Insulin Resistance: What It Is, Symptoms, Diagnosis & Treatment

What is Insulin Resistance? Insulin resistance refers to a condition where biological processes that should normally occur in response to insulin hormone levels, which may be normal or elevated, do not take place properly. The liver, muscle tissue, and adipose tissue are the primary organs affected by insulin. As insulin resistance develops, the pancreas may produce more insulin in an attempt to overcome the resistance. This leads to a condition known as hyperinsulinemia, where insulin levels in the blood are significantly higher than normal. Over time, insulin resistance can progress to metabolic syndrome or type 2 diabetes (diabetes mellitus) and other clinical conditions. It is estimated that approximately 9% of the global population is affected by type 2 diabetes, which can develop as a result of insulin resistance. Other conditions related to insulin resistance include obesity, cardiovascular diseases (heart and blood vessel diseases), non-alcoholic fatty liver disease, metabolic syndrome, and polycystic ovary syndrome (PCOS).

Causes of Insulin Resistance

Various metabolic changes and conditions can play a role in the development of insulin resistance. One of the primary factors is an increase in the amount of fat-like substances in the bloodstream. Free fatty acids are substances that can disrupt the body's response to insulin. A high-calorie diet and excessive amounts of fat tissue in the body can increase the amount of free fatty acids in the bloodstream. Thus, imbalanced and excessive nutrition, leading to obesity, is an example of conditions related to insulin resistance.

The causes of insulin resistance can be classified into two categories: acquired and inherited (genetic). Acquired causes of insulin resistance include several conditions that can lead to the development of insulin resistance over time:

• Functioning and excessive fat tissue
• Aging
• Lack of physical activity
• Imbalances in consumed nutrients
• Use of various medications
• Increased salt intake through diet

What Are the Symptoms of Insulin Resistance?

People with insulin resistance can live for years without being diagnosed due to the lack of noticeable symptoms. This happens because insulin resistance can develop without leading to any distinct signs. However, there are several symptoms associated with insulin resistance that are considered risky:

• Waist circumference over 102 cm in men and over 88 cm in women
• Blood pressure of 130/80 or higher
• Fasting blood sugar levels above 100 mg/dL
• Fasting triglyceride levels above 150 mg/dL

The development of insulin resistance can set the stage for the onset of diabetes. After diabetes develops, various additional symptoms may appear:

• Excessive hunger and thirst
• Persistent hunger after meals
• Increased frequency of urination
• Unusual fatigue
• Increased susceptibility to infections and frequent illnesses

Another sign of insulin resistance is acanthosis nigricans. This condition refers to the development of velvety, brownish skin changes typically found around the neck, armpits, and groin.

How is Insulin Resistance Calculated?

While there are several methods to calculate insulin resistance, the HOMA (Homeostasis Model Assessment) method is the most commonly used. This test not only measures insulin resistance but also provides information about the function of insulin-producing cells in the pancreas. The HOMA method uses two parameters: the fasting blood sugar level and the insulin level. These two values are multiplied together, and the result is divided by 405 to calculate the HOMA score.

If the HOMA score is above 2.5, it indicates the presence of insulin resistance.

However, it is not necessary to check the HOMA value for every patient. The best parameter to indicate insulin resistance in clinical practice is waist circumference measurement.

How is Insulin Resistance Diagnosed?

Diagnosis can be made through the patient's symptoms, physical examination findings, and a simple waist circumference measurement. In some cases, additional tests may be required to assess the risk of diabetes.

Tests that may be requested include the fasting plasma glucose test, oral glucose tolerance test, and HbA1c test, which measures the average blood sugar levels over the past 2-3 months.

The fasting plasma glucose test determines the blood sugar level after fasting for at least 8 hours. If high levels are detected, the test may need to be repeated after a few days for confirmation.

According to the test results, values below 100 mg/dL per deciliter are considered normal. Blood sugar levels between 100 and 125 mg/dL may indicate prediabetes (the stage before diabetes). Values of 126 mg/dL or higher are diagnostic of diabetes.

Another test, the oral glucose tolerance test, involves drinking a sugary liquid, and measuring blood sugar levels two hours later. Values below 140 mg/dL are considered normal, values between 140 and 199 mg/dL suggest prediabetes, and blood sugar levels above 200 mg/dL are considered diabetes.

How is Insulin Resistance Treated?

The first and most important step in treating insulin resistance involves lifestyle changes, which include a variety of strategies. These include classifying the calorie intake from daily meals and avoiding foods with high glycemic content. Increasing physical activity can enhance energy usage in the body and help restore the muscles' sensitivity to insulin. Regular physical activity can also help reduce abdominal fat.

Tobacco use is one of the harmful habits that can contribute to insulin resistance. Therefore, quitting this habit can be an important step in breaking insulin resistance.

Eating a balanced diet consisting of whole, unprocessed foods is another essential approach for combating insulin resistance. Avoiding foods with artificial sweeteners and limiting daily sugar intake are important to reduce insulin resistance.

In addition to these approaches, consuming omega-3 fatty acids, reducing stress, and ensuring a quality sleep routine are lifestyle changes that can also help improve insulin resistance.

Proper and planned lifestyle changes require patient education. Professional dietitians can provide advice on limiting salt, fat, and total daily calorie intake. With proper dietary planning, helping a person lose approximately 7% of their body weight can reduce the risk of developing type 2 diabetes by about 60%.

If necessary, or when lifestyle changes are found to be ineffective in breaking insulin resistance or if the risk of diabetes is high, the doctor may prescribe insulin-sensitizing medications to assist in managing the condition.