Endogenous insulin is a hormone secreted by pancreatic beta cells (ß), located in the islets of Langerhans. The islets of Langerhans are clusters of four cell types, (alpha, beta, delta, and F) surrounded by pancreatic ancini. Drag your cursor over the map to identify cells and their related products.
The
type of pancreatic islet cell that is responsible for secreting insulin is the alpha
cell.
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Insulin has the following important
effects on body tissues: |
|
| ⇑ | Anabolism – the metabolic process that constructs complex molecules from simple ones. |
| ⇓ | Glycogenolysis - the conversion of glycogen stored in the liver or muscle cells into glucose |
| ⇓ | Gluconeogenesis - the formation of glucose from non-carbohydrate sources such as amino acids during fasting and starvation. |
| ⇑ | Protein synthesis - protein formation from amino acids by stimulating the entry of amino acids into cells |
| ⇑ | Lipogenesis - the synthesis and storage of fat |
The term "endogenous" insulin refers to insulin produced by beta cells in the individual's pancreas. "Exogenous" insulin is a term used to describe pharmaceutical insulin, usually biosynthetic human insulin or purified porcine insulin.
Counter-regulatory hormones are hormones that block the effects of insulin, thus increasing blood glucose. Important counter-regulatory hormones include: glucagon, epinephrine, norepinephrine, growth hormone, and cortisol. Blood glucose management in diabetes must account for the release of one or more of these counter-regulatory hormones throughout the day.
Insulin is essential for normal carbohydrate, protein and fat metabolism. People with type 1 diabetes (T1D) produce little to no endogenous insulin and therefore require exogenous insulin for survival. While people with type 2 diabetes (T2D) produce endogenous insulin, over time many experience a progressive loss of beta cell function and may require supplemental exogenous insulin for adequate blood glucose control. Times of stress or illness can substantially increase the need for insulin. This is why the designation "T2D" has replaced the former term "non-insulin dependent diabetes mellitus."
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