Psoriasis and diabetes are two common chronic conditions that affect millions of people worldwide. There has been some research looking at the connection between psoriasis and diabetes, but what does it really mean if you have psoriasis – are you destined to develop diabetes as well? Let’s take a closer look at the relationship between these two conditions.
What is psoriasis?
Psoriasis is an autoimmune condition that causes skin cells to build up rapidly on the surface of the skin, leading to itchy, painful thickened patches that are often red and scaly. The most common form is plaque psoriasis, which causes clearly demarcated raised red lesions covered with silvery-white scales typically found on the scalp, elbows, knees and lower back. Psoriasis affects around 2-4% of the population and can develop at any age, though most commonly appears between ages 15-35 years old. The exact cause is unknown, but it’s believed to be related to genetics, immune system dysfunction, and environmental triggers. There is no cure for psoriasis, but various treatments can help control symptoms.
What is diabetes?
Diabetes is a chronic condition characterized by impaired ability to metabolize glucose due to insufficient insulin production (type 1 diabetes) or insulin resistance (type 2 diabetes). This results in high blood sugar levels. Symptoms include increased thirst, frequent urination, hunger, fatigue and blurry vision. If left uncontrolled, diabetes can cause serious complications like nerve damage, kidney disease, vision loss and heart disease. The prevalence of diabetes has been increasing steadily over the past few decades. Today, roughly 10% of the US population has diabetes.
The link between psoriasis and diabetes
1. Shared genetic factors
Research has identified certain genetic loci that are common risk factors for both psoriasis and type 2 diabetes. Specifically, variants in the CDKAL1 gene and near the HLA-C gene have been associated with increased risk of both conditions in Genome-wide association studies (GWAS). This suggests some degree of shared genetic susceptibility between psoriasis and type 2 diabetes. However, the genetic links only account for a small portion of overall disease risk.
2. Chronic inflammation
One of the major common denominators between psoriasis and diabetes is chronic inflammation. Psoriasis involves inflammatory processes that trigger excessive skin cell growth, while diabetes involves inflammation that disrupts normal insulin signaling pathways. There are certain inflammatory markers like C-reactive protein, TNF-alpha and IL-6 that are elevated in both psoriasis and diabetes patients compared to healthy controls. It is hypothesized that systemic inflammation from psoriasis could promote insulin resistance and development of diabetes.
3. Immune system dysfunction
Psoriasis is the result of overactive T-cells within the immune system causing skin inflammation. In type 1 diabetes, autoimmune destruction of insulin-producing pancreatic beta cells occurs. While different in mechanism, both involve dysfunction of immune pathways. Some research indicates that having an autoimmune condition like psoriasis may increase the risk of developing other autoimmune diseases.
4. Lifestyle factors
Certain lifestyle factors and comorbidities are associated with increased risks of both psoriasis and diabetes. For example, smoking, obesity, physical inactivity, high blood pressure and abnormal lipid levels have all been linked to higher incidence of psoriasis and diabetes in research studies. The chronic stress of living with a disease like psoriasis could potentially contribute to development of diabetes as well.
5. Medications
Some medications used to treat severe psoriasis, like corticosteroids and cyclosporine, have potential side effects that include elevated blood glucose and increased insulin resistance. This could make diabetics more difficult to control or predispose psoriasis patients to developing diabetes. However, many newer psoriasis biologic drugs do not seem to affect diabetes risk.
Epidemiological data on psoriasis and diabetes risk
Numerous large epidemiological studies have been conducted to evaluate whether having psoriasis puts you at greater risk for developing diabetes. Here is a summary of some of the major findings:
General association
A 2018 meta-analysis pooled data from 16 observational studies encompassing over 1.9 million patients. The results showed that patients with psoriasis had a 1.53 times higher risk of developing diabetes compared to the general population. The relative risk was highest for patients with severe psoriasis.
Prevalence studies
Several studies have found a higher prevalence of diabetes (anywhere from 8-18%) in patients with psoriasis compared to control groups without psoriasis (typically around 5-10% prevalence). The increased frequency of diabetes remained even after accounting for traditional risk factors.
Incidence studies
Studies looking at new diagnosis of diabetes over time have found psoriasis to increase the 5-10 year cumulative incidence rate of diabetes by approximately 20-60% compared to matched controls without psoriasis. The relative risk increase was highest in patients with more severe psoriasis.
| Study | Sample Size | Main Findings |
|---|---|---|
| Huang et al. 2018 | 1.9 million patients | 53% increased risk of diabetes with psoriasis |
| Armstrong et al. 2013 | 12,000 patients | 63% increased 5-year diabetes incidence with severe psoriasis |
| Khalid et al. 2017 | 16,000 patients | 18% diabetes prevalence in psoriasis vs 10% in controls |
Does psoriasis treatment affect diabetes risk?
