What causes insulin resistance?

Dr. Jack Merendino, MD
Endocrinology Diabetes & Metabolism
The cause of insulin resistance has been one of the most pressing questions in diabetes research. There’s one clear link: being overweight or obese. And there’s an even clearer culprit: a large belly. Actually, a specific type of belly fat, called visceral or intra-abdominal fat, is to blame. This is fat in and around the liver and other organs inside the abdomen, and it differs from subcutaneous fat -- fat under the skin. Liposuction can’t reduce visceral fat because the procedure removes only subcutaneous fat. Subcutaneous fat does not seem to cause insulin resistance or the other problems that are part of the metabolic syndrome.

Why is visceral fat so toxic? It appears that visceral fat cells manufacture chemicals that prevent other cells from responding to insulin as they should. These chemicals also trigger inflammation.  Inflammation is one of the body’s ways of responding to injury, but it can also cause injury to tissues and promotes the development of atherosclerosis in blood vessels. 

The Best Life Guide to Managing Diabetes and Pre-Diabetes

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The Best Life Guide to Managing Diabetes and Pre-Diabetes

Bob Greene has helped millions of Americans become fit and healthy with his life-changing Best Life plan. Now, for the first time, Oprah's trusted expert on diet and fitness teams up with a leading...
Emilia Klapp
Nutrition & Dietetics
A number of malfunctions in the body may prevent insulin from doing its job of enabling glucose to enter the cells for fuel. The pancreas might produce insulin but in an insufficient amount to reach every cell, for example. Other malfunctions include:
  • The pancreas secretes defective insulin, which cannot open the
         20,000 or so insulin receptors on healthy muscle, fat, and liver
  • The cell membranes do not have enough insulin receptors to interact
         with the insulin. The cell membranes in an overweight person
         have only 5,000 receptors.
  • The insulin receptors do not work properly.
  • There are not enough glucose transporters attached to the insulin to
         carry glucose into the cells.

Obesity contributes to insulin resistance and negatively affects the body’s ability to use insulin properly. 

Dr. Mehmet Oz, MD
Cardiology (Cardiovascular Disease)
Insulin resistance means your body cannot respond the insulin produced by your pancreas. Watch the video to learn more about insulin resistance.

The cause of insulin resistance is complex and is still a very active area of research. It appears that a certain type of fat tissue, fat that is contained in the abdomen (also called visceral adipose tissue), produces certain hormones and other substances that together cause insulin resistance. This was a major surprise in medicine when it was discovered only 10 or 15 years ago. Prior to that, fat tissue was considered to be "metabolically inert", which means that it was just a storage tissue and didn't affect metabolism. This was very far from the truth, and visceral fat is now considered to be very active and complex metabolically.

It produces a host of hormones (for example leptin, ghrelin and adiponectin) and other factors (cytokines) that have major influences on metabolism. The discovery that insulin resistance was the central "lesion" in type 2 diabetes led to a whole area of research that resulted in linking type 2 diabetes to high blood pressure, truncal or abdominal obesity, abnormal blood lipids (elevated triglycerides and low HDL cholesterol), and high waist to hip ratio (the "apple" body type).

It was originally described by Gerald Reaven, MD a professor of medicine at Stanford University, who named it Syndrome X to underscore how little-understood it was and highlight that it was more than just elevated blood sugars that caused disease. He wrote a book for the general public on this called Syndrome X, published by Simon and Shuster in 2000. Syndrome X is now also called metabolic syndrome and prediabetes, and the majority of people with type 2 diabetes have some or all of its features.

Continue Learning about Diabetes Type 2

Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.