This supplementary appendix accompanies the article "The effect of early, comprehensive genomic testing on clinical care in neonatal diabetes: an international cohort study" published in The Lancet. The study highlights how genomic testing has transformed the diagnosis and management of neonatal diabetes, shifting from a trial-and-error approach to a more precise, targeted treatment strategy. The research involved a global cohort of 1016 neonatal diabetes patients, with genetic testing leading to more accurate diagnoses and tailored treatments. The study found that the median time from diagnosis to genetic testing referral has decreased over time, indicating improved access to and awareness of genetic testing. The number of referrals has also increased, reflecting a growing recognition of the importance of genetic testing in neonatal diabetes. The research identified 22 subtypes of neonatal diabetes, each associated with specific genetic mutations, and provided a detailed list of genetic causes in 840 patients. The study also describes the genetic testing pipeline, including both diagnostic and gene discovery pipelines. It outlines the methods used for genetic testing, including next-generation sequencing and Sanger sequencing, and the analysis of genetic variants. The research emphasizes the importance of comprehensive genomic testing in neonatal diabetes, leading to more effective clinical care and better patient outcomes. The study is supported by a range of references from previous research on neonatal diabetes and its genetic causes.This supplementary appendix accompanies the article "The effect of early, comprehensive genomic testing on clinical care in neonatal diabetes: an international cohort study" published in The Lancet. The study highlights how genomic testing has transformed the diagnosis and management of neonatal diabetes, shifting from a trial-and-error approach to a more precise, targeted treatment strategy. The research involved a global cohort of 1016 neonatal diabetes patients, with genetic testing leading to more accurate diagnoses and tailored treatments. The study found that the median time from diagnosis to genetic testing referral has decreased over time, indicating improved access to and awareness of genetic testing. The number of referrals has also increased, reflecting a growing recognition of the importance of genetic testing in neonatal diabetes. The research identified 22 subtypes of neonatal diabetes, each associated with specific genetic mutations, and provided a detailed list of genetic causes in 840 patients. The study also describes the genetic testing pipeline, including both diagnostic and gene discovery pipelines. It outlines the methods used for genetic testing, including next-generation sequencing and Sanger sequencing, and the analysis of genetic variants. The research emphasizes the importance of comprehensive genomic testing in neonatal diabetes, leading to more effective clinical care and better patient outcomes. The study is supported by a range of references from previous research on neonatal diabetes and its genetic causes.