Middle-aged men with obese wives are significantly more likely to develop Type 2 diabetes than those with slimmer partners, scientists discovered.
A study of more than 3500 couples reveals a direct correlation between the weight of a woman and her husband’s health.
The reverse is not true, however, with overweight husbands having no impact on their wives’ chance of developing the condition.
Scientists interviewed English couples over the age of 50 every two-and-a-half years, between 1998 and 2015, tracking their weight and health for about 11 years.
They found that each woman’s weight at the beginning of the study was a strong predictor of her husband’s chances of developing Type 2 diabetes, irrespective of his own weight.
For every five additional points a woman scored on the body mass index scale, her husband was 21% more likely to develop the disease, regardless of his weight to begin with.
Scientists suspect shared lifestyle such as poor diet and lack of exercise is to blame, with obese women influencing their husband’s eating and activity patterns.
But the fact that men don't impact on their wives’ health suggests women have a much bigger influence on their husbands' lifestyle than men do on their wives.
This may be because women are more likely to cook their husbands’ meals, although experts stress the people assessed were middle-aged couples, so the same may not be true of younger groups.
Others said women may simply be more conscious of their appearance - making them more resistant to following their husbands’ lead.
Presenting their results to the annual meeting of the European Association for the Study of Diabetes in Portugal, the Danish researchers said men with overweight wives should be screened for diabetes.
Led by Adam Hulman of Aarhus University, they said: “This is the first study investigating the sex-specific effect of spousal obesity on diabetes risk. Having an obese wife increases a man’s risk of diabetes over and above the effect of his own obesity level, while among women, having an obese husband gives no additional diabetes risk beyond that of her own obesity level.
“Our results indicate that, on finding obesity in a person, screening of their spouse for diabetes may be justified.
"Recognising shared risk between spouses may improve diabetes detection and motivate couples to increase collaborative efforts to eat more healthily and boost their activity levels Obesity in one spouse may serve as a prompt for diabetes screening and regular weight checks in the other."
However, Dr Emily Burns of Diabetes UK said the findings might be out of date because family set-ups have changed.
“The data we’re looking at relates to the 1990s, so there’s a question around how relevant the results are today,” she said.