More than four million Britons will have diabetes by 2025, a 46% rise mostly fuelled by the obesity crisis, figures show today.

If the trend was confirmed in Scotland, the increase would bring the total number of people with diabetes to an estimated 371,000.

Unhealthy diets and a lack of exercise will lead to a "diabetes explosion", according to the charity Diabetes UK.

Currently, just under 200,000 people in Scotland are diagnosed with diabetes, with an estimated 60,000 undiagnosed. In the UK, more than 2.3 million people are diagnosed with diabetes and more than 500,000 also have the condition but are not aware of it.

New population estimates from the Yorkshire and Humber Public Health Observatory would mean an additional 1.3 million people with the condition by 2025 in the UK, the equivalent of a 46% increase, bringing the total number of people with diabetes to an estimated 4.2 million.

Most of the increase will be due to rising numbers of overweight or obese people in the UK: 80% of people diagnosed with Type 2 diabetes are overweight at the time of diagnosis.

The increase will have major consequences on the general health of the UK population as diabetes is a serious condition that can lead to devastating complications including heart disease, blindness, kidney disease and amputation.

It will also mean higher costs for the NHS in Scotland which already spends a tenth of its budget treating diabetes and its complications.

Audrey Birt, Diabetes UK Scotland's National Director, said: "These new figures are shocking and confirm diabetes is one of the main health challenges facing the UK. Awareness and prevention are crucial if we want to avert this future health crisis. We need to encourage people to reduce their risk of developing the condition by eating healthily, maintaining a healthy weight and leading an active lifestyle."

Tam Fry, board member of the National Obesity Forum, said: "The real tragedy of this increase in diabetes Type 2 is that so many of them will be children with what is essentially a mid-life condition.

"This is the generation of children who may well be the ones who die before their parents."

Charity warns that Britain could see 46% rise by 2025

Diabetes UK published five top tips for preventing diabetes, urging people to eat a diet low in salt, sugar and fat with lots of fruit and vegetables. Being physically active can cut the risk of developing Type 2 diabetes by up to 64% while quitting smoking cuts the risk of heart disease, which is linked to diabetes, it said.

It also urged people to keep their waists trim. Men with a 37in or higher waist (or 35in plus for men of South Asian origin) and women with a 31.5in or higher waist are at increased risk of Type 2 diabetes.

Finally, the charity urges people to get checked out by their GP. Type 2 diabetes can be undetected for up to 12 years and half of people already have serious complications by the time they are diagnosed.

Diabetes UK is committed to funding more than £7m of medical research every year to investigate the causes and prevention of diabetes, to improve care and treatment of diabetes and ultimately to work towards a cure.

The charity is running a series of fundraising activities throughout Diabetes Week to help raise much-needed funds.

I worry about the future. For example, can I have children?'

CASE study
THE diabetes timebomb could leave Scotland with a 46% increase in cases - with their complications like vascular disease and blindness - by the year 2025, experts warned yesterday. Jill Daly had no advance warning. Diagnosed at the age of two, she lost her sight abruptly at the age of 19. Now a presenter with Insight, the Glasgow radio station for blind listeners, she tries to live a life as full as possible - as she told of her experience, she and a friend were preparing to camp for the night on the shores of Loch Ness. "I lost my sight over two weeks," said Jill. "I threw myself into a lot of different things to keep my mind off what was happening." There have been other health complications and Jill said: "I worry about the future - for example will I be able to have children? "Even if I can, will I be fit enough to be a mother? Would it be fair to have them if I couldn't look after them? "These things don't worry you so much in your 20s, but I am 31 now. I know pregnancy can be dangerous."