Role of multiple organs and tissues in type 2 diabetes

Type 2 diabetes is increasingly seen as a disease in which multiple organs and tissues in the body play a role in causing high blood glucose. In fact, nowadays when researchers consider type 2 diabetes, they think of the “ominous octet” or organs and tissues that work together to contribute to elevated blood glucose. This octet includes1:

  • Muscle
  • Fat cells
  • Liver
  • Beta cells in the pancreas
  • Alpha cells in the pancreas
  • Intestine
  • Kidney
  • Brain

Muscle tissue. Muscle tissue throughout the body contribute to elevated blood glucose by becoming resistant to insulin and unable to take up glucose for cellular energy needs.

Fat cells. Fat cells in people with type 2 diabetes exhibit increased breakdown of fats and other lipids that contributes insulin resistance and increases fat deposits throughout the body.

Liver. In type 2 diabetes, the liver—a major site of glucose storage—attempts to compensate for the decreased ability of the body to use glucose and increases glucose production.

Pancreas (beta and alpha cells). Both alpha cells and beta cells in the pancreas play a central role in type 2 diabetes. Beta cells lose the ability to produce insulin, while alpha cells increase production of glucagon, the hormone that plays a role in transforming glycogen stored in the liver and muscles back into glucose. Additionally, beta cells also produce the hormone amylin, which controls how quickly glucose is released into the blood stream after eating.

Intestine. Gastrointestinal tissues in the intestine become deficient in producing the hormones called incretins and resistant to its effects. Incretins stimulate the body to produce insulin after eating and also slow emptying of the stomach, which promotes the feeling of fullness and delays the release of glucose into the blood stream.

Kidney. The kidney increases glucose reabsorption, resulting in damage to the organ that ultimately keeps it from removing glucose from the bloodstream.

Brain. The brain plays a pivotal role in type 2 diabetes through impaired appetite regulation. Insulin typically acts as a appetite suppressant. However, the brains of individuals who are obese exhibit resistance to insulin. This resistance promotes increased food intake, which, in a viscous cycle, contributes to further obesity and exacerbates diabetes.

A closer look at the anatomy of the pancreas

As the site of two of the eight tissues/organs that contribute to the disease process involved in type 2 diabetes, the pancreas is of central importance. The organ is located behind the stomach and has two functions. As part of the endocrine system, it produces hormones including insulin, which it releases directly into the bloodstream. It also produces a range of digestive enzymes, chemicals that play a role in the breakdown and absorption of nutrients in the small intestine. In Western medicine, the pancreas was first described by the Greeks. The word pancreas comes from the Greek words pan for all and kreas for flesh. We think that these early scientists gave the organ this name because of its consistent fleshy texture.2

The pancreas makes up an important part of the endocrine system (the system of glands in the body that produce and release hormones and other chemicals directly into the bloodstream). The pancreatic cells that produce hormones are found in structures called islets of Langerhans. In most individuals, the pancreas contains about 1 million islets of Langerhans, which vary in size and each contain different cells that produce different hormones.2

A little history…

In case you’re wondering, Langerhans cells were named after a German physician and scientist named Paul Langerhans, who lived in the late 1880s and discovered the cells when he was a student at age 21. At the time, he mistakenly thought the cells were part of the nervous system.

In the pancreas, beta cells are located at the core of the islet and are the most common type of cell, making up about 70% of the islet. These are the cells that produce the hormone insulin. The core of beta cells in the islet is surrounded by alpha cells, which produce the hormone glucagon, which has an effect opposite of that of insulin, to raise blood glucose levels. Islets contain smaller numbers of two other cell types, delta cells and PP (pancreatic polypeptide) cells. Delta cells produce the hormone somatostatin, which has various functions including cell growth. PP cells regulate pancreatic secretions.2

Written by: Jonathan Simmons | Last reviewed: May 2014.
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