Insulin Resistance - Metabolic Disorder of the 21st Century

Insulin resistance is a disorder of the hormonal economy that affects every age group. However, there is an increasing incidence of insulin resistance in people with this disorder, especially in the pro-creative age with co-existing obesity and obesity, but not only in those with normal body weight but also with disorders in body structure. There are known factors that influence the development of insulin resistance, some of which are modifiable, so it is worth taking care of an appropriate lifestyle to prevent insulin resistance or slow down its progression. The sooner appropriate measures are taken, the less will the tissue resistance to insulin worsen and one can avoid diabetes and its complications in the future. Insulin resistance is a metabolic disorder caused by a reduced sensitivity of tissues (muscle, fat tissue) or hepatocytes (liver cells) to insulin produced by the beta cells of the pancreas, which in turn can lead to abnormal levels of glucose and insulin. Insulin resistance precedes the onset of type 2 diabetes and can contribute to the development of other diseases such as hypertension and cardiovascular disease. Studies have shown that a reduced insulin sensitivity occurs more than 10 years before the onset of type 2 diabetes (J.H. Warram et al. 1990). Initially, insulin resistance can be asymptomatic, but over time, various symptoms may appear. Symptoms of insulin resistance: - depression, - irritability, - memory and concentration problems, - drowsiness (especially after a meal), - chronic fatigue, - headaches, - joint pain, - feeling cold, - increased appetite for sweets, - frequent feeling of hunger - 2-3 hours after a meal, - difficulty losing weight, - skin changes (brown spots on the skin, e.g. on the neck, on the elbow bends). Long-term insulin resistance can lead to the development of the metabolic syndrome, i.e. the simultaneous presence of diabetes, lipid metabolism disorders, hypertension and visceral obesity. The diagnosis of insulin resistance is based on: - medical history (collection of information about symptoms and their evaluation), - positive family history (increased risk if insulin resistance or diabetes is present in the family), - the so-called glucose curve and insulin curve - simultaneous measurements of glucose and insulin levels at several time points - usually fasting, after 1 hour and after 2 hours from an oral glucose tolerance test, i.e. after drinking a solution of 75 g glucose, - the HOMA-IR index, calculated on the basis of fasting glucose and insulin levels: HOMA-IR = fasting insulinemia (mU/ml) × fasting glucose concentration (mmol/l) ÷ 22.5. Under physiological conditions, the HOMA-IR index is 1. The index value at which insulin resistance is diagnosed is controversial, but most specialists believe that it is a value above 2.

Insulin resistance results from a combination of genetic and environmental factors that interact with one another. There are a number of factors that increase the risk of insulin resistance, including: – occurrence in a family of insulin resistance or diabetes mellitus; – diagnosis of gestational diabetes or the birth of a baby with a body mass > 4 kg; – age – the risk of insulin resistance increases with age; – gender – men are more commonly affected by insulin resistance; – overweight and obesity – predispose to the development of insulin resistance; – amount of body fat – the risk of insulin resistance increases with an increase in body fat, especially in the abdominal region; – poor diet – providing the body with excess energy, mainly from animal fats and simple carbohydrates; – lack of physical activity – leads to a sedentary lifestyle; – stress – high levels of stress can affect the development of insulin resistance; – medications (e.g. rifampicin, olanzapine, tamoxifen) – can affect the development of insulin resistance; – thyroid disorders; – non-alcoholic fatty liver disease; – lipid metabolism disorders; – primary hyperparathyroidism; – elevated prolactin levels in the blood; – polycystic ovary syndrome.

