"We knew there was some association between psoriasis and diabetes and high blood pressure," says Abrar Qureshi, MD, MPH, assistant professor of dermatology at Harvard Medical School and a dermatologist at Brigham and Women's Hospital, Boston. "The question was, which came first."
In the study, he tells WebMD, "We were able to show women with psoriasis had a higher risk of developing diabetes and hypertension."
The study is published in the April issue of the Archives of Dermatology.
Qureshi and colleagues studied 78,061 women who participated in the Nurses' Health Study II, a long-running study that first collected data in 1989 from more than 116,000 women (all registered nurses) and followed up with questionnaires about their health every two years.
All were free of diabetes and high blood pressure at the study's start. In 2005, the women reported whether they had ever gotten a diagnosis of psoriasis from a doctor. After excluding the women who already had diabetes or hypertension, the researchers focused on 78,061 women, including 1,813 with a diagnosis of psoriasis.
Psoriasis affects up to 3% of the population, according to the researchers. Five types occur, according to the American Academy of Dermatology, with different symptoms and signs. The most common is plaque psoriasis, marked by itchy patches of red, raised skin covered by a silvery-white scale that shows up most often on the elbows, knees, scalp, and lower back.