Introduction: Numerous psychosocial interventions have been conducted in children and adolescents with type 1 diabetes, aiming to improve their self-management and autonomy acquisition. However, these tend to address family conflict and parental perspectives, and a scarce number of interventions explore the outcomes among preteens. This review examined the outcomes of psychosocial interventions for preteens with type 1 diabetes, as an under-researched field to date. Methods: A systematic literature review of intervention studies with randomized controlled trial design, targeting preteens with type 1 diabetes, was conducted. Six databases were searched for publication periods from 1995 to October 2019. Quality of the interventions according to the International Society for Pediatric and Adolescent Diabetes (ISPAD), as well as reporting and effect sizes, were assessed. Results: Twelve studies were selected, covering ten interventions. According to the topics identified, four of these interventions were categorized as self-care programmes, three as psychosocial programmes and three as mixed. All of the interventions, except for one, covered ≥50% of the ISPAD recommendations. Reporting adequacy was negative only in one intervention. Main outcomes were glycemic control and self-management, but effect sizes could only be calculated for half of the interventions with no overall significant effect. Conclusions: This review shows a lack of adequate psychosocial interventions targeting preteens with type 1 diabetes and actively involving them as participants. These intervention's educational programmes and methods should be standardized to guarantee successful results. New technologies and peer support implementation could be a promising pathway when designing these studies.