TWO TYPES OF DIABETES: HOW ARE THEY DIFFERENT?

Apr 23 2009

There is more than one type of diabetes, and you may hear things from your friends or relatives about diabetes and its treatment that apply to a form of diabetes that affects older people but not your child or yourself.

Type 1 diabetes mainly affects children and young people, particularly those under the age of thirty. This type of diabetes requires insulin for treatment because the pancreas makes insufficient insulin. It is called ‘Insulin Dependent Diabetes Mellitus’ (shortened to I.D.D.M.) for this reason.

Children may get insulin dependent diabetes

Diabetes affects about one in a thousand children, more in some countries and much less in others. It is most common in Caucasian people and is much less common in Asian people. We now believe that some people are born with an increased risk of developing this type of diabetes. This risk is inherited and helps to account for the fact that diabetes may occur in families and is more common in certain races than others.

The risk to develop diabetes is related to a system in the body called the immune system. The immune system is responsible for the body’s defense against infections and other foreign substances that can invade the body.

The immune system has genetic factors that are inherited — like everything else in the body — by a series of particular genes. There are a number of inherited factors that are concerned with this immune system. These factors are called human leukocyte antigens (HLA for short).

Everyone has a set of HLA factors — there are many different factors and we inherit a set rather like we inherit a blood group.

Certain HLA factors (the important ones are called DR3 and DR4) are linked with a risk to develop insulin dependent diabetes. We sometimes think of them as ‘genetic markers’ because they help us identify whether there is a risk for diabetes or not.

Those people that have the HLA factors that are linked with diabetes risk do not necessarily get diabetes though they have a much stronger chance to do so. We believe that something has to happen to bring on diabetes in such people.

We don’t really know what the precipitating factor is. Probably there are many factors which can do it. We do know that some viruses can precipitate diabetes in children and perhaps there may be other factors in the environment that we haven’t yet identified.

What happens then is that the body’s immune system may turn on its own pancreas and gradually damage the cells that make insulin. This process is called an auto-immune process.

When this process of damaging cells has proceeded to a point where most of the cells have been destroyed or damaged (about 80%) then the body can’t make enough insulin and diabetes develops. This process may take many years.

Older people may get non-insulin dependent diabetes

The other important type of diabetes is sometimes called Type 2 diabetes. This type of diabetes rarely affects children. It is common in older people (usually over thirty years of age) and it particularly affects people who are overweight. It probably occurs in 2% of people in our society though not all people who have this form of diabetes know that they have it in the early stages. In some other countries it is very much more common. This form of diabetes occurs, not so much because there is insufficient insulin, but because the insulin that is produced does not work properly. For this reason it is not dependent on insulin treatment so that it is called Non-Insulin Dependent Diabetes Mellitus (N.I.D.D.M.). It can often be treated by diet, weight reduction and tablets. Occasionally people with this type of diabetes however will benefit from insulin treatment.