When Adam King was 11 years old he developed mouth ulcers and constantly needed to drink water and urinate. His weight dropped to four and half stone but he was about to start a new school and it was put down to nerves.
Like 250,000 other people in the UK, Adam has Type 1 diabetes.
The condition, which usually appears before the age of 40, develops if the body is unable to produce any insulin, resulting in high blood sugar levels. Type 2 diabetes is more common and affects 1.9 million people in the UK, although a further 750,000 are thought to be undiagnosed. It develops when the body does not make enough insulin or when the insulin produced does not work properly. Although it is a genetic condition, it is lifestyle influenced. Most Type 2 diabetics are over-40 and overweight.
Adam is now 26 and a teacher at Ashford South Community Primary School in Kent. He injects insulin at least four times a day and regularly tests his blood sugar levels. "The main times to check are at the start of term and the start of the school holidays. Because I use less energy in the holidays I have to double my insulin uptake."
If he gets it wrong, he knows about it pretty quickly. Adam has often felt weak or light-headed in front of the class and has to eat something sugary straight away. "I carry cereal bars with me and have told the pupils about my diabetes so they aren't surprised if I have to eat in class. I've had to inject in front of them on school trips but they love it and want to learn more."
However, school can be a difficult environment for people with diabetes.
Not everyone feels comfortable about seeing people inject, and busy teachers don't always have the time to eat a proper lunch.
"Sometimes it's hard to make time to look after yourself as a teacher,"
Adam says, "which means I don't control my diabetes as much as I'd like.
But generally speaking it's about thinking ahead and reacting accordingly."
More schools are going to have to get used to diabetic teachers and pupils if the condition continues to rise. Incidence of Type 1 diabetes has doubled every year since 1945, and Diabetes UK estimates that there will be about 3 million Britons living with the condition by 2010.
Deaths from diabetes are also predicted to increase by 25 per cent in the next decade.
"If you look after diabetes, it'll look after you," says Libby Dowling, a care adviser for Diabetes UK and a trained paediatric diabetes nurse. Those who fail to manage it effectively can develop serious complications including blindness and kidney failure.
Libby says: "Most adults know what it feels like to have a hypo (when blood sugar levels get too low). They notice that they are becoming shaky, dizzy or hot or cold and will eat something before it gets out of hand.
"Problems can occur when teachers become stressed or anxious because this can affect their appetite, but diabetics have to keep their condition under control. They have to live with diabetes 24 hours a day, seven days a week.
You can't ignore it."
SYMPTOMS OF DIABETES
Early treatment will reduce the chances of developing serious health problems, so if any of these symptoms apply to you, ask your GP for a diabetes test:
* Increased thirst
* Going to the lavatory all the time - especially at night
* Extreme tiredness
* Weight loss
* Blurred vision
* Genital itching or regular episodes of thrush
* Slow healing of wounds