WHAT do former Celtic and Scotland defender Danny McGrain and one of Britain's greatest-ever Olympians, Sir Steve Redgrave, have in common?

Both were successful sportsmen who represented their country on the international stage, and both were generally considered as the best in their respective sports by supporters and opponents alike.

The link? Both were diagnosed with diabetes during their careers and had to overcome the difficulties of managing the condition while maintaining optimal levels of performance.

Diabetes is a condition where there is an excess of glucose (sugar) in the blood caused by a lack of the hormone insulin, produced by the pancreas gland, which is situated in our abdomen close to the liver - 1.5million people in the UK have diabetes with an estimated further one million having diabetes without knowing it.

Diabetes results in damage to the heart, kidneys, circulation, nerves and eyes leading to heart attacks, blindness, kidney failure and strokes. There are two types of diabetes.

In Type 1, the body does not produce any insulin and sufferers have to inject insulin up to four times a day. Type 1 diabetes typically develops in children or young adults.

There is some evidence that it may be inherited or triggered by an environmental factor. In Type 2, the body still manages to produce some insulin, but it is not enough or does not work correctly.

When we eat food, glucose is produced and, in the absence of sufficient insulin, the level of glucose in the blood rises.

This results in the classical symptoms of diabetes - excessive thirst, passing urine frequently, tiredness, low energy, blurred vision and weight loss.

The ever-rising rate of childhood obesity has sparked a warning that a similar escalation in the number of diabetics will follow.

Worldwide more than 22million children under five years old and 10% of school children are overweight, and at much higher risk of developing diabetes. It is ironic that Type 2 diabetes used to be known as adult onset diabetes.

However, a combination of poor diet and lack of exercise in children has resulted in this type of diabetes appearing in teenagers!

A study in the US suggests that eating "junk food" more that twice a week has strong links with obesity and the development of diabetes.

Action needs to be taken now to reduce this "obesity epidemic".

Small changes can make a big difference - less fizzy juice, reduced portion sizes, leaner meat and lower fat additives, combined with better education on nutrition and, importantly, increasing children's activity levels.

Sport and activity have a major part to play in the reversal of the potential diabetes epidemic. Children respect, listen to and try to act like their sporting heroes.

This is never as important as in diabetes, where exercise is part of the treatment programme. The general benefits of exercise, particularly on the heart and circulation, are even more important in those with diabetes.

Activity lowers blood sugar levels and those who exercise regularly often need less insulin.

High-intensity exercise will need tighter blood sugar control and more careful dietary modification with snacks available to prevent too low blood sugars.

Some sports such as water sports or climbing may need some medical supervision but, in general, there is no reason why those with diabetes can't do any sport they like.

A hundred years ago Type 1 diabetes was a death sentence.

Now people like McGrain and Redgrave, as well as many well-known actors such as Tom Hanks, Sharon Stone and Halle Berry can, and do, inspire young people with diabetes to believe they can do anything they wish and be a totally normal person.