Both type 1 and type 2 diabetes sharply raise the risk of pregnancy complications, research has found.
Diabetes was linked to infant death
UK experts say diabetic women should be offered specialist foetal heart scans because of the increased risk of serious abnormalities and infant death.
The British Medical Journal study also advises diabetic women to take higher than usual doses of folic acid.
Researchers say that, with diabetes rates rising, it is vital that women are made aware of the risks.
The researchers, from the Confidential Enquiry into Maternal and Child Health, analysed the outcome of pregnancies in 2,359 women with diabetes. Of these 1,707 had type 1 diabetes and 652 had type 2 diabetes.
They found that the rate at which babies died shortly after birth was four times higher for women with both types of the disease compared with the general population.
For women with type 1 diabetes, the rate was 31.7 per 1,000 births, and for type 2 diabetes it was 32.3 per 1,000 births.
In both groups, the rate of major congenital anomaly, mainly heart and nervous system defects, was more than twice that of the general population.
For type 1 diabetes it was 48 per 1,000 births, and for type 2 diabetes it was 43 per 1,000 births.
The researchers said that in the past, type 2 diabetes had been viewed as a less serious condition than type 1 and may have been subject to less vigilant care.
They said with the number of cases of type 2 diabetes increasing, it was vital that people were aware of the associated risks.
They said women with diabetes should take 5mg of folic acid a day from before conception up to week 12 of pregnancy.
The vitamin is known to reduce the risk of neural tube defects, such as spina bifida.
Lack of awareness
Maggie Blott, a consultant obstetrician at London's King's College Hospital, said greater efforts had to be made to inform women about the risks of diabetes.
She also called for more pre-pregnancy counselling clinics to be established to offer expert advice to women thinking of trying for a child.
"Most women would be pretty aggressive about getting some sort of intervention if they knew they had a condition which significantly raised their risk of congenital abnormalities, but for some reason that message does not seem to have got across to people with diabetes."
Amanda Eden, of the charity Diabetes UK, agreed little progress had been made in tackling the problem.
She said: "Women with diabetes need to be made fully aware of the risks before they become pregnant.
"Then those looking after them need to ensure that all the right steps are being taken to allow women to effectively reduce those risks.
"It is unacceptable that women are losing their babies or giving birth to babies with major defects unnecessarily."
Ellen Mason, a cardiac nurse at the British Heart Foundation, warned that providing specialist heart screening could be problematical.
She said: "While improved early detection of such defects can lead to increasingly successful treatment for many children, there can be difficult choices for parents if complex heart defects are detected in pregnancy.
"Consequently, the obstetric services in the UK would need increased resources to support parents if more specialised foetal heart scans were undertaken."
A national framework for diabetes has been introduced since the study was carried out.