Diabetes mellitus is a disorder in which there is too much sugar in the blood. It is caused by a lack of an important hormone called insulin, which is made by a gland behind the stomach called the pancreas. Diabetes comes from a Greek word meaning 'to pass or flow through' and mellitus means 'sweet'.

Insulin controls the balance of sugar (glucose) in the body and allows the cells in the body to absorb the glucose from the bloodstream. Lack of insulin causes glucose to spill out from the blood through the kidneys into the urine.

What are the two main types of diabetes?

Type I diabetes is known as juvenile-onset diabetes or insulin-dependent diabetes mellitus. It occurs mainly in young people, and because their pancreas produces very little insulin they require injections of insulin. The cause is not known exactly.

Type II diabetes is known as maturity-onset diabetes or non-insulin-dependent diabetes mellitus. It mainly affects people over 40, many of whom are overweight and have a diet with excess calories. They do not produce enough insulin to cope with the large supply of glucose in their systems. It is usually controlled by a proper diet only, but sometimes tablets may have to be used.

What are the symptoms?

The classical symptoms of untreated diabetes are:

• excessive and frequent urination (every hour or so)
• excessive thirst
• loss of weight (mainly in type I)
• tiredness and lack of energy
• a tendency to get infections, especially of the skin
• cramps in the legs
• itching, especially in the genital area

How common is the problem?

About 1 person in 30 gets diabetes. It tends to increase as we get older because the pancreas, like other organs, tends to wear out. However, those at greatest risk are older people who are overweight and have a family history of diabetes.

What are the risks?

Modern treatment is very effective for diabetes, but the results depend on the patient following the treatment, especially the diet. If diabetes is untreated, the complications are very severe and include coma (from either the blood sugar being too high or too low), kidney disease, blindness, heart disease and other problems caused by hardening of the arteries. The feet and eyes are at special risk and need special care and regular checks.

Can diabetes be cured?

No, not yet, but it can virtually always be controlled by a proper diet and regular exercise, and if necessary insulin or special tablets. Although the diagnosis comes as a shock to patients, it is not the major problem that it is generally believed to be-most patients lead normal lives.

Is diet the main treatment?

Yes; all diabetics require a special diet in which carbohydrate and fat intake is controlled. The objectives of the diet are:

• to keep to ideal weight (neither fat nor thin)
• to keep the blood sugar level normal and the urine free of sugar

This is achieved by:

• eating good food regularly (not skimping)
• spacing the meals throughout the day (three main meals and three snacks)
• cutting down fat to a minimum
• avoiding sugar and refined carbohydrates (e.g. sugar, jam, honey, chocolates, sweets, pastries, cakes, soft drinks)
• eating a balance of more natural carbohydrates (starchy foods) such as wholemeal bread, potatoes and cereals
• eating a good variety of fruit and vegetables
• cutting out alcohol or drinking only a little

Is exercise important?

Yes-it really benefits your health. Exercise is any physical activity that keeps you fit. Good examples are brisk walking (e.g. 2 km per day), jogging, tennis, skiing and aerobics. Aim for at least 30 minutes 3 times a week, but daily is ideal. Go slowly when you start.

Good advice

Here are 10 important recommendations:

1. Exercise is important.
2. Do not get overweight.
3. A proper diet is the key to success.
4. A low-fat, no-sugar diet is needed.
5. A high-fibre diet is great.
6. Do not smoke.
7. Minimise alcohol.
8. Take special care of your feet.
9. Seek medical advice if you get the flu or any other infection or if your blood tests are not good.
10. Self-discipline will help make your life normal.

Copyright 1995: John Murtagh, Professor of General Practice
Monash University, Melbourne, Australia