Women with diabetes should not take hormone replacement therapy, a study suggests.
Experts say more research is needed into HRT
Researchers in Denmark have found that women with the condition who take HRT increase their chances of dying early.
They say the pills can increase the risks of developing heart disease or having a heart attack.
Researchers from Hvidovre University Hospital studied 13,084 women over the age of 45, less than half of whom had taken HRT.
They found that women with diabetes who took HRT were up to three times more likely to die early compared to those without the condition.
Writing in the British Medical Journal, they said: "There was a significantly increased risk of death from all causes and from ischemic heart disease among women with diabetes."
The researchers were unable to explain these effects. However, they speculated it may be because the hormones adversely affected blood sugar levels.
The researchers also confirmed previous studies, dismissing claims that HRT can protect against heart disease.
At the moment we would not discourage women with diabetes from taking HRT
Eleanor Kennedy, Diabetes UK
They said: "Hormone replacement therapy does not protect women against death, ischemic heart disease or myocardial infarction."
Diabetes UK said further research is needed to determine whether HRT is unsafe for women with the condition.
Eleanor Kennedy, its research manager, said: "The use of HRT by women with diabetes is something which is being widely researched at the moment but the outcomes of studies have been inconclusive.
"Some indicate HRT has a positive effect on women with diabetes and some indicate the effect is negative. The study certainly adds to the debate on the subject but further research needs to be done.
"At the moment we would not discourage women with diabetes from taking HRT as it can offer proven health benefits in other areas. We look forward to studying the results of any further research into the subject."