IMPORTANCE An association between the metabolic syndrome (MetS) and chronic inflammatory diseases, such as psoriasis or rheumatoid arthritis, has been suggested.Hidradenitis suppurativa (HS), a more localized chronic inflammation of the skin, has been speculated to have a similar association. Hidradenitis suppurativa is a substantial burden for the individual and a socioeconomic burden globally. Information about the burden of possible comorbidities is scarce.OBJECTIVE To investigate the possibility of an association between HS and MetS.DESIGN, SETTING, AND PARTICIPANTS Cross-sectional population- and hospital-based study of HS and MetS.We identified 32 patients with physician-verified HS from the outpatient clinic at the Department of Dermatology, Roskilde Hospital, and 326 patients with HS and 14 851 individuals without HS from the general population. Individuals with HS were younger,predominantly female, and more often smokers compared with the non-HS group.EXPOSURE Hidradenitis suppurativa.MAIN OUTCOMES AND MEASURES Metabolic syndrome and its components of diabetes mellitus, hypertension, dyslipidemia, and obesity.RESULTS When compared with the non-HS group, the odds ratios (ORs) for the hospital HS and population HS groups were 3.89 (95%CI, 1.90-7.98) and 2.08 (95%CI, 1.61-2.69),respectively, for MetS; 5.74 (95%CI, 1.91-17.24) and 2.44 (95%CI, 1.55-3.83), respectively, for diabetes mellitus; 6.38 (95%CI, 2.99-13.62) and 2.56 (95%CI, 2.00-3.28), respectively, for general obesity; and 3.62 (95%CI, 1.73-7.60) and 2.24 (95%CI, 1.78-2.82), respectively, for abdominal obesity. With regard to dyslipidemia, significant results were found for decreased levels of high-density lipoprotein cholesterol, with ORs of 2.97 (95%CI, 1.45-6.08) and 1.94(95%CI, 1.52-2.48) for the hospital HS and general population HS groups, respectively, when compared with the non-HS group. With regard to increased triglyceride levels, only the result for the population HS group compared with the non-HS group was significant, with an OR of1.49 (95%CI, 1.18-1.87). The OR for hypertension, which was only significant for the hospital HS group compared with the non-HS group, was 2.14 (95%CI, 1.01-4.53). Obesity and inflammation acted as possible confounders. The ORs were higher for the hospital HS group compared with the population HS group. The association between HS and MetS was not influenced by the degree of HS severity.CONCLUSIONS AND RELEVANCE As with more systemic inflammatory diseases, HS appears to be associated with MetS, indicating substantial comorbidities. Because this study is cross-sectional, causality remains to be explored.