RADIANT has three distinct stages.~Stage 1:~Stage 1 participants will complete a consent form and a questionnaire to determine the potential for having atypical forms of diabetes. Participants identified as potentially atypical based on questionnaire responses will be asked to provide a blood sample to test for islet autoantibodies and complete additional questionnaires.~The RADIANT Adjudication Committee, which is comprised of a team of experts in diabetes, will assess the data collected in Stage 1 and select and prioritize participants to proceed to Stage 2 and 3 for Whole Genome Sequencing (WGS) and other testing.~Stage 2:~Stage 2 of the study includes genetic screening for known forms of monogenic diabetes. Participants will consent for this stage of the study, complete a family history questionnaire, and have blood collected for DNA and RNA extraction, storage, and analysis. WGS will be performed on all DNA samples. If no pathogenic/likely pathogenic variant in a known monogenic diabetes gene that is thought to explain the participant's diabetes is identified by WGS, RNA Sequencing will be performed at Baylor College of Medicine.~Stage 3:~Stage 3 of the study includes deeper phenotyping. All participants who proceed to Stage 3 will visit a study clinic to consent and complete Stage 3 Standard procedures which include: an Oral Glucose Tolerance Test (OGTT), additional blood collection, a detailed physical exam, and additional questionnaires.~Discovery Team Review:~The work of the Discovery Team is expected to be an iterative process analyzing all data collected up to this point in the study to understand the significance of novel variants. In some instances, the Discovery Team may determine that enrollment of the Proband's family members is necessary. Family members with suspected atypical diabetes will follow the same study procedures as described above. Affected and unaffected family members may also be enrolled for Sanger Sequencing. The Discovery Team may also recommend additional optional procedures to better characterize the participant's form of diabetes.
RADIANT is a network of 14 clinical sites and several laboratories dedicated to the study of atypical diabetes.~The objective of this study is to define new forms of diabetes and the unique mechanisms underlying these forms of atypical diabetes. The specific aims are to:~Identify and enroll individuals and families with undiagnosed rare and atypical forms of diabetes.~Determine the etiologic basis of the metabolic disorder among individuals and families with novel forms of rare and atypical diabetes.~Understand the pathophysiology of individuals and families with novel forms of rare and atypical forms of diabetes.