Insulin resistance: what it is and why it occurs

The term "insulin resistance" appears in test reports and in articles about diabetes. Let us calmly explain what this condition is, why it occurs, and in which cases a conversation with an endocrinologist is needed.

What insulin resistance is

Insulin is a hormone of the pancreas that helps glucose from the blood enter the cells of muscles, adipose tissue, and the liver. In insulin resistance, cells do not respond to it as they should: glucose stays in the blood, and more of the hormone is produced than usual. Insulin resistance is an impairment of the metabolic response to the hormone in which its concentration in plasma rises relative to the existing glucose level. Insulin resistance syndrome (syndrome X) is described as a combination of resistance to insulin-dependent glucose uptake, obesity, dyslipidemia, impaired glucose tolerance, and type 2 diabetes.

Why insulin resistance develops: causes

The mechanism has not been fully studied. The impairment forms at the level of receptors, glucose transport (fewer GLUT4 molecules), or signal transmission inside the cell — the post-receptor level is considered the main one. More often the condition develops in people with excess body weight and a tendency to arterial hypertension. The likelihood is increased by excess body weight and a large waist circumference, age 35 years and older, a family history of diabetes, smoking and tobacco smoke, low physical activity, past gestational diabetes or the birth of a child weighing 4 kg or more, polycystic ovary syndrome, Cushing syndrome, acromegaly, sleep apnea, previous viral diseases, long-term use of glucocorticoids, some antipsychotics, and medications for treating HIV. Age, heredity, and ethnic origin cannot be changed.

Insulin resistance and diabetes: what the link is

The link is direct, but the concepts are not equivalent. While the beta cells of the pancreas cope, they release more insulin, and glucose remains normal — relative hyperinsulinemia. When the beta cell reserve is depleted, there is not enough hormone to overcome the resistance, and blood glucose rises. The intermediate step is prediabetes: glucose is above normal but not high enough for a diagnosis of type 2 diabetes, in which insulin works incorrectly or there is not enough of it. Not every person with prediabetes develops diabetes, but the probability over 5–10 years is high.

How it manifests and what to pay attention to

People with insulin resistance and prediabetes usually have no symptoms; sometimes complaints similar to manifestations of diabetes appear. Insulin resistance is associated with high blood pressure, metabolic syndrome, changes in the vessel walls, nonalcoholic fatty liver disease, and unhealthy cholesterol and triglyceride levels.

How insulin resistance is detected

There is no separate test that determines insulin resistance in everyday practice: this indicator is measured mainly in research studies. In practice, risk is assessed and tests for prediabetes are ordered: A1C shows average glucose over the last 3 months, the prediabetes range is 5.7–6.4%; fasting plasma glucose is above normal but below the diagnostic threshold for diabetes. The calculated HOMA-IR index is also used: in adults aged 20–60 years without diabetes, the reference range is 0–2.7. The diagnosis is confirmed by repeated measurement of glycemia.

When to consult an endocrinologist

The reason is not how you feel but risk factors. Testing is discussed if:

• you are 35 years old or older;
• there is excess body weight or obesity together with other risk factors;
• close relatives have diabetes, there was gestational diabetes, or a child was born weighing 4 kg or more;
• polycystic ovary syndrome, sleep apnea, or arterial hypertension has been diagnosed;
• a child or adolescent with excess body weight has reached 10 years of age or puberty.

If risk factors are present but prediabetes is not found, testing is repeated at least once every 3 years; if prediabetes is detected, testing for type 2 diabetes is done every year.

Insulin resistance by itself is not a reason to call an ambulance; 103/112 — for signs of stroke or heart attack.

This material is for reference and does not replace a doctor's consultation: the decision on testing is made by a specialist.

This content is for reference and does not replace a doctor's consultation. Medical disclaimer