Potential benefits of dietary changes or supplementation should now be studied to see if they can modify these women's risk, researchers said.
Dr Madona Azar and colleagues from the University of Oklahoma took measurements from 47 women with type-1 diabetes. Data from 23 women who subsequently developed pre-eclampsia were matched with 24 controls.
Previous studies have linked pre-eclampsia risk with vitamin D levels. But Dr Azar and her team believe their study is the first longitudinal study of the link between pre-eclampsia in type-1 diabetes and levels of carotenoids and vitamins.
The researchers measured serum levels of the carotenoids alpha-carotene, beta-carotene, as well as lycopene and lutein at 12 weeks, 22 weeks and 32 weeks. They also studied levels of vitamins A, D and E at the same time intervals.
Dr Azar and colleagues found that levels of alphaand beta-carotene in women who went on to develop pre-eclampsia were around half those in women who did not develop the condition.
They also found that lipid-adjusted levels of many fat-soluble antioxidants declined during pregnancy.
Most of the women enrolled in the study were vitamin D deficient. Vitamin D levels appeared to be lower in those who developed pre-eclampsia, but this difference was not statistically significant.
These low vitamin D levels might be partly a result of undiagnosed coeliac disease, which can cause vitamin D absorption problems and occurs in up to 10 per cent of people with type-1 diabetes.
However, the researchers did not collect information on dietary intake. They said that such information would be useful to help 'dissect cause and effect'. 'Further studies are needed to define whether optimising fat-soluble antioxidant and vitamin status throughout pregnancy can reduce the high incidence of pre-eclampsia in those with type-1 diabetes,' they concluded.