The fundamental therapy for insulin resistance is a balanced diet that reduces the body's need for insulin and provides the essential nutrients required for a healthy weight, based on gender, body weight, age, and physical activity. A diet with a low glycemic index and load is recommended, as it stimulates the release of insulin the least. If excess body fat occurs, it should be reduced, which increases the sensitivity of tissues to insulin. In one study, the use of diet and increased physical activity resulted in a weight loss of 4-5 kg in patients, which reduced the risk of insulin resistance by up to 58% (J. Tuomilehto et al. 2001). It is important to remember that the basis is long-term action, i.e., maintaining constant changes in eating habits, not a return to previous habits once the goal has been achieved. The most important rules of the diet for insulin resistance are - Eat regular meals (the first meal should be eaten within an hour of waking up, the last one 2-3 hours before bedtime). - Limit or eliminate processed products, ready meals, and fast food (they provide less satiety than unprocessed food and have a negative impact on hormonal balance). - Limit or eliminate sugar (all forms of sugar are not recommended - including the ubiquitous glucose-fructose syrup, as it is precisely an excess of simple sugars that most disrupts the glucose-insulin balance. Sugar and glucose-fructose syrup are found in sweets, drinks, juices, fruit yogurts, jams, confitures, and also in less obvious products, such as cold cuts, sausages, spices, bread). - Limit or eliminate alcohol. - Limit salt intake to 6 g daily (which corresponds to 1 teaspoon, salt is present in many products, e.g., in cold cuts, cheese, bread). - Limit the consumption of saturated fatty acids (their sources are cream, butter, cheese, fatty meat, and its processing products, such as lard). - Increase water and herbal tea intake to at least 2 l daily. Coffee can also be consumed - it has a positive effect on blood glucose levels and increases the insulin sensitivity of tissues (M. A. Pereira 2006). - Increase the intake of vegetables and fruits (especially fresh ones). Ideally, vegetables should be included in every meal, as they are a source of vitamins, minerals, and fiber; fruits, especially with a low glycemic index, can be consumed as part of a well-balanced meal. Fruit eaten alone, however, raises blood glucose levels more than when consumed, for example, in yogurt (a source of protein) or with nuts (a source of fat). Fruits and vegetables containing anthocyanins - blueberries, currants, blackberries, cherries, strawberries, raspberries, beets, broccoli, carrots, spinach, almonds, and pumpkin seeds - improve the sensitivity of tissues to insulin. - Increase the intake of legumes (lentils, beans, chickpeas, soy, and their processing products). They are a good source of fiber, which slows down the absorption of carbohydrates, supports the improvement of the lipid profile, and increases the insulin sensitivity of tissues (D. Lau 2007). - Introduce whole-grain products (whole-grain pasta, brown rice, coarse grains - buckwheat, oatmeal, bulgur, whole-grain bread, whole-grain flour, oat flakes, etc.). However, it is important to control their quantity. - Introduce sources of unsaturated fatty acids (monounsaturated - olive oil, rapeseed oil, olives, avocado, nuts, almonds, sunflower seeds, pumpkin seeds, and polyunsaturated - salmon, herring, mackerel, flaxseed, flaxseed oil, meadowfoam oil). If their proportions in the diet are appropriate, they have anti-inflammatory effects, lower LDL cholesterol levels, and reduce the risk of heart and circulatory system diseases (K. Achremowicz, K. Szary-Sworst 2005). Studies conducted by N. Kasprzyk and M. Kręgielska-Narożna have shown that the use of balanced vegetarian or vegan diets based on unprocessed products with a low glycemic index, while simultaneously reducing the intake of saturated fatty acids, can have a therapeutic effect in patients with carbohydrate metabolism disorders. The currently popular ketogenic diet (high-fat diet) is not recommended in the diet therapy for insulin resistance, as it mainly contains saturated fatty acids, omega-6 fatty acids, and trans fats, which disrupt glucose homeostasis. It is very important to consume an adequate amount of protein, as it provides greater satiety, which is important in the context of weight loss. An adequate supply of this macronutrient, in combination with physical activity, is of great importance in building muscle mass. It contributes to reducing insulin resistance (J. W. Kennedy et al. 1999). To sensitize cells to insulin, in addition to changing the diet, it is necessary to introduce physical activity. In active people, the risk of insulin resistance may be up to 33-50% lower. Regular, moderate physical activity of at least 30 minutes, performed 5 times a week, is recommended. The activity should be adapted to age, health condition, and possibilities. Any form of movement has a positive effect on improving insulin sensitivity and regulating blood glucose levels. Anaerobic training has a positive effect on the activity of the enzyme AMPK (responsible for the uptake of glucose by muscle tissue) and the transport of glucose into cells independently of insulin. Regular strength training can increase insulin sensitivity by up to about 10-48%, lower blood glucose levels, and positively affect lean body mass. Exercises should preferably be performed during the day, about 3 hours after a meal. Morning exercises on an empty stomach are not recommended due to possible hypoglycemic states. However, sleep disturbances may occur in the evening. Everyone is different and should adapt both the type of physical activity and the time of its performance to their predispositions. If taking up additional physical activity is not possible, it is worth remembering that people with insulin resistance are recommended to walk 6000-10,000 steps daily. Changing lifestyle can reduce the risk of insulin resistance and diabetes.