Diabetes incidence in psoriatic arthritis, psoriasis and rheumatoid arthritis: a UK population-based cohort study

The objective of this study was to evaluate the incidence of diabetes among patients with PsA and RA in the general population.

We conducted a cohort study using an electronic medical records database representative of the UK general population (1986-2010). We estimated hazard ratios (HRs) for incident diabetes in PsA, psoriasis and RA cohorts compared with age- and sex-matched comparison cohorts without the corresponding conditions, adjusting for BMI, smoking, alcohol use, co-morbidities and glucocorticoids at baseline.

Cohorts included 4196 persons with PsA, 59 281 with psoriasis and 11 158 with RA, with mean follow-up times of 5.9, 5.8 and 5.5 years, respectively. Incidence rates for diabetes were 7.3, 6.4 and 6.3 cases per 1000 person-years among individuals with PsA, psoriasis and RA, respectively. Age- and sex-matched HRs for diabetes were 1.72 (95% CI 1.46, 2.02) in PsA, 1.39 (95% CI 1.32, 1.45) in psoriasis and 1.12 (95% CI 1.01, 1.25) in RA. After adjustment for BMI, smoking and alcohol, the HRs were attenuated substantially (1.43, 1.24 and 1.00, respectively). With further adjustment for baseline glucocorticoid use and co-morbidities, the HRs were 1.33 (1.09, 1.61) in PsA, 1.21 (1.15, 1.27) in psoriasis and 0.94 (0.84, 1.06) in RA.

This general population study suggests an increased incidence of diabetes in PsA and RA, which is substantially explained by obesity and lifestyle factors. These findings support the importance of managing such factors in PsA and RA patients.