Obesity and type 2 diabetes have both been linked to psoriasis in a recent study on Danish twins. But how can carrying excess pounds possibly lead to the chronic skin condition?
Psoriasis – marked by skin inflammation resulting in patches of itchy red and pink marks – has previously been associated with components of metabolic syndrome, a cluster of health indicators that include obesity and diabetes. The link could be explained by different factors, perhaps genetics or lifestyle habits such as alcohol intake.
Researchers from the University of Copenhagen in Denmark probed the link further by assessing data from 33,588 twins, more than half of which were women.
They found that the risk for obesity – a body mass index (BMI) greater than 30 – was higher in psoriasis patients, with the likelihood of obesity climbing as BMI was increasing. They also noted that the average BMI of individuals with psoriasis was higher than those without the skin disorder, or a BMI of 25 versus 24.4.
Furthermore, twins with psoriasis exhibited a higher BMI than twins without the skin disease – and they surfaced as more likely to be obese, too.
“Results indicate a common genetic etiology of psoriasis and obesity,” concluded the researchers in their study published in the journal JAMA Dermatology.
The findings, while not providing direct causation, add to the mounting body of research showing the link between obesity and psoriasis, which could emerge from either case: psoriasis predisposing individuals to a more sedentary lifestyle and therefore behaviors that promote obesity and diabetes, or both obesity and diabetes driving psoriasis.
In an accompanying editorial, Dr. Joel Gelfand of the University of Pennsylvania said that the unique twin design of the study offers a new genetic dimension to earlier findings. According to him, both old and new studies observed that psoriasis goes beyond being a skin disease – it is backed by systemic health issues.
Other studies, he added, have found that psoriasis patients are more likely to develop type 2 diabetes even without major risk factors for the blood sugar condition, with the risk increasing along with the severity of their psoriasis case.
“Some of the risk may be due to shared genetics between psoriasis and diabetes,” Gelfand explained. “It is also thought that chronic inflammation in psoriasis may predispose patients to diabetes.”
To explore the gene connection further, genetic variations in IL12B, IL23R and IL23A genes have been seen to influence not only psoriasis risk, but also the severity of both the skin disorder and type 2 diabetes. Other researchers have also suggested the role of the CDKAL1 gene in psoriasis and diabetes predisposition.
Gelfand urged psoriasis patients, particularly those ages 40 to 70 with greater severity, should get medically screened for diabetes. Overweight or obese ones may also lower their diabetes risk and render their skin disease less active by maintaining a healthy weight.
