Children of mothers with diabetes have increased rates of early onset cardiovascular disease or CVD (conditions affecting the heart or blood vessels) from childhood up to the age of 40, the researchers have warned.

The increased rates were more pronounced among children of mothers with a history of CVD or diabetic complications, said the study published in the journal The BMJ.

"our study provides evidence that children of mothers with diabetes, especially those with a history of CVD or with diabetic complications, had increased rates of early onset CVD throughout the early decades of life," said study researchers from Aarhus University in Denmark.

If this association is shown to be causal, preventing, screening, and treating diabetes in women of childbearing age could be important not only for improving the health of the women but also for reducing long term risks of CVD in their offspring, the researchers added

The number of women diagnosed with diabetes before or during pregnancy has increased globally, and children of these women are more likely to have risk factors for future CVD, such as high blood pressure and high blood sugar levels.

It is unclear, however, whether or to what extent exposure to diabetes in the womb increases the risk of developing CVD in offspring over a lifetime.

So an international team of researchers set out to evaluate associations between diabetes diagnosed before or during pregnancy and early onset CVD in children during their first four decades of life.

They base their findings on national registry data for over 2.4 million children born without congenital heart disease in Denmark from 1977 to 2016.

Diabetes was categorised as pregestational (before pregnancy) or gestational (during pregnancy) and women with diabetic complications were identified.

Other potentially influential factors, such as mother's age, education, lifestyle and medical history were also taken into account.

During up to 40 years of follow-up, children of mothers with diabetes had a 29 per cent increased overall rate of early onset CVD compared with children of mothers who did not have diabetes (cumulative risks: 17.8 per cent vs 13.1 per cent ).

The researchers also found higher rates for specific types of CVD children of mothers with diabetes, particularly heart failure (45 per cent), hypertensive disease (78 per cent), deep vein thrombosis (82 per cent), and pulmonary embolism (91 per cent).

Increased rates were seen in each age group in childhood (before 20 years of age) and early adulthood (from 20 to 40 years of age), regardless of the type of diabetes they were exposed to (pregestational or gestational) and rates were similar for both type 1 and type 2 diabetes, the study said.