Psoriasis and the risk of diabetes mellitus: a systematic review and meta-analysis.

OBJECTIVE To compare the prevalence and incidence of type 2 diabetes mellitus between patients with psoriasis and those without psoriasis. DATA SOURCES MEDLINE, EMBASE, and Cochrane Database of Systematic Reviews between January 1, 1980, and January 1, 2012. STUDY SELECTION Observational (cohort, case-control, and cross-sectional) studies published in English that compared the prevalence or incidence of diabetes among patients with psoriasis with individuals serving as controls. DATA EXTRACTION Two independent investigators extracted the data. The quality of evidence was assessed using a 6-point scale. DATA SYNTHESIS Among 142 identified publications, 27 observational studies were included in the meta-analysis. Five of these studies assessed the incidence of diabetes in patients with psoriasis and were analyzed separately. Among studies assessing the prevalence, psoriasis was associated with an odds ratio (OR) of 1.59 (95% CI, 1.38-1.83) for diabetes. The pooled OR was 1.53 (95% CI, 1.16-2.04) for mild psoriasis and 1.97 (1.48-2.62) for severe psoriasis. Meta-regression of prespecified potential sources of heterogeneity revealed a nonsignificant difference (P= .10) of increased reported strength of association among studies that used medical record review (OR, 1.52 [95% CI, 1.31-1.77]) or patients' report of diabetes (2.79 [1.42-5.48]) compared with studies that used billing data (1.46 [1.01-2.09]). Among studies that assessed incidence, psoriasis was associated with a relative risk of 1.27 (95% CI, 1.16-1.40) for developing diabetes. CONCLUSIONS Psoriasis is associated with an increased prevalence and incidence of diabetes. The association of psoriasis with diabetes may be strongest among patients with severe psoriasis.