Diabetes Guide

Diabetes Mellitus as it is known medically is a condition that is characterised by a high or elevated level of blood sugar called glucose. It translates literally to mean ‘urine sweetened with honey’, which pertains to the sweet nature of the urine of diabetic patients. Currently it is estimated to affect over 120 million people worldwide and the number is rising rapidly.

Changes in Blood Glucose Levels

Glucose is a vital part of our diet and is found in many different types of food. When we eat, the carbohydrates we have in our diet are broken down by enzymes in our digestive system, to the smallest unit called, glucose. Once absorbed within our bodies, glucose is broken down to provide our cells with energy to grow and repair.

The enzymes that are involved in this process are called glycosylases and amylases and are produced within the α cells of the pancreas. This organ is located just behind the stomach on the left hand side of our bodies, containing 3 main types of cells, α cells, β cells and γ cells. Each of these cell types produces a different enzyme. The β cells produce insulin, whereas the γ cells are responsible for producing glucagon. Both of these enzymes are responsible for maintaining an adequate blood glucose level.

When we eat a meal, within 15 minutes our body absorbs the majority of the glucose through our intestines and into our blood. This causes our blood sugar levels to rise rapidly, prompting the pancreas to release insulin into our blood. The insulin then binds to specific receptors on our liver and muscle cells, telling them to take up and store glucose, and to stop producing glucose, in the case of the liver. This enables us to store glucose as glycogen, which can then be converted back to glucose in between meals.

As our blood sugar levels reach their peak after a meal, the amount of insulin within our blood begins to fall as the glucose is stored in our cells. The secretion of insulin then stops as the blood glucose levels begin to return to normal. In the time between meals, our blood sugar level can fall. In this case, glucagon is released from the pancreas, which causes the liver to release glucose for our body to use to produce energy. The concentration of glucose in our blood in between meals (3 hours after eating) is known as the fasting blood glucose concentration. Approximately 90% of this blood glucose is derived from stores of glycogen within the liver.

Although there are a number of types of diabetes, the two main forms are so called type 1 and type 2 diabetes. Each of these different types arise due to different types of problems within the body and as such have their own causes, symptoms and treatments.

Type 1 Diabetes

Type 1 diabetes or IDDM (insulin dependent diabetes mellitus) occurs due to the destruction or loss of function of the β cells within the pancreas. This stops the pancreas from releasing insulin into the blood when blood sugar levels rise. As such, after meals the body becomes unable to store any excess glucose we absorb into our blood and begins to release it in the urine. The resulting high glucose levels can then damage blood vessels and organs, especially the brain, eyes and kidneys. In severe cases the high glucose levels can cause unconsciousness and death.

Type 2 Diabetes

Type 2 diabetes or NIDDM (non-insulin dependent diabetes) is a problem that arises when the body loses its ability to respond to insulin. In other words, the pancreas can still release insulin but our cells no longer respond by absorbing and storing glucose. Just like type 1 diabetes, this causes problems following meals when our blood sugar levels rise. In both type 1 and type 2 diabetes, the body tries to release the excess glucose in the urine. This damages the kidney and can lead to kidney failure.

In this guide to diabetes, the different types of diabetes, causes, symptoms risk factors and treatments will be covered, along with a host of other useful information. If you are worried by any of the information you read and think you may have diabetes, please make an appointment with your GP who will be able to give you more information.

Diabetes & α cells

Alpha (α) cells are found within the region of your pancreas known as the Islets of Langerhans. The Islets of Langerhans contain the endocrine cells of your pancreas that release chemical messengers (hormones) into your blood stream in order to affect other organs of your body.  α cells are the endocrine cells responsible for releasing the hormone called glucagon which stimulates your liver (and muscle cells) to turn their stores of glycogen into glucose (sugar) and release it into your blood. In this way, the glucagon released by your α cells acts to increase your blood sugar levels. The glucagon released by your α cells can be thought of as an opposition to insulin (where insulin stimulates the cells of your body to absorb glucose form your blood and thereby reduces your blood sugar level). If you are diabetic then your body is either unable to respond to insulin or is unable to produce insulin so you will have a higher than normal blood sugar level. If the cells of your body signal to your brain that they are not getting enough sugar (either due to low blood sugar level or if you are diabetic and your cells are unable to absorb the sugar from your blood) then your brain will stimulate your α cells to release glucagon to increase your blood sugar levels. In the presence of insulin, your body cells will be able to absorb the extra glucose from your blood in order to carry out their functions. However, if you are diabetic, your body cells will still be unable to absorb the glucose from your blood. This means that the glucagon released by your α cells will have further increased your blood sugar level above the normal range but the cells of your body are still starved of glucose (which is the fuel that they need to carry out their functions). High blood sugar levels causes hyperglycaemia which can induce numerous complications in the short term and increases your risk of developing heart disease in the long term.

Diabetes & β cells

Beta (β) cells are found within the region of your pancreas known as the Islets of Langerhans. The Islets of Langerhans contain the endocrine cells of your pancreas that release chemical messengers (hormones) into your blood stream in order to affect other organs of your body.  β cells are the endocrine cells responsible for releasing the hormone called insulin that binds onto the cells of your body (such as muscle cells) in order to allow them to absorb glucose (sugar) from your blood.  β cells are stimulated to release insulin into your blood stream when your blood sugar levels are high. This both makes the sugar available for the cells of your body and also ensures that your blood sugar level remains within a normal range (4.4-6.1mmol/L). If you are diabetic then after a meal your brain will still recognise a high blood sugar level and stimulate your β cells to release insulin, but the cells of your body will not be able to absorb any of the sugar either because your body is unable to respond to insulin (type II diabetes) or because it is unable to produce insulin (type I diabetes). This means that the cells of your body will still be signalling your brain that they require more glucose and this could cause your brain to stimulate the α cells of your pancreas to release glucagon (which is a hormone that has the opposite effect to insulin, by stimulating the release of more glucose into your blood stream). This could lead to your blood sugar level increasing further! This is why, if you are diabetic, you will either need to very careful control your diet or inject yourself with insulin in order to manage your blood sugar level in the absence of the ability of your body to manage it itself.  

Diabetes & γ cells

Gamma (γ) cells is the name occasionally given to cells within the Islets of Langerhans region of the pancreas other than the α and β cells (than secrete glucagon and insulin respectively) and are generally regulating hormones that help to keep your blood sugar level within the normal range. Now adays these cells are broken up into classes of cells that all have slightly different functions; delta (δ) cells, PP cells and epsilon (ε) cells. The delta cells release a hormone called somatostatin which acts to regulate your hormone system. The PP cells release pancreatic polypeptides (especially after a meal) in order to help to regulate the amount of stored glucose (sugar) released by your liver, although the amount of pancreatic polypeptides in your blood is seen to decrease when your delta cells release somatostatin. Lastly, the epsilon cells release a hormone known as ghrelin which stimulate the feeling of hunger. If you are diabetic, the balance between the amount of insulin and glucagon in your blood will be off due to either your inability to respond to insulin or your inability to produce insulin. This means that your γ cells will also be off balance and your may have feelings of hunger more often (particularly in diabetes type II) or you may find that you lose weight (particularly in diabetes type I).

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