The study, led by UC Davis researchers, was published online in Archives of Dermatology, and found a strong association between the dry skin rash and blood sugar disorder.
Psoriasis is widespread skin condition that runs in families. It is characterized by red, raised, flaky and often itchy, rash, and is found mostly on the knees and elbows, but can appear anywhere. Doctors believe it is an autoimmune disease; the body thinks of the skin as foreign and therefore gives off an inflammatory response. Earlier studies have hinted that psoriasis could be a risk factor for diabetes.
April Armstrong, assistant professor of dermatology at UC Davis and lead investigator of this study, and her team examined 27 studies of patients with psoriasis. Five of these studies looked at how many of the patients developed diabetes during the period of study, 10 to 22 years. The remainder of the studies assessed the incidence of diabetes at the commencement of the study. In total, they examined over 314,000 people with psoriasis and compared them with 3.7 million people without the disease (a control group).
The collection of data for these studies shows that patients with mild psoriasis are more than 1.5 times more likely to develop diabetes than the general public, while those suffering from severe psoriasis are twice as likely.
Studies that assessed prevalence found patients with psoriasis had a 27 percent elevated risk of getting diabetes, compared with the general public.
All but one study found a link between psoriasis and diabetes. These trials contained data from outpatient clinics, insurance claims, and hospitals. The rate of diabetes was the same regardless of patients' ethnicities or countries. Armstrong explains:
"The large sample size and consistent association between psoriasis and diabetes make these study findings very strong and suggest an underlying physiological link between the two diseases."
The authors admit that additional research is needed to interpret how the two diseases are intertwined. Armstrong suggests changed immune pathways may be responsible for making psoriasis patients more vulnerable to diabetes.
She goes on to say:
"There is evidence that fat cells in psoriasis patients may not function normally. These cells secrete inflammatory substances known as cytokines that increase insulin resistance in the liver and muscle and initiate destruction of insulin-producing cells in the pancreas."
More research can also verify other possible limiting factors that are seen in the current study; a factor that could be confusing, like concurrent medications used to treat psoriasis that may change the risk of developing diabetes.
It has been known that blood pressure is harder to control in patients with psoriasis and also that psoriasis patients suffer higher instances of heart attack, strokes, and cardiovascular-related deaths. In order to provide the best and earliest care, it is imperative for physicians to be aware of these predispositions.
Armstrong and her team plan to study endothelial cells, cells that line the blood vessels, in order to interpret the unseen physiological basis of psoriasis. They will soon create a network to share clinical data on patients with psoriasis.
Written by Kelly Fitzgerald