Type 2 diabetes risk in sarcoidosis patients untreated and treated with corticosteroids

Abstract

Background: The rate of type 2 diabetes mellitus (T2D) is increased in sarcoidosis patients but it is unknown if corticosteroid treatment plays a role. We investigated whether the T2D risk is higher in untreated and corticosteroid-treated sarcoidosis patients compared with the general population.

Methods: In this cohort study, individuals with two or more International Statistical Classification of Diseases and Related Health Problems (ICD) codes for sarcoidosis were identified from the Swedish National Patient Register (NPR) (n=5754). Corticosteroid dispensations within 3 months before or after the first sarcoidosis diagnosis were identified from the Swedish Prescribed Drug Register (PDR). General population comparators without sarcoidosis were matched to cases 10:1 on age, sex and region of residence (n=61 297). Incident T2D was identified using ICD codes (NPR) and antidiabetic drug dispensations (PDR). Follow-up was from the second sarcoidosis diagnosis/matching date until T2D, emigration, death or study end (December 2013). Cox regression models adjusted for age, sex, education, country of birth, healthcare regions and family history of diabetes were used to estimate hazard ratios (HRs). We used flexible parametric models to examine the T2D risk over time.

Results: 40% of sarcoidosis patients were treated with corticosteroid at diagnosis. The T2D rate was 7.7 per 1000 person-years in untreated sarcoidosis, 12.7 per 1000 person-years in corticosteroid-treated sarcoidosis and 5.5 per 1000 person-years in comparators. The HR for T2D was 1.4 (95% CI 1.2-1.8) associated with untreated sarcoidosis and 2.3 (95% CI 2.0-3.0) associated with corticosteroid-treated sarcoidosis. The T2D risk was highest for corticosteroid-treated sarcoidosis in the first 2 years after diagnosis.

Conclusions: Sarcoidosis is associated with an increased risk of T2D especially in older, male, corticosteroid-treated patients at diagnosis. Screening for T2D for these patients is advisable.

FIGURE 1

Flowchart of a) the study population starting with incident sarcoidosis patients with two or more inpatient or outpatient visits listing a sarcoidosis diagnosis living in Sweden between 2006 and 2013, and b) their comparators. ICD: International Statistical Classification of Diseases and Related Health Problems; T2D: type 2 diabetes mellitus; ATC: Anatomical Therapeutic Chemical; T1D: type 1 diabetes mellitus. ^#: see supplementary table S6.

FIGURE 2

Hazard ratio for type 2 diabetes mellitus comparing a) untreated sarcoidosis patients and b) corticosteroid-treated sarcoidosis patients with general population comparators without sarcoidosis. Hazard ratios were obtained from the flexible parametric models, and are adjusted for age, sex, education, region of residence, family history of diabetes and born in a Nordic country.

FIGURE 3

Cumulative incidence of type 2 diabetes mellitus comparing a, d) general population comparators with b, e) untreated sarcoidosis patients and c, f) corticosteroid-treated sarcoidosis patients in a–c) females and d–f) males. The cumulative incidences were obtained for an average person in the dataset using the flexible parametric survival model.