What Is Insulin Resistance – A Comprehensive Guide. Everything You Need to Know If You’re Struggling with Insulin Resistance

The Role of Insulin

Insulin is one of the most important hormones regulating metabolism in the human body. It is produced by beta cells in the pancreas. Its secretion is primarily triggered by an increase in blood glucose levels, for example after a meal.

The mechanism of insulin action is based on binding to the insulin receptor, which is found on the surface of most cells in the body. Once insulin binds to the receptor, it activates a signaling pathway that enables:

• glucose transport into the cell,

• glucose storage – in the liver and muscles, insulin promotes glycogenesis, the process of converting glucose into glycogen (a storage form),

• inhibition of gluconeogenesis – insulin reduces the production of glucose from other compounds in the liver (e.g., amino acids).

What Is Insulin Resistance?

Insulin resistance is a metabolic disorder in which the body’s cells become less responsive to the effects of insulin.

In the past, insulin resistance was often underestimated because it doesn’t immediately cause severe symptoms and isn’t classified as a separate disease. This has changed in recent decades. Researchers now understand the critical role it plays in the development of chronic diseases such as type 2 diabetes, hypertension, and atherosclerosis.

Insulin Resistance in Poland

It’s estimated that in Poland, insulin resistance affects as many as 20–25% of adults. Among people with obesity, this percentage can exceed 50%. It is also increasingly observed in children and adolescents due to rising rates of obesity in this age group.

How Does Insulin Work and What Happens in Insulin Resistance?

In healthy conditions, insulin:

• Binds to insulin receptors on the surface of cells.

• Enables glucose to enter cells (mainly muscle, fat, and liver cells), where it is used for energy or stored as glycogen.

In insulin resistance:

• Insulin receptors on cells don’t respond properly to insulin.

• Glucose isn’t effectively transported into cells, leading to elevated blood sugar levels (hyperglycemia).

• The pancreas compensates by producing more insulin, resulting in hyperinsulinemia (excess insulin in the blood).

Types of Insulin Resistance

Scientific literature distinguishes three main types:

• Pre-receptor insulin resistance – insulin molecules cannot bind to the receptor due to abnormalities in insulin structure or quantity (e.g., genetic mutations).

• Receptor insulin resistance – insulin binds to the receptor, but the receptor does not transmit the signal further.

• Post-receptor insulin resistance – both insulin and the receptor work, but the signaling pathways inside the cell are impaired.

The type of insulin resistance does not significantly affect treatment strategies. Therapy always focuses on improving tissue sensitivity to insulin, stabilizing blood glucose levels, and preventing metabolic complications.

Causes of Insulin Resistance

The causes include both genetic predispositions and environmental factors.

Genetic factors may involve mutations in genes related to glucose metabolism and insulin action, increasing the risk of developing insulin resistance.

Environmental factors include:

• Visceral obesity – excess fat around the abdomen triggers the release of pro-inflammatory cytokines that interfere with insulin signaling.

• Overeating, especially periodic binge eating, causes large insulin spikes and increased fat storage.

• Lack of physical activity – reduces muscles’ ability to efficiently use glucose, placing additional strain on the pancreas.

• Chronic stress – raises cortisol levels, which impairs insulin function.

• Hormonal disorders – such as PCOS or hypothyroidism, can contribute to insulin resistance.

• Chronic inflammation – may lead to insulin receptor dysfunction.

• Certain medications, such as glucocorticoids, can also worsen insulin sensitivity.

How to Check If You Have Insulin Resistance?

Insulin resistance is not classified as a separate disease. Therefore, there are no universal diagnostic criteria. Assessment is based on interpreting various biochemical and anthropometric parameters.

HOMA-IR
One of the most commonly used tools is the HOMA-IR (Homeostatic Model Assessment of Insulin Resistance). It is calculated based on fasting glucose and insulin levels. A result above 2.5 in the European population may indicate insulin resistance. However, the cut-off point may vary depending on age, sex, or ethnicity.

Oral Glucose Tolerance Test (OGTT)
Another key test is the OGTT, which involves measuring glucose and insulin levels at intervals after consuming a glucose solution. It helps assess both glucose and insulin responses.

Other diagnostic parameters:

• Lipid profile – high triglycerides and low HDL may suggest insulin resistance.

• Hemoglobin A1c (HbA1c) – reflects average blood glucose over the past 2–3 months.

• Anthropometric indicators, such as BMI and waist circumference. A waist circumference over 80 cm in women and 94 cm in men is one of the criteria for metabolic syndrome, which often coexists with insulin resistance.

