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Diabetes Basics

Diabetes is a condition that we all understand a little about, or at least we think we do.... but a lot of us get stuck quite quickly once we get past the basics. These pages aim to demystify the physiology of healthy blood-glucose regulation. We'll then move onto when regulation goes wrong (eg. diabetes). 

A beginners guide to how insulin and glucagon help the body use, store and regulate glucose. 

Don't know your type one from your type two? Well look no further!

Healthy Glucose Regulation

It's helpful to know what glucose regulation looks like when it's going well, before we get to stuck into when it goes wrong. In this section we'll look at glucose regulation when the endocrine system is working as expected. We'll investigate the various roles insulin plays in managing the glucose we absorb from our diets, as well as the role of Glucagon when glucose supplies are running low. 

If you find visuals helpful then you can watch my animated video here.

glucs regulatin

To Much of a good thing: While the presence of at least some glucose in the blood is essential, high concentrations become toxic! 

Insulin- the hormone in charge when glucose levels are high!!

 

Secretion 

Insulin is secreted into the blood by specialist cells in the pancreas. Secretion is stimulated by the presence of glucose in the blood. Higher blood sugars lead to higher blood insulin levels. 

Role one: 'Unlocking' cells for glucose

Glucose must pass into a cell before it can be broken down for energy, but it can't pass through a cell membrane without help. Insulin must first interact with the cell membrane, making it permeable to glucose. It can be helpful to think of insulin as a key, unlocking the cell to allow glucose to enter. Without insulin glucose would remain trapped in the blood, depriving the body of a source of energy! 

Role two: regulating the storage of glucose

Excess glucose is taken out of the blood and stored away for later use. Most glucose is stored in the liver, although some storage in skeletal muscle and fat cells also occurs. Insulin is once again the hormone driving this process. Insulin stimulates the liver to absorb glucose from the blood, converting it into a slightly modified form, called glycogen, for storage. 

Role three: Regulation of the hormone glucagon.......

Insulin acts as a 'key' unlocking the cells so glucose can enter.

Insulin promotes the uptake of glucose into the liver and muscles for storage. For storage, glucose is converted to glycogen.

Why Regulate?

Cells need a constant supply of energy 

For the body's cells to function they need a steady fuel supply. Glucose is a major source of energy for cellular metabolism (activity). However, most cells cannot store glucose, therefore the body must provide them with a steady supply via the blood. There must always be at least some glucose present in the blood. 

Too much of a good thing

Low blood glucose levels can be very dangerous, but excessively high glucose levels can also be hazardous too! Hyperglycaemia (high blood sugar) are associated with many short and long-term health consequences, including increased risks of stroke and heart disease. It is therefore essential that excess glucose is taken out of the blood before it can cause harm.

An inconsistent supply

While the body's need for glucose for energy is constant, the supply is not! All of us go through periods of fasting (eg. when we sleep), and during these periods new glucose is not being absorbed into the body from our diets. It is therefore essential that the body can store excess blood glucose when levels are high, and take glucose out of storage and back into the blood when glucose levels are low. 

In order to conduct effective and healthy glucose regulation the body must therefore be able to do three things;

  1. Provide cells with a constant supply of glucose via the bloodstream.

  2. Remove excess glucose from the blood (storing it away for later use).

  3. Take glucose out of storage and back into the bloodstream when blood sugar levels are low.

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Glucose is one of the bodies primary sources of energy. It is broken down inside cells to produce 'ATP', which can then bu used to power cellular metabolism.

Glucagon: what you need when your blood runs low on glucose!

 

Secretion

Glucagon is also secreted by the pancreas. The presence of insulin in the blood suppresses its release, so when insulin levels are high, eg. after a meal, Glucagon levels will be low. But if blood-insulin levels begin to drop (for example, when we fast), more glucagon will be able to enter the blood.

Ensuring a steady fuel supply

One of Glucagon's primary roles is to release the body's supplies of stored glucose in times of need. When Glucagon interacts with the liver and muscle cells it stimulates them to convert some of their Glycogen back to glucose, ensuring the body's cells still have a source of energy. 

Not forgetting fat cells!

Glucagon will also interact with fat cells, causing them to release amino acids into the blood, which the liver can turn into ketones. Ketones are another important source of energy for cellular metabolism. They can be taken into cells and broken down for energy. However, they come with a catch... Ketones are acidic and have the potential to reduce blood pH to dangerously low levels (see Ketoacidosis for more details). 

Working together!

Hopefully now the basics of regulation are starting to make some sense! Insulin and Glucagon together keep glucose levels within a healthy range ensuring the body never has to go with out a fuel supply.  

Blood glucose levels increasing (after a meal) stimulates the release of Insulin from the pancreas, which in turn leads to more glucose being taken into cells & broken down for energy, and more glucose being taken into the liver the muscles (as glycogen) for storage. The net result is a reduction in blood glucose levels.