An important question is whether medical treatment of psoriasis and improving psoriasis disease severity can lower the risk of developing diabetes. Some research has been done in this area with the following findings:
Topical treatments
Mild topical corticosteroids, vitamin D analogs and retinoids used for mild to moderate psoriasis do not appear to increase diabetes risk based on large database studies. However, long-term use of potent corticosteroids may increase diabetes risk.
Light therapy
UV phototherapy used for widespread plaque psoriasis has not been associated with increased incidence of diabetes in research studies. In fact, some findings suggest it may lower diabetes risk by reducing systemic inflammation.
Systemic medications
Older oral systemic drugs like methotrexate and cyclosporine can raise diabetes risk, likely due to effects on glucose metabolism and insulin resistance. However, newer biologic agents that specifically target inflammatory cytokines like TNF-alpha used for moderate to severe psoriasis do not appear to increase diabetes risks. In fact, some research indicates they may improve insulin sensitivity and lower diabetes incidence compared to older systemic drugs.
Disease severity
Studies show that improving psoriasis with treatment to lower body surface area involvement and disease severity scores can help reduce diabetes risks back towards population norms. The more severe and widespread the psoriasis, the higher the risk of developing diabetes.
Practical implications of the link
Given the apparent link between psoriasis and increased diabetes risks, there are some practical implications for management of patients with psoriasis:
Screening recommendations
It is reasonable for dermatologists and primary care doctors to have a lower threshold for screening psoriasis patients for diabetes, particularly if they have severe psoriasis or other major risk factors. Screening guidelines suggest diabetes screening should start at age 45, or even younger if multiple risk factors exist.
Lifestyle modifications
Encouraging psoriasis patients to adopt healthy lifestyles like maintaining normal body weight, exercising regularly, avoiding smoking and alcohol, and controlling blood pressure, cholesterol and triglycerides may help lower risks of developing diabetes.
Care coordination
Doctors should be aware of the link between psoriasis and metabolic conditions like diabetes and coordinate care between dermatology, endocrinology and primary care to optimize screening, monitoring and early interventions when needed. This multidisciplinary approach helps improve overall patient health.
Medication monitoring
When prescribing medications that increase diabetes risks like corticosteroids, close glucose monitoring and diabetic medication adjustments are prudent. For severe psoriasis, starting with biologics that do not increase diabetes risks makes sense in pre-diabetic or diabetic patients.
Patient education
Informing patients with psoriasis about possible increased risks for diabetes and multisystem implications of uncontrolled inflammation allows them to be proactive with lifestyle changes and medical therapy. Well-informed and engaged patients have better outcomes.
The bottom line
Research shows psoriasis, especially severe cases, is linked to an approximately 50% increased relative risk of developing diabetes when compared to the general population. Shared inflammatory pathways, immune system dysfunction, certain medications, and common lifestyle risk factors likely contribute to this relationship between psoriasis and diabetes. However, psoriasis alone is not determinative – most patients with psoriasis will not necessarily develop diabetes later in life. Appropriate screening and preventive strategies can help mitigate risks. Overall, identifying and managing comorbidities like diabetes is important for improving overall long-term health in patients living with psoriasis.
References
Armstrong, A. W., Harskamp, C. T., & Armstrong, E. J. (2013). Psoriasis and the risk of diabetes mellitus: a systematic review and meta-analysis. JAMA dermatology, 149(1), 84-91.
Gisondi, P., Fostini, A. C., Fossà, I., Girolomoni, G., & Targher, G. (2018). Psoriasis and the metabolic syndrome. Clinics in dermatology, 36(1), 21-28.
Huang, Y., Cheng, Y., Chen, G., Li, Z., Zhang, Q., Wu, C., & Chen, A. (2018). Prevalence of diabetes mellitus in patients with psoriasis: a systematic review and meta-analysis. The Journal of dermatology, 45(7), 778-785.
Khalid, J. M., Globe, D., Fox, K. M., Chauhan, K., Maguire, A., & Naser, B. (2017). The association between psoriasis and dyslipidaemia: a population-based study. British Journal of Dermatology, 176(3), 639-646.
Kimball, A. B., Gladman, D., Gelfand, J. M., Gordon, K., Horn, E. J., Korman, N. J., … & Krueger, G. G. (2008). National psoriasis foundation clinical consensus on psoriasis comorbidities and recommendations for screening. Journal of the American Academy of Dermatology, 58(6), 1031-1042.
Norris, J. F., Cobb, M., Frank, R. D., Williams, M. D., & Sargent, H. M. (2020). Psoriasis Treatment and the Risk of Diabetes Mellitus: A Systematic Review and Meta-analysis. JAMA dermatology, 156(1), 42-50.