The number of people with diabetes in the UK has risen by more than 167,000 since last year to nearly 2.5 million, a charity said today.

The sharp increase, to 2,488,814, is more than double the 83,000 rise in the number of diabetics from 2006-07.

The number of people with diabetes in England has passed 2 million for the first time, due to a 6.4% rise in diagnoses, said the charity Diabetes UK.

The number of people with diabetes rose by 6.8% in Northern Ireland and 6% in Wales over the same period. Scotland experienced the biggest rise in the UK - 16.7% - partly due to improved recording of cases.

About 90% of people with diabetes have the type 2 form of the disease, which is strongly associated with obesity and lifestyle. There are about 5 million obese people in the UK, compared with almost 4.8 million last year.

Douglas Smallwood, the chief executive of Diabetes UK, said the figures were "truly alarming". Although part of the rise could be explained by improvements in diagnosing the condition, he said the main factor was the UK's "obesity crisis".

He said: "The soaring diabetes prevalence will continue to put a massive strain on an already struggling NHS and unless it can respond, people's health could spiral downwards.

"We need to do all we can to raise awareness of the seriousness of diabetes and help people understand how a healthy lifestyle can help reduce their risk of developing type 2 diabetes."

Diabetes causes heart disease, stroke, amputations, kidney failure and blindness, and more deaths than breast and prostate cancer combined.

Diabetes UK estimates there are more than 500,000 people in the UK who have type 2 diabetes but do not know it.

The condition can go undetected for up to 10 years. Half of people with the disease already have symptoms and complications by the time they are diagnosed, according to the charity.