Type 2 Diabetes – Insulin Resistance and Beta Cell Dysfunction

What is Type 2 diabetes?

* Its genetic inheritance (infact genetic factors are more important than type 1 diabetes)

* Insulin resistance

* Partial insulin deficiency

* Age over 40 years

* No autoimmunity

* Development of Hyperosmolar nonketotic coma instead of ketoacidosis

* Insulin treatment sometimes

* Often obese

What causes Type 2 diabetes?

The main factor in type 2 diabetes is insulin resistance. This is caused by genetic predisposition, lifestyle factors, obesity etc. Once there will be insulin resistance (cells are not responsive to insulin actions), beta cells produce more insulin to maintain normal glucose levels and to overcome insulin resistance. This leads to beta cell hyperplasia (number of beta cells are increased).

This will go on for a while and at one time beta cells are unable to produce enough insulin leading to ‘Glucose intolerance’. Further down the road, beta cells will fail to cope up with insulin resistance and insulin secretion will fall. This produces frank diabetes status.

Factors that causes type 2 diabetes?

Insulin resistance :

Insulin resistance is defined as the resistance to the effects of the insulin on glucose uptake, metabolism and storage. Decreased uptake of glucose in to muscle and adipose tissue is seen and liver glucose production is not suppressed. End result is increased glucose levels in blood.

There are many genetic defects of insulin receptors in the type 2 diabetics which are responsible for the development of insulin resistance.

Obesity and Insulin resistance :

Abdominal obesity (central obesity) is implicated in insulin resistance than peripheral obesity. Free fatty acids are more in blood in obese people and these levels are inversely related to the insulin sensitivity. The more FFAs in plasma, less is insulin sensitivity and more will be the insulin resistance.

Fat stores releases some hormone like substances called adipokines. Examples are leptin, adiponectin, resistin etc. Their altered secretions (either decrease or increase) implicated in insulin resistance. For example, leptin acts on brain to reduce food intake and induce satiety. Leptin deficient animals exhibits insulin resistance and reversed by administration of leptin.

Beta cell dysfunction :

As described above, beta cells slowly exhausted because of chronic hyperglycemia and insulin resistance though they produce more insulin in initial stages. Several mechanisms are proposed for these beta cell dysfunction like – toxicity of free fatty acids in plasma or chronic hyperglycemia. There will be decrease in beta cell mass, islet cell degeneration and deposition of pink color protein called amyloid.

Genetic factors :

Genetic factors are important than type 1 diabetes with 50 – 90% of concordance rate between identical twins. First degree relatives with type 2 diabetes, risk of developing disease is 20 – 40%. Though the genetic factors plays much role, there is no role for autoimmunity like type 1 diabetes.

[tags]diabetes, diabetic, beta cell dysfunction, insulin resistance, type 2 diabetes[/tags]