Catherine Hu ^1,2,3 Milena Cioana ^1,2 Amandeep Saini ^1,2,3 Stephanie Ragganandan ^1,2,4 Jiawen Deng ^1,2 Ajantha Nadarajah ^1,2 Maggie Hou ^1,2 Yuan Qiu ^1,2,5 Sondra S. Chen ^1,2 Angelica Rivas ^1,2,5 Parm Pal Toor ^1,2,5 Laura Banfield ⁶ Lehana Thabane ^4,7,8,9 M. Constantine Samaan ^10,2,3,4*

• ¹ Department of Pediatrics, Faculty of Health Sciences, McMaster University, Hamilton, Canada
• ² Division of Pediatric Endocrinology, McMaster Children's Hospital, Hamilton, Ontario, Canada
• ³ McMaster University, Hamilton, Canada
• ⁴ Department of Health Research Methods, Evidence & Impact, Faculty of Health Sciences, McMaster University, Hamilton, Canada
• ⁵ Michael G. DeGroote School of Medicine, Faculty of Health Sciences, McMaster University, Hamilton, Canada
• ⁶ Health Sciences Library, McMaster University, Hamilton, Canada
• ⁷ Department of Anesthesia, Faculty of Health Sciences, McMaster University, Hamilton, Canada
• ⁸ St. Joseph's Healthcare, Hamilton, Canada
• ⁹ Biostatistics Unit, St Joseph's Healthcare, Hamilton, Canada
• ¹⁰ Department of Pediatrics, McMaster University, Hamilton, Canada

Introduction: Type 2 diabetes mellitus (T2DM) is rising in the pediatric population. One of the main associations of T2DM is non-alcoholic fatty liver disease (NAFLD), yet the full burden of NAFLD in T2DM is unclear. This study aimed to estimate the prevalence of NAFLD and Non-Alcoholic Steatohepatitis (NASH) in pediatric patients withT2DM . We also aimed to evaluate the association of sex, race/ethnicity, geographic location, NAFLD diagnostic methods, and glycemic control with NAFLD prevalence in this population. Method: Literature searches were conducted in in MEDLINE, Embase, CINAHL, Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, and Web of Science Core Collection from database inception to May 11 th , 2023. This systematic review and meta-analysis has been registered with the International Prospective Register of Systematic Reviews (PROSPERO; CRD42018091127). Observational studies with ≥ 10 participants reporting the prevalence of NAFLD in pediatric patients with T2DM were included. Four teams of two independent reviewers and one team with three reviewers screened articles and identified 26 papers fulfilling the eligibility criteria. Data extraction, risk of bias assessment, level of evidence assessment, and meta-analysis were performed. Results: The pooled prevalence of NAFLD was 33.82% (95% CI 24.23-44.11), and NASH prevalence was 0.28% (95% CI, 0.00-1.04). The Middle East had the highest NAFLD prevalence of 55.88% (95% CI 45.2-66.29) and Europe had the lowest prevalence of 22.46% (95% CI,). The prevalence of NAFLD was 24.17% (95% CI, 17.26-31.81) when only liver function tests were used, and rose to 48.85% (95% CI, 34.31-63.48) when combining the latter tests with ultrasound. Studies reporting solely on an ultrasound-based diagnosis of NAFLD reported a prevalence of 40.61% (95% CI, 17.25-66.42) compared to 54.72% (95% CI,) in studies using MRI/MRS. No differences in prevalence were noted based on glycemic control. Heterogeneity was high among studies. Conclusion: NAFLD is a common comorbidity in pediatric T2DM . Further understanding of the optimal screening approaches for NAFLD diagnosis and evaluating its determinants and natural history is warranted to help establish its exact burden and to aid the development of targeted screening, management, and prevention strategies of NAFLD in T2DM patients.