The Prevalence of Autoimmune Diseases in Longstanding Diabetes: Results from the Canadian Study of Longevity in Type 1 Diabetes.

Objective: Type 1 diabetes (T1D) predisposes to higher lifetime autoimmune (AI) disease risk; the magnitude of this risk is not known with certainty. To approximate lifetime risk, we aimed to determine the prevalence of AI diseases in those exceeding 50 years T1D duration, as well as to explore sex-specific differences and associations with complications. Methods: Descriptive analysis of the Canadian Study of Longevity in T1D, a nationwide questionnaire study initiated in 2013 that recruited 374 T1D participants with duration >50 years. The questionnaire collected diabetes management variables, general medical history with a focus on AI disease, and diabetes-related complications. Clinical and laboratory data were obtained from primary care providers. The χ2-test and Student’s t-test were used for simple comparisons. Results: The 374 participants with longstanding T1D had median age of 66 [59, 71] years, T1D duration 53 [51, 58] years and HbA1c 7.5±1.0%. AI diseases were reported in 184/374 (49.3%). Thyroid disease was most prevalent, 154/374 (41.2%) reported thyroid disease or was prescribed thyroid hormone replacement therapy. Addison’s disease or prescribed glucocorticoid and mineralocorticoid therapy was reported in 5/374 (1.3%). Autoimmune polyendocrine syndrome type 2 (APS-2), defined by the presence of thyroid disease, Addison’s disease and T1D, was present in 3/374 (0.8%). We observed a sex-specific difference in AI disease prevalence (34.6 females vs. 14.8% in males; p<0.0001), driven by the difference in thyroid disease (29.5 females vs. 11.5% males, p<0.0001). No difference in HbA1c was observed (7.5±1.1 vs. 7.6±1.0%, p=0.62). There was a trend toward lower CAD prevalence among those with AI disease (12.1 vs. 16.9%, p=0.05). Conclusions: We estimate that in a population with longstanding T1D, the lifetime risk of AI disease approaches half, driven primarily by the presence of autoimmune thyroid disease, and with greater risk in females. Disclosure N. Cardinez: None. L. Lovblom: None. A. Orszag: None. D. Cherney: Other Relationship; Self; AbbVie Inc., AstraZeneca, Bayer AG, Boehringer Ingelheim International GmbH, Janssen Pharmaceuticals, Inc., Merck & Co., Inc., Mitsubishi Tanabe Pharma Corporation, Prometic Life Sciences Inc., Sanofi. B.A. Perkins: Advisory Panel; Self; Abbott, Boehringer Ingelheim International GmbH, Boehringer Ingelheim International GmbH, Insulet Corporation. Research Support; Self; Boehringer Ingelheim International GmbH. Other Relationship; Self; Abbott, Boehringer Ingelheim International GmbH, Lilly Diabetes, Medtronic, Novo Nordisk Inc., Sanofi. Funding JDRF (17-2013-312)