A comprehensive diagnostic approach, including lab tests and risk factor evaluation, allows for early detection and preventive action.

How to Treat Insulin Resistance?

Treatment requires a multifaceted approach, including lifestyle changes, sometimes pharmacotherapy, and patient education. The goal is to improve insulin sensitivity, reduce the risk of type 2 diabetes, and enhance overall metabolic health.

Medications:

• Metformin is the most commonly used drug. It reduces hepatic glucose production and increases glucose uptake by skeletal muscles, lowering blood sugar and improving insulin sensitivity.

• GLP-1 receptor agonists (e.g., Ozempic) are increasingly discussed. These medications boost insulin secretion in response to glucose, delay gastric emptying, and reduce appetite – helping with weight loss and improved glycemia. However, they are not typically used for insulin resistance alone without type 2 diabetes or obesity.

First-line treatment usually involves lifestyle changes – healthy eating, weight loss, and regular physical activity. Medications are more often used as supportive therapy.

Supplements for Insulin Resistance

Supplementation can support treatment, improve insulin sensitivity, and reduce inflammation. However, supplements should not replace a healthy lifestyle or medical treatment and should be used under medical supervision, especially when combined with antidiabetic drugs.

Recommended supplements:

• Berberine – inhibits glucose production in the liver, improves insulin sensitivity, and works similarly to metformin.

• Vitamin D – deficiency may worsen insulin resistance and inflammation. Supplementation supports pancreatic function and insulin receptor activity.

• Magnesium – essential for glucose metabolism and insulin receptor function. Deficiency is common in people with insulin resistance.

• Omega-3 fatty acids – reduce inflammation and improve metabolic function, including insulin sensitivity.

Diet for Insulin Resistance

A proper diet is key to improving insulin sensitivity and maintaining stable blood glucose levels. Main dietary principles include:

• choosing low glycemic index (GI) foods,

• avoiding snacking between meals,

• eating meals regularly,

• balancing nutrients to slow glucose absorption.

It is recommended to eat 4–5 meals a day at regular intervals (every 3–4 hours) to maintain stable glucose and insulin levels. Avoiding snacking is important, as constant eating causes excessive insulin secretion.

Glycemic Index and Insulin Resistance

The glycemic index (GI) indicates how quickly a food raises blood glucose levels after consumption. Carbohydrate-rich foods are ranked based on how fast they increase blood sugar compared to pure glucose (GI = 100).

How GI works:
High-GI foods cause rapid blood glucose spikes, leading to strong insulin release. Low-GI foods lead to gradual glucose release, keeping blood sugar levels more stable.

GI categories:

• Low GI (≤55): slow and steady glucose rise.
  Examples: non-starchy vegetables (e.g., broccoli, zucchini), berries (e.g., strawberries, raspberries), whole grains, legumes (e.g., lentils, beans).

• Medium GI (56–69): moderate glucose rise.
  Examples: bananas, oats, basmati rice.

• High GI (≥70): rapid glucose rise.
  Examples: white bread, white rice, mashed potatoes, sweets, sugary drinks.

Why GI matters in insulin resistance:
With insulin resistance, the body responds poorly to insulin, slowing glucose removal from the blood. High-GI foods cause glucose and insulin spikes, while low-GI foods help maintain stable blood sugar and prevent excessive insulin release.

Insulin Resistance – Where to Begin?

Insulin resistance is a growing problem. Fortunately, it can often be managed effectively through appropriate diet and lifestyle. At first, dietary recommendations may seem difficult, but over time…

Insulin resistance – where to start?

Insulin resistance is an increasingly common condition. Fortunately, in many cases, an appropriate diet is enough to minimize its negative effects. At first, dietary recommendations may seem difficult to implement, but quite quickly they can become a natural part of your daily routine.

Start by:

• Limiting sugar and refined carbohydrates – eliminate sugary drinks, sweets, white bread, and highly processed foods.

• Eating regularly – consume 4–5 balanced meals a day at regular intervals to avoid glucose and insulin spikes.

• Choosing whole foods – opt for high-fiber foods with a low glycemic index: vegetables, whole grains, legumes, and healthy fats.

• Increasing physical activity – regular movement improves muscle sensitivity to insulin and helps with weight reduction.

• Taking care of sleep and stress levels – poor sleep quality and chronic stress can worsen insulin resistance.

By making conscious lifestyle changes, you not only improve insulin sensitivity but also reduce the risk of many chronic diseases such as type 2 diabetes, cardiovascular disease, and metabolic syndrome.