Insulin Resistance

All the information about the abnormal cellular response to insulin that leads to impaired absorption of blood glucose.

Symptoms and Causes

Insulin resistance is a metabolic disorder in which the body’s cells—mainly those in the muscles, liver, and adipose tissue—respond ineffectively to insulin, hindering glucose uptake into the cells and leading to hyperglycemia compensated by hyperinsulinemia. Although it is not the same as prediabetes, it represents a significant risk factor for developing it, along with type 2 diabetes and other metabolic diseases.

When insulin resistance begins to appear, the pancreas compensates by producing a larger amount of insulin, the hormone responsible for facilitating glucose entry into cells. However, over time, body tissues become increasingly less permeable, so even when insulin levels in the blood rise, glucose uptake remains minimal.

Although often confused, insulin resistance is not the same as prediabetes, which occurs when blood sugar levels are higher than normal but not high enough to be classified as diabetes. Even so, insulin resistance is a risk factor for developing prediabetes and diabetes in the future.

Detecting insulin resistance is not easy, as it is largely asymptomatic in its early stages. For this reason, routine blood tests are recommended for patients at higher risk of developing the condition, since early diagnosis is essential to prevent complications.

Symptoms

The symptoms of insulin resistance are usually nonspecific and, in many cases, do not appear until advanced stages:

Persistent fatigue and tiredness.
Difficulty losing weight, especially in the abdominal area.
Increased appetite.
Dark patches in skin folds (acanthosis nigricans), thickened skin on the neck, armpits, or groin.
High blood pressure, dyslipidemia, and abnormal glucose test results.
In women: menstrual irregularities, polycystic ovary syndrome.

Causes

The causes of insulin resistance are not fully understood, although both genetic predisposition and lifestyle factors play a role in its development.

Risk Factors

Factors that increase the risk of developing insulin resistance include:

Being over 45 years of age.
Having a family history of insulin resistance, prediabetes, or type 2 diabetes.
Having had gestationaldiabetes.
Sedentary lifestyle.
Obesity.
Diet high in refined sugars and carbohydrates.
High blood pressure.
High cholesterol levels.
Polycystic ovary syndrome.
Stroke.
Cushing’s syndrome: elevated cortisol levels, the hormone responsible for keeping the body alert in stressful situations.
Acromegaly: excessive production of growth hormone.
Sleep apnea.
Stress.
Smoking.
Certain medications: glucocorticoids, antipsychotics, steroids, HIV treatments.

Complications

Insulin resistance can lead to serious complications such as:

Type 2 diabetes.
Cardiovascular diseases.
Nonalcoholic fatty liver disease.
Along with obesity, certain types of cancer.

Prevention

The best way to prevent insulin resistance—though not always possible—is to adopt healthy lifestyle habits and have regular medical check-ups.

Which Doctor Treats Insulin Resistance?

Endocrinology and nutrition specialists are the professionals who diagnose and treat insulin resistance. Internal medicine specialists may also be involved.

Diagnosis

To diagnose insulin resistance, the following tests are usually performed:

Blood test: evaluates levels of glucose, sugar, and lipids such as cholesterol.
Glucose tolerance test: measures blood sugar levels before and after drinking a glucose solution.
HOMA-IR test (Homeostatic Model Assessment for Insulin Resistance): quantifies insulin resistance and evaluates the function of pancreatic beta cells, which synthesize insulin. The result is obtained by multiplying the fasting insulin level by the fasting glucose level and dividing by 22.5. A specialist must assess the results, as they vary from one laboratory to another, and other patient characteristics must also be considered for proper interpretation.