adequate vitamin and mineral intake, and regular consumption of low-glycemic-index foods (Hamdy, Barakatun-Nisak, 2016). Patient education is also a key factor, enabling better understanding of healthy lifestyle principles. In patients with type 2 diabetes who implemented these dietary recommendations, improvements in blood glucose levels, reduced glycated hemoglobin, and improved metabolic profile were observed (Reynolds, Mitri, 2024).

Conclusion

Diabetes mellitus is a serious global health issue whose prevalence continues to increase. Effective prevention and treatment of this condition requires a comprehensive approach that includes pharmacological therapy, physical activity, and proper nutrition. A low-glycemic-index diet, sufficient vitamin and mineral intake, and rationalization of dietary habits using the nutritional pyramid are key factors in controlling blood glucose and preventing diabetes-related complications.
Diabetes, especially type 2, is closely linked to lifestyle, including unhealthy diet, insufficient movement, and obesity, which requires focus on changing these factors through early diagnosis, patient education, and dietary interventions. It is also important to improve access to treatment in developing countries, where healthcare availability is often limited. The future should include further research on specific dietary interventions and treatment personalization to improve outcomes for patients with diabetes mellitus.

Authors:
Mgr. Anastasiia Ostafiichuk
prof. Mgr. MUDr. Erik Dorko, Phd., MPH, MBA
MVDr. Martina Hrubovčák Tejová

This work was supported by grants KEGA 001UPJŠ-4/2024 and 003UPJŠ-4/2024 of the Ministry of Education, Science, Research and Youth Affairs of the Slovak Republic.

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