All adults aged 40 and above should have a risk assessment for type 2 diabetes, according to the healthcare watchdog.

The National Institute for Health and Clinical Excellence (Nice) has also recommended that people aged 25 and above of South Asian, Chinese, African-Caribbean or Black African descent, who are at a higher risk, should also perform a test.

People can be assessed at their GP surgery or community pharmacy but they can also perform self assessments online.

Nice said the new recommendations will help to identify people at high risk so they can be offered advice to help them prevent or delay the condition.

The body also recommends that health and community services, workplaces, job centres, faith centres, libraries and shops should offer risk assessments so they are more widely available.

If someone is identified as high risk they should contact their GP for a blood test to confirm the level of risk, the new Nice guidelines suggest.

Nice also recommends that people who are identified as high risk should be given an "evidence-based, intensive lifestyle-change programme" to prevent or delay the onset of type 2 diabetes.

Type 2 diabetes is a long-term condition that occurs when the body does not produce enough insulin for it to function properly, or when the body's cells do not use insulin properly.

Diabetes currently affects almost three million people in the UK, of which about 90% will have type 2 diabetes.

Professor Mike Kelly, director of the Centre for Public Health Excellence at Nice, said: "Almost three million people are currently affected by diabetes, and it is likely to affect many more in the future.

"Type 2 diabetes is a very large-scale problem and it is important for people to know that it is preventable, and there are simple steps that can be taken to help reduce the risk of developing the disease.

"This guidance will help people to identify their own personal risk and highlights that by losing weight, being more active and improving their diet, they can prevent or delay type 2 diabetes."

Birmingham Community Healthcare Trust diabetes nurse consultant Jill Hill added: "As a diabetes nurse, I have seen first-hand how the condition can affect a person's life.

"People may not be aware that diabetes is the most common cause of visual impairment and blindness, kidney failure and non-traumatic lower limb amputations.

"This guidance focuses on risk assessment and providing those at high risk with evidence-based, effective interventions that can delay or prevent this condition."

Barbara Young, chief executive of Diabetes UK, said: "We welcome this excellent guidance document, which gives strong evidence that identifying people at high risk of type 2 diabetes is a vital part of preventing the condition and can also help diagnose those who have it earlier so that they can be helped to avoid serious complications developing.

"We want to see the recommendations in this guidance to be fully implemented because the number of people with type 2 is increasing at an alarming rate and it is only through prevention that we will be able to stem the rising tide and cost of type 2 diabetes."