Usual Care includes the multidisciplinary health care, education and supports that are routinely available to Nemours families of youth with T1D. This includes clinic visits approximately every 3 months with a pediatric endocrinologist or advanced practice nurse, with referrals to a certified diabetes educator, dietitian, social worker or psychologist as deemed clinically necessary by that HCP.

Transdisciplinary Care includes all elements of Usual Care, but quarterly T1D visits are co-managed by an APN, RD and a Psychologist who provide care to the adolescent and parent(s) as a team during each visit. A central TC feature is active incorporation of evidence-based psychosocial care for T1D into visits including motivational interviewing techniques, systematic problem solving, and the facilitation of family communication to address each family's self-identified T1D challenges. TC visits will include interaction with all three team members jointly, with subsequent interaction between the parent/youth or both with a subset of this team as decided by family and team consensus during the visit.

TC is being compared to UC using baseline and 12 month data, controlling for patient age, sex, and race/ethnicity. The interaction between condition and time is used to examine the treatment effect. Missing data were not imputed.

Usual Care includes the multidisciplinary health care, education and supports that are routinely available to Nemours families of youth with T1D. This includes clinic visits approximately every 3 months with a pediatric endocrinologist or advanced practice nurse, with referrals to a certified diabetes educator, dietitian, social worker or psychologist as deemed clinically necessary by that HCP.

Transdisciplinary Care includes all elements of Usual Care, but quarterly T1D visits are co-managed by an APN, RD and a Psychologist who provide care to the adolescent and parent(s) as a team during each visit. A central TC feature is active incorporation of evidence-based psychosocial care for T1D into visits including motivational interviewing techniques, systematic problem solving, and the facilitation of family communication to address each family's self-identified T1D challenges. TC visits will include interaction with all three team members jointly, with subsequent interaction between the parent/youth or both with a subset of this team as decided by family and team consensus during the visit.

TC is being compared to UC using baseline and 12 month data and controlling for patient age, sex, and race/ethnicity. The interaction between condition and time is used to evaluate the treatment effect. Missing data are not imputed.

Usual Care participants receive the same excellent multidisciplinary care they would receive at the same center were they not enrolled in the trial. In clinic visits scheduled at approximately 3-month intervals, they will see subspecialty board certified or eligible pediatric endocrinologists, supplemented as needed with involvement of certified diabetes educators, dietitians, social workers or psychologists. HbA1c target is < 7.5% with no severe hypoglycemia and acceptable quality of life. About half are expected to be on insulin pumps and carbohydrate counting, while the great majority of others are following basal-bolus multiple daily injection regimens, also based on carbohydrate counting. A rising proportion of patients use continuous glucose monitors and this trend is likely to accelerate during the study.

In addition to all elements of Usual Care, TC-IP participants will have follow-up clinic visits in-person or by telehealth at approximately 3 month intervals during the study that will consist of simultaneous involvement of an advanced practice nurse, dietitian and psychologist who will see the parent and adolescent together. TC team members will have passed a competency exam following completion of a training course on each of the TC team professional disciplines.

Transdisciplinary Care-In Person & Telehealth: TC participants will receive all elements of the Usual Care intervention but they will do so in the context of face to face or telehealth delivery of TC follow-up visits with simultaneous involvement of an advanced practice nurse, dietitian and psychologist at each visit.

This analysis included baseline and 12-month data. The interaction of condition (TC or UC) and time was used to examine the treatment effect. Child sex, age, and race/ethnicity were covariates. Missing data were not imputed.

Usual Care participants receive the same excellent multidisciplinary care they would receive at the same center were they not enrolled in the trial. In clinic visits scheduled at approximately 3-month intervals, they will see subspecialty board certified or eligible pediatric endocrinologists, supplemented as needed with involvement of certified diabetes educators, dietitians, social workers or psychologists. HbA1c target is < 7.5% with no severe hypoglycemia and acceptable quality of life. About half are expected to be on insulin pumps and carbohydrate counting, while the great majority of others are following basal-bolus multiple daily injection regimens, also based on carbohydrate counting. A rising proportion of patients use continuous glucose monitors and this trend is likely to accelerate during the study.

In addition to all elements of Usual Care, TC-IP participants will have follow-up clinic visits in-person or by telehealth at approximately 3 month intervals during the study that will consist of simultaneous involvement of an advanced practice nurse, dietitian and psychologist who will see the parent and adolescent together. TC team members will have passed a competency exam following completion of a training course on each of the TC team professional disciplines.

Transdisciplinary Care-In Person & Telehealth: TC participants will receive all elements of the Usual Care intervention but they will do so in the context of face to face or telehealth delivery of TC follow-up visits with simultaneous involvement of an advanced practice nurse, dietitian and psychologist at each visit.

This analysis uses baseline and 12 month data. The interaction of condition and time is used to evaluate the treatment effect. Child sex, age, and race/ethnicity were used as covariates. Missing data were not imputed.

Usual Care participants receive the same excellent multidisciplinary care they would receive at the same center were they not enrolled in the trial. In clinic visits scheduled at approximately 3-month intervals, they will see subspecialty board certified or eligible pediatric endocrinologists, supplemented as needed with involvement of certified diabetes educators, dietitians, social workers or psychologists. HbA1c target is < 7.5% with no severe hypoglycemia and acceptable quality of life. About half are expected to be on insulin pumps and carbohydrate counting, while the great majority of others are following basal-bolus multiple daily injection regimens, also based on carbohydrate counting. A rising proportion of patients use continuous glucose monitors and this trend is likely to accelerate during the study.

In addition to all elements of Usual Care, TC-IP participants will have follow-up clinic visits in-person or by telehealth at approximately 3 month intervals during the study that will consist of simultaneous involvement of an advanced practice nurse, dietitian and psychologist who will see the parent and adolescent together. TC team members will have passed a competency exam following completion of a training course on each of the TC team professional disciplines.

Transdisciplