Understanding Diabetes

Introduction

How widespread is diabetes?

If you have just found out that you have diabetes, this doesn’t mean that you have become sick or turned into an invalid. Millions of people in this country have diabetes and most lead normal, active lives. Some have had the condition for over 50 years.
With advances in our understanding of the disease and improvements in treatment, the prospects for someone with diabetes are better than ever before. This book is meant to help you understand what diabetes is and how to control it.

Personal responsibility

Doctors nowadays encourage people with diabetes to take a lot of responsibility for their own health, paying careful attention to their diet and carrying out regular tests on their blood and urine in order to monitor their progress. We explain, step by step, how you can do this and how you can develop confidence that you really are in control of your diabetes.

The history of diabetes

Diabetes is one of the oldest known human diseases. Its full name – diabetes mellitus – comes from the Greek words for syphon and sugar, and describes the most obvious symptom of uncontrolled diabetes: the passing of large amounts of urine that is sweet because it contains sugar (glucose). There are descriptions of the symptoms by the ancient Persians, Indians and Egyptians, but a proper understanding of the condition has developed only over the last hundred years or so.

The discovery of insulin

In the later part of the nineteenth century, two German doctors worked out that the pancreas – a large gland behind the stomach – must be producing some substance that stopped the level of blood glucose rising.

In 1921 three Canadian scientists isolated the mystery substance, which they named insulin, from small groups of cells within the pancreas called the islets of Langerhans.

When insulin became available as a treatment for diabetes after 1922, it was seen as a medical miracle, transforming the future prospects of those with the condition, and saving the lives of many young people who would otherwise have died after a painful wasting illness.
Some 30 years later, it was found that one form of diabetes could be treated with tablets to lower levels of blood glucose. This new development led doctors to distinguish two forms of the condition.

Type 1 diabetes - IDDM (insulin-dependent diabetes mellitus)

This starts most commonly in younger patients who have to have regular injections of insulin to remain well.

Type 2 diabetes - NIDDM (non-insulin-dependent diabetes mellitus)

Also called age-related or maturity-onset diabetes, this is more common in middle or later life and can be controlled by tablets or just diet.

What is diabetes?

Diabetes is a permanent change in your internal chemistry that results in you having too much glucose in your blood. The cause is a deficiency of the hormone insulin.

A hormone is a chemical messenger that is made in one part of the body (in this case the pancreas) and released into the bloodstream to have an effect on more distant parts.

There may be complete failure of insulin production as in type 1. In type 2, however, there is usually a combination of a partial failure of insulin production and a reduced body response to the hormone. This is called insulin resistance.

What goes wrong?

The glucose in your blood comes from the digestion of food and the chemical changes made to it by the liver. Some glucose is stored and some is used for energy. Insulin has a unique shape that plugs into special sockets or receptors on the surface of cells throughout the body. By plugging into these receptors, insulin makes cells extract glucose from the blood and also prevents them from breaking down proteins and fat.

It is the only hormone that can reduce blood glucose, and does this in several ways:

• By increasing the amount of glucose stored in the liver in the form of glycogen
• By preventing the liver from releasing too much glucose
• By encouraging cells elsewhere in the body to take up glucose
• By preventing cells elsewhere in the body from breaking down protein and fat.

Other mechanisms in the body work together with insulin to help maintain the correct level of blood glucose. Insulin is the only means that the body has of actually lowering blood glucose levels, however, so, when the insulin supply fails, the whole system goes out of balance. After a meal, there is no brake on the glucose absorbed from what you’ve eaten, and the level in your blood goes on rising. When the concentration rises above a certain level, the glucose starts to spill out of the bloodstream into the urine. Infections such as cystitis and thrush (candida infection) can develop more easily when the urine is sweet because the germs responsible can grow more rapidly.

Passing more urine

Another consequence of rising blood glucose is a tendency to pass more urine. This is because the extra glucose in the blood is filtered out by the kidneys, which try to dispose of it by excreting more salt and water. This excess urine production is called polyuria and is often the earliest sign of diabetes.

If nothing is done to halt this process, the person will quickly become dehydrated and thirsty. As previously mentioned, as well as regulating blood glucose, insulin acts to prevent weight loss and help build up body tissue – so a person whose supply has failed or isn’t working properly will inevitably lose some weight.

Symptoms of diabetes - signs of diabetes

The severity of the symptoms and the rate at which they develop may differ depending on which type of diabetes you have. Symptoms caused by type 1 and type 2 diabetes:

• Thirst
• Dehydration
• Passing large quantities of urine
• Urinary tract infection (such as cystitis) or thrush
• Weight loss
• Tiredness and lethargy
• Blurred vision resulting from dehydration of the lens in the eye.

