Dogs are man’s best friend, so much so that when a dog has diabetes, its owner is at an increased risk of developing type 2 diabetes, suggest new findings published in the journal The BMJ, reports Uppsala University in Sweden.

For the study, scientists at Uppsala University, the Swedish University of Agricultural Sciences and the Karolinska Institutet teamed with researchers at the University of Liverpool to identify adults in Sweden who lived with a dog or cat. Overall, more than 175,000 dog owners and almost 90,000 cat owners were located. All pet owners were middle-aged or older.

After following owners and their pets for six years, researchers found that owners of dogs with diabetes were 38% more likely to develop type 2 diabetes compared with those with dogs without the disease. No such connection was found between cat owners and their felines.

Scientists couldn’t explain why the risk of diabetes was higher for dog owners, even after looking at several factors such as the owners’ age, gender and socioeconomic status as well as the dogs’ age, gender or breed.

“We have not had access to information about households’ living habits, but we believe that the connection could, for example, be due to common exercise habits and perhaps also to some extent dietary habits and common risk of obesity,” said Beatrice Kennedy, MD, PhD, a postdoctoral fellow in medical epidemiology at Uppsala University, and one of the study’s lead authors. (Past studies have shown a possible link between obesity in dog owners and their canines.)

Kennedy added that if mutual exercise habits were a significant factor, this could also explain why researchers haven’t observed a similar diabetes risk shared between cat owners and their cats.

For related coverage, read “How Does Owning a Pet Affect Cancer Risk?” and “Animal Lovers Beware: Pets Can Pass Illnesses to Their Owners.”