Incretin: Difference between revisions

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'''Incretin''' is a group of metabolic hormones that stimulate a decrease in blood glucose levels. Incretins are released after eating and augment the secretion of [[insulin]] released from pancreatic [[beta cells]] of the [[Islets of Langerhans]] by a blood glucose-dependent mechanism.  
{{DISPLAYTITLE:Incretin}}
 
== Overview ==
[[File:Incretins_and_DPP_4_inhibitors.svg|thumb|right|Diagram illustrating the role of incretins and DPP-4 inhibitors.]]
Incretins are a group of metabolic hormones that stimulate a decrease in blood glucose levels. They are released after eating and augment the secretion of insulin released from the pancreatic beta cells of the [[islets of Langerhans]]. The two main incretins in humans are [[glucagon-like peptide-1]] (GLP-1) and [[gastric inhibitory polypeptide]] (GIP), also known as glucose-dependent insulinotropic polypeptide.


== Function ==
== Function ==
Incretins play a crucial role in the regulation of insulin secretion. They enhance the insulin response to oral glucose intake, a phenomenon known as the "incretin effect." This effect is responsible for the greater insulin response to oral glucose compared to intravenous glucose. Incretins also slow gastric emptying, inhibit glucagon release, and promote satiety, thereby contributing to the regulation of postprandial glucose levels.


Incretins are a group of [[gastrointestinal]] hormones that cause an increase in the amount of insulin released from the beta cells of the pancreas after eating, even before blood glucose levels become elevated. They also slow the rate of absorption of nutrients into the blood stream by reducing gastric emptying and may directly reduce food intake. Together, these effects lead to a decrease in blood glucose levels, avoiding the drastic peaks in blood glucose that would otherwise result from the absorption of nutrients.
== Mechanism of Action ==
 
Incretins exert their effects by binding to specific receptors on the surface of pancreatic beta cells. GLP-1 binds to the GLP-1 receptor, while GIP binds to the GIP receptor. This binding activates intracellular signaling pathways that lead to increased insulin secretion. Additionally, GLP-1 has been shown to have protective effects on beta cells, promoting their survival and proliferation.
== Types of Incretins ==
 
There are two main types of incretins: [[Glucagon-like peptide-1]] (GLP-1) and [[Gastric inhibitory polypeptide]] (GIP). Both hormones are rapidly inactivated by the enzyme [[Dipeptidyl peptidase-4]] (DPP-4).
 
=== Glucagon-like peptide-1 ===


GLP-1 is a hormone that is secreted from L cells, which are a type of enteroendocrine cell located in the ileum and colon. It is secreted in response to food intake and has several effects that result in lower blood glucose levels.
== Degradation ==
Incretins are rapidly degraded by the enzyme [[dipeptidyl peptidase-4]] (DPP-4). This enzyme cleaves the incretins, rendering them inactive. The short half-life of incretins in the bloodstream is due to this rapid degradation, which limits their physiological effects.


=== Gastric inhibitory polypeptide ===
== Clinical Significance ==
The incretin system is a target for the treatment of [[type 2 diabetes mellitus]]. DPP-4 inhibitors, also known as gliptins, are a class of oral hypoglycemics that prolong the action of incretins by inhibiting their degradation. This results in increased insulin secretion and decreased glucagon levels, leading to improved glycemic control.


GIP is a hormone that is secreted from K cells, which are a type of enteroendocrine cell located in the duodenum and jejunum. It is also secreted in response to food intake and has several effects that result in lower blood glucose levels.
== Related Pages ==
 
== Clinical significance ==
 
Incretin-based therapies, such as GLP-1 receptor agonists and DPP-4 inhibitors, are a type of treatment for [[Type 2 diabetes]]. They work by mimicking the effects of the body's own incretins or by preventing the body from breaking down its own incretins.
 
== See also ==
 
* [[Insulin]]
* [[Glucagon-like peptide-1]]
* [[Glucagon-like peptide-1]]
* [[Gastric inhibitory polypeptide]]
* [[Gastric inhibitory polypeptide]]
* [[Dipeptidyl peptidase-4]]
* [[Dipeptidyl peptidase-4]]
* [[Type 2 diabetes]]
* [[Type 2 diabetes mellitus]]
* [[Insulin]]


[[Category:Endocrinology]]
[[Category:Endocrinology]]
[[Category:Diabetes]]
[[Category:Diabetes]]
[[Category:Hormones]]
{{stub}}

Latest revision as of 05:45, 16 February 2025


Overview[edit]

Diagram illustrating the role of incretins and DPP-4 inhibitors.

Incretins are a group of metabolic hormones that stimulate a decrease in blood glucose levels. They are released after eating and augment the secretion of insulin released from the pancreatic beta cells of the islets of Langerhans. The two main incretins in humans are glucagon-like peptide-1 (GLP-1) and gastric inhibitory polypeptide (GIP), also known as glucose-dependent insulinotropic polypeptide.

Function[edit]

Incretins play a crucial role in the regulation of insulin secretion. They enhance the insulin response to oral glucose intake, a phenomenon known as the "incretin effect." This effect is responsible for the greater insulin response to oral glucose compared to intravenous glucose. Incretins also slow gastric emptying, inhibit glucagon release, and promote satiety, thereby contributing to the regulation of postprandial glucose levels.

Mechanism of Action[edit]

Incretins exert their effects by binding to specific receptors on the surface of pancreatic beta cells. GLP-1 binds to the GLP-1 receptor, while GIP binds to the GIP receptor. This binding activates intracellular signaling pathways that lead to increased insulin secretion. Additionally, GLP-1 has been shown to have protective effects on beta cells, promoting their survival and proliferation.

Degradation[edit]

Incretins are rapidly degraded by the enzyme dipeptidyl peptidase-4 (DPP-4). This enzyme cleaves the incretins, rendering them inactive. The short half-life of incretins in the bloodstream is due to this rapid degradation, which limits their physiological effects.

Clinical Significance[edit]

The incretin system is a target for the treatment of type 2 diabetes mellitus. DPP-4 inhibitors, also known as gliptins, are a class of oral hypoglycemics that prolong the action of incretins by inhibiting their degradation. This results in increased insulin secretion and decreased glucagon levels, leading to improved glycemic control.

Related Pages[edit]