Introduction:The association between type 1 diabetes (T1D) and other auto-immune diseases is well known. However, a quantitative overview of all associated auto-immune diseases and their prevalence in T1D is lacking. Methods: We searched PubMed, Web of Science, EMBASE and Cochrane library in September 2018 to identify relevant articles about the prevalence of the following associated auto-immune diseases in T1D cohorts: auto-immune thyroid disease, celiac disease, gastric autoimmunity including pernicious anemia, vitiligo and adrenal gland insufficiency. A meta-analysis was performed to estimate pooled prevalence using a random-effects model. Furthermore, randomeffects meta-regression analysis was performed to assess the association between prevalence and mean age or diabetes duration. Results: One hundred eighty articles were eligible including a total of 293 889 type 1 diabetes patients. Hypothyroidism (65 studies) was prevalent in 9.8% (95% CI: 7.5-12.3) of patients. Meta-regression showed that for every 10-year age increase, hypothyroidism prevalence increased 4.6% (95% CI: 2.6-6.6, P < 0.000, 54 studies). Weighted prevalence of celiac disease was 4.5% (95% CI: 4.0-5.5, 87 studies). Gastric autoimmunity was found in 4.3% of patients (95% CI: 1.6-8.2, 8 studies) and vitiligo in 2.4% (95% CI: 1.2-3.9, 14 studies) of patients. The prevalence of adrenal insufficiency was 0.2% (95% CI: 0.0-0.4, 14 studies) and hyperthyroidism was found in 1.3 percent (95% CI: 0.9-1.8, 45 studies) of type 1 diabetes patients. For all analyses, statistical heterogeneity between studies was moderate to high. Conclusions: The prevalence of antibody-mediated auto-immune disease is high among type 1 diabetes patients. Especially hypothyroidism and celiac disease are frequently found.

overdiagnosis after 2012 remains yet largely unknown, the extent of overdiagnosis indicates an urgent need to closely monitor its evolution worldwide and the impact of recent guidelines.

Pancreatic islet transplantation is, together with whole pancreas transplantation, the only treatment that potentially obviates the need for insulin treatment in patients with type 1 diabetes mellitus and other forms of severe β cell deficiency. 1 β cell function posttransplant is an important indicator of the success of β cell replacement therapy and is used in the Igls criteria for assessment of β cell replacement therapy outcome. 2 β cell function is preferably measured by C-peptide, as endogenous insulin is partially cleared by the liver and suffers from cross-reactivity