Insulin Resistance: Causes, Symptoms, and Treatment

Tzvi Doron, DO, is a diplomate of the American Board of Obesity Medicine and board-certified in Family Medicine.

In short, insulin resistance is exactly what it sounds like - it’s a condition in which your body becomes resistant (or less sensitive) to the hormone insulin. Fully understanding what this means and how it can affect your body, though, depends on an understanding of what insulin even is, to begin with. Once we’ve covered that, we can get back to insulin resistance.

Insulin is a hormone in the body that is produced by the pancreas, an organ that sits behind your stomach. The pancreas has specialized regions called the islets of Langerhans, and these are where hormone-secreting cells lie. Specifically, there are cells called beta cells in the islets of Langerhans, and the beta cells are the ones that make insulin.

Insulin is one of the main hormones in the body that helps regulate blood sugar levels (also called blood glucose levels). Usually, blood sugar levels go up after you eat food that has sugars or carbohydrates. In response to elevated blood sugar levels, insulin is released from the beta cells into the bloodstream. Insulin then lowers blood sugar levels by doing the following:

It helps fat cells take up glucose, which can be stored as triglycerides (a type of fat)

It helps liver cells take up glucose, which can be stored as glycogen (a chain of sugars)

It helps muscle cells take up glucose, which can be used for energy or stored as glycogen to be used for energy later

Besides T2DM, insulin resistance is often talked about in combination with the metabolic syndrome. The term “metabolic syndrome” refers to a group of conditions that are each a risk factor for developing T2DM and/or cardiovascular disease (heart disease and blood vessel disease). Metabolic syndrome is also sometimes referred to as “syndrome X.” Components of the metabolic syndrome include:

Excess belly fat or an enlarged waistline (central obesity)

Perhaps one of the most frustrating things of all is that researchers don’t entirely know what causes insulin resistance. While we have been able to identify specific things that put you at increased risk, the actual mechanism by which insulin resistance manifests has remained elusive. That being said, the most significant contributors are:

Sedentary lifestyle: Not getting enough physical activity each day is linked to insulin resistance.

There are also non-obesity related causes of insulin resistance ( UpToDate, 2018 ).

Certain medications: Medications that have been implicated in insulin resistance include steroids (e.g., prednisone), some antipsychotics, some HIV medications, and oral contraceptives.

Certain medical conditions: Medical conditions that affect hormones can lead to insulin resistance, including Cushing’s syndrome (high levels of cortisol) and acromegaly (high levels of growth hormone).

Pregnancy: Hormones associated with pregnancy, including placental lactogen, can play a role in developing insulin resistance. This may lead to gestational diabetes in susceptible women.

Other issues with fat: Conditions of abnormal distribution of fat (lipodystrophy) or fat loss (lipoatrophy) can cause severe insulin resistance.

Type A insulin resistance: This is due to genetic conditions that cause a problem with the insulin-signaling pathway.

Type B insulin resistance: This is due to antibodies that block insulin receptors.