Ketoacidotic coma

Type 1 - Diabetes 1

As the person isn’t producing any insulin at all, the symptoms can come on very rapidly because internal blood glucose control is lost.
Insulin has a very important role in maintaining stability in the body by preventing breakdown of proteins (found in muscle) and fats. When insulin fails, the byproducts of the breakdown of fat and muscle build up in the blood and lead to the production of substances called ketones. If nothing is done to stop this, the level will rise, until eventually it causes the person to go into what’s called a ketoacidotic coma.
This is much less common these days because diabetes is usually diagnosed long before coma develops. However, when it occurs patients need urgent hospital treatment with insulin and fluids into a vein. This is not the same thing as a coma induced by low blood sugar (or hypoglycaemia).

Type 2 - Diabetes 2

As the supply of insulin is reduced or is not quite as effective as normal, the blood glucose level rises more slowly. There is less protein and fat breakdown so ketones are produced in much smaller quantities, and the risk of a ketoacidotic coma is lower.

Who gets diabetes?

Almost four per cent of people in this country have diabetes, although as many as half of them may not realise it. This number is steadily increasing. The vast majority have type 2, and more women than men are affected, probably because diabetes is more common later in life and women tend to live longer. As the age of the population as a whole is rising, type 2 diabetes is likely to become even more common over the coming years.

In addition, the incidence of diabetes is increasing worldwide and is estimated to result in a near doubling of the population with type 2 diabetes by 2025.

Moreover, children in the UK seem to be developing type 1 diabetes at an earlier age, and there are increasing numbers of patients developing type 2 diabetes in early adulthood.

What causes diabetes?

There are many reasons why insulin secretions may be reduced and an individual could be affected by more than one cause.

Estimated diagnosed diabetes by type and country for the UK in 2005
 

Genetic

Researchers studying identical twins and the family trees of patients with diabetes have found that heredity is an important factor in both kinds of diabetes. With type 1 diabetes, there is about a 50 per cent chance of the second twin developing the condition if the first one has it, and a 5 per cent chance of the child of an affected parent developing it.

With type 2 diabetes, it is virtually certain that, if one of a pair of identical twins develops it, the other will do so as well.
It is difficult to predict precisely who will inherit the condition. A small number of families have a much stronger tendency to develop diabetes and scientists have identified several genes that seem to be involved. In these circumstances, it may be possible to test family members and determine their risk of developing the condition. For the most part, however, it is difficult to identify the genes involved and this makes it different from some other conditions such as cystic fibrosis, where a single gene is operating.

So even if a close member of your family has diabetes, there is no certainty that you will develop it yourself. Some people who inherit a tendency to diabetes never actually get it, so there are obviously other factors at work here.

Infection

It has been known for some time that type 1 diabetes in children and young people is more likely to come on at certain times of the year when there are a lot of coughs and colds about.

Some viruses, such as the mumps virus and Coxsackie virus, are known to have the potential to damage the pancreas, bringing on diabetes. As far as individual patients are concerned, however, it is very rare that doctors can link the onset of their diabetes with a specific bout of infection. A possible explanation for this is that the infection may have begun a process that comes to light only many years later.

Environment

People who develop type 2 diabetes are often overweight and eat an unbalanced diet. It’s interesting to

note that people who move from a country with a low risk of diabetes to one where there’s a higher risk have the same chance of developing diabetes as the locals in their new country.

There is a close link between body weight and the development of type 2 diabetes. Recent surveys have shown a dramatic increase in obesity in the UK, especially in young people, and this is partly responsible for the increasing incidence of diabetes.
A good example of this is shown by the Pacific islanders of Nauru who became very wealthy when phosphates were discovered on their island. As a consequence, their diets changed dramatically; they put on a lot of weight and they became much more prone to developing diabetes.
All this points to important connections of diet, environment and diabetes. However, there is no precise link between developing diabetes and the individual consumption of sugar and sweets.

Secondary diabetes

There are a small number of people who develop diabetes as a result of other disease of the pancreas. For example, pancreatitis (or inflammation of the pancreas) can bring on the condition by destroying large parts of the gland. Some people with hormonal diseases, such as Cushing’s syndrome (the body makes too much steroid hormone) or acromegaly (the body makes too much growth hormone), may also have diabetes as a side effect of their main illness.

It can also be a result of damage to the pancreas caused by chronic over-indulgence in alcohol. Some long-term treatments such as steroids and beta-blocker tablets are also associated with an increased rate of development of diabetes.

Stress

Although many people relate the onset of their diabetes to a stressful event such as an accident or other illness, it is difficult to prove a direct link between stress and diabetes. The explanation may lie in the fact that people see their doctors because of some stressful event, and their diabetes is diagnosed opportunistically at the same time.

KEY POINTS

• Diabetes arises when either an individual cannot make enough insulin or the insulin that an individual does make is ineffective at controlling blood glucose levels

• Insulin is a hormone (chemical messenger) that is critical for maintaining healthy life

• Symptoms of diabetes are weight loss, passing more urine, thirst and feeling run down

• There are several causes including genetic (inherited) predisposition, infections, obesity, environmental factors and possibly stress, and any or all of these may be important in each individual case

• Being overweight greatly increases your chances of developing type 2 diabetes