Aims/hypothesis This register-based study aimed to describe autoimmune comorbidity in children and young adults from type 1 diabetes onset, and to investigate whether such comorbidity was associated with a difference in HbA1c or mortality risk compared with children/young adults with type 1 diabetes without autoimmune comorbidity. Methods A total of 15,188 individuals from the Swedish National Diabetes Register, registered with type 1 diabetes before 18 years of age between 2000 and 2019, were included. Five randomly selected control individuals from the Swedish population (Statistics Sweden) were matched to each individual with type 1 diabetes (n=74,210 [346 individuals with type 1 diabetes were not found in the Statistics Sweden register at the date of type 1 diabetes diagnosis, so could not be matched to control individuals]). The National Patient Register was used to attain ICD-10 codes on autoimmune diseases and the Cause of Death Register was used to identify deceased individuals. Results In the total type 1 diabetes cohort, mean +/- SD age at onset of type 1 diabetes was 9.5 +/- 4.4 years and mean disease duration at end of follow-up was 8.8 +/- 5.7 years. Of the individuals with type 1 diabetes, 19.2% were diagnosed with at least one autoimmune disease vs 4.0% of the control group. The HRs for comorbidities within 19 years from onset of type 1 diabetes were 11.6 (95% CI 10.6, 12.6) for coeliac disease, 10.6 (95% CI 9.6, 11.8) for thyroid disease, 1.3 (95% CI 1.1, 1.6) for psoriasis, 4.1 (95% CI 3.2, 5.3) for vitiligo, 1.7 (95% CI 1.4, 2.2) for rheumatic joint disease, 1.0 (95% CI 0.8, 1.3) for inflammatory bowel disease, 1.0 (95% CI 0.7, 1.2) for systemic connective tissue disorder, 1.4 (95% CI 1.1, 1.9) for uveitis, 18.3 (95% CI 8.4, 40.0) for Addison's disease, 1.8 (95% CI 0.9, 3.6) for multiple sclerosis, 3.7 (95% CI 1.6, 8.7) for inflammatory liver disease and 19.6 (95% CI 4.2, 92.3) for atrophic gastritis. Autoimmune disease in addition to type 1 diabetes had no statistically significant effect on HbA1c or mortality risk. Conclusions/interpretation To our knowledge, this is the first comprehensive study where young individuals with type 1 diabetes were followed regarding development of a wide spectrum of autoimmune diseases, from onset of type 1 diabetes. In this nationwide and population-based study, there was already a high prevalence of autoimmune diseases in childhood, especially coeliac and thyroid disease. The presence of autoimmune comorbidity did not have a statistically significant effect on metabolic control or mortality risk.

Aims: The aim of the study was to estimate the effect of household relative poverty on the risk of diabetic ketoacidosis at diagnosis of children with type 1 diabetes using an international standard measurement of relative poverty.Methods: A national population-based retrospective study was conducted. The Swedish National Diabetes Register (NDR) was linked with data from Sweden's public statistical agency (Statistics Sweden). Children who were diagnosed with new-onset type 1 diabetes in the period of 2014-2019 were common identifiers. The definition of diabetic ketoacidosis was venous pH <7.30 or a serum bicarbonate level <18 mmol/L. The exposure variable was defined according to the standard definition of the persistent at-risk-of-poverty rate used by the statistical office of the European Union (Eurostat) and several other European public statistical agencies. Univariate and multi-variable analyses were used to calculate the effect of relative poverty on the risk of diabetic ketoacidosis.Results: Children from households with relative poverty had a 41% higher risk of diabetic ketoacidosis (1.41, CI 1.12-1.77, p = 0.004) and more than double the risk of severe diabetic ketoacidosis (pH <7.10) (RR 2.10, CI 1.35-3.25, p = 0.001), as compared to children from households without relative poverty.Conclusions: Relative poverty significantly increases the risk of diabetic ketoacidosis at onset of type 1 diabetes in children, even in a high-income country with publicly reimbursed health care.

Aim/hypothesis Environmental factors are believed to contribute to the risk of developing type 1 diabetes. The aim of this study was to investigate how size for gestational age affects the risk of developing childhood type 1 diabetes.

Methods Using the Swedish paediatric diabetes quality register and the Swedish medical birth register, children with type 1 diabetes diagnosed between 2000 and 2012 (n = 9376) were matched with four control children (n = 37,504). Small for gestational age (SGA) and large for gestational age (LGA) were defined according to Swedish national standards. Data were initially analysed using Pearsons chi(2) and thereafter by single and multiple logistic regression models.

Results An equal proportion of children were born appropriate for gestational age, but children with type 1 diabetes were more often born LGA and less often born SGA than control children (4.7% vs 3.5% and 2.0% vs 2.6%, respectively, p < 0.001). In the multiple logistic regression analysis, being born LGA increased (adjusted OR 1.16 [95% CI 1.02, 1.32]) and SGA decreased (adjusted OR 0.76 [95% CI 0.63, 0.92]) the risk for type 1 diabetes, regardless of maternal BMI and diabetes.

Conclusions/interpretation Size for gestational age of Swedish children affects the risk of type 1 diabetes, with increased risk if the child is born LGA and decreased risk if the child is born SGA. Being born LGA is an independent risk factor for type 1 diabetes irrespective of maternal BMI and diabetes. Thus, reducing the risk for a child being born LGA might to some extent reduce the risk for type 1 diabetes.

Objectives To identify differences and similarities in HbA1c levels and patterns regarding age and gender in eight high-income countries. Subjects 66 071 children and adolescents below18 years of age with type 1 diabetes for at least 3 months and at least one HbA1c measurement during the study period. Methods Pediatric Diabetes Quality Registry data from Austria, Denmark, England, Germany, Norway, Sweden, the United States, and Wales were collected between 2013 and 2014. HbA1c, gender, age, and duration were used in the analysis. Results Distribution of gender and age groups was similar in the eight participating countries. The mean HbA1c varied from 60 to 73 mmol/mol (7.6%-8.8%) between the countries. The increase in HbA1c between the youngest (0-9 years) to the oldest (15-17 years) age group was close to 8 mmol/mol (0.7%) in all countries (P < .001). Females had a 1 mmol/mol (0.1%) higher mean HbA1c than boys (P < .001) in seven out of eight countries. Conclusions In spite of large differences in the mean HbA1c between countries, a remarkable similarity in the increase of HbA1c from childhood to adolescence was found.