Letters are being sent out in batches to 1.8 million Singaporeans aged 40 years and older, inviting them to go for health screening for up to five diseases by paying $5 at most. All the letters will be sent out by the year end.

The Enhanced Screen for Life, announced by Senior Minister of State for Health Chee Hong Tat during the parliamentary debate on his ministry's Budget in March this year, starts tomorrow.

Under it, all eligible people can be screened for diabetes, high blood pressure and high cholesterol levels. Woman can be screened for cervical cancer, and people aged 50 years and older can test for colorectal cancer.

The screening, which is free for pioneers, costs $2 for those with the Community Health Assist Scheme card, and $5 for others. The screening includes a consultation with a doctor when the results are known, and can be done at more than 1,000 general practice clinics in the scheme.

Mr Chee told The Straits Times: "The aim of enhancing Screen For Life is to encourage Singaporeans to go for regular health screening, so that any problems can be detected early and better managed with appropriate intervention.

"Together with healthy eating and regular exercise, this is part of our collective efforts to keep Singaporeans healthy and lower the risk of diabetes and other chronic diseases."

Ms Jacqueline Enoch, 47, a manager at the Singapore Green Building Council, plans to go for the screening with her husband, also aged 47, and her mother, 77.

Her mother has high blood pressure and diabetes, but has not been tested for colorectal cancer. She was persuaded to go for screening after Prime Minister Lee Hsien Loong encouraged people to do so in his National Day Rally address.

Ms Enoch herself has not gone for a pap smear to check for cervical cancer since her second child was born 17 years ago.

Explaining her reasons, she said: "The cost is rather high. And we have to personally go to the polyclinic to make an appointment, then go again for the test."

The scheme allows her to take the test at a general practice clinic, which she finds very convenient.

While all 1.8 million people will get the invitation letters, some like Ms Enoch's mother will not need to screen for everything since she already knows of her chronic conditions and is being treated for them.

However, there are still many who are unaware that they might be suffering from some of these conditions.

The 2010 national health survey found that more than half of those with diabetes did not know of it, more than one in four were not aware they had high blood pressure, and 44 per cent found out they had high cholesterol levels for the first time because of the survey.

The ministry hopes the offer of free or cheap screening will alert people with chronic conditions to become aware they have them, and encourage them to take steps to keep their conditions under control.

The subsidised screening is available every three years for those who have no known chronic ailments.