Abstract
AIMS/HYPOTHESIS: Sex differences are present in cardiovascular care and in outcomes among adults with type 1 diabetes mellitus, which typically commences in childhood. Whether sex influences care and outcomes in childhood is not known. This systematic review provides an overview of sex differences in children with type 1 diabetes, focusing on patient and disease characteristics, treatment, comorbidities and complications. METHODS: Literature in MEDLINE up to 15 June 2021 was searched, using the terms diabetes mellitus, sex characteristics, sex distribution, children and/or adolescents. All primary outcome studies on children with type 1 diabetes that mentioned a sex difference in outcome were included, with the exception of qualitative studies, case reports or case series. Studies not pertaining to the regular clinical care process and on incidence or prevalence only were excluded. Articles reporting sex differences were identified and assessed on quality and risk of bias using Joanna Briggs Institute critical appraisal tools. Narrative synthesis and an adapted Harvest plot were used to summarise evidence by category. RESULTS: A total of 8640 articles were identified, rendering 90 studies for review (n=643,217 individuals). Studies were of observational design and comprised cohort, cross-sectional and case-control studies. Most of the included studies showed a higher HbA(1c) in young female children both at diagnosis (seven studies, n=22,089) and during treatment (20 out of 21 studies, n=144,613), as well as a steeper HbA(1c) increase over time. Many studies observed a higher BMI (all ages, ten studies, n=89,700; adolescence, seven studies, n=33,153), a higher prevalence of being overweight or obese, and a higher prevalence of dyslipidaemia among the female sex. Hypoglycaemia and partial remission occurred more often in male participants, and ketoacidosis (at diagnosis, eight studies, n=3561) and hospitalisation was more often seen in female participants. Most of the findings showed that female participants used pump therapy more frequently (six studies, n=211,324) and needed higher insulin doses than male participants. Several comorbidities, such as thyroid disease and coeliac disease, appeared to be more common in female participants. All studies reported lower quality of life in female participants (15 studies, n=8722). Because the aim of this study was to identify sex differences, studies with neutral outcomes or minor differences may have been under-targeted. The observational designs of the included studies also limit conclusions on the causality between sex and clinical outcomes. CONCLUSIONS/INTERPRETATION: Sex disparities were observed throughout diabetes care in children with type 1 diabetes. Several outcomes appear worse in young female children, especially during adolescence. Focus on the cause and treatment of these differences may provide opportunities for better outcomes. REGISTRATION: This systematic review is registered in PROSPERO (CRD42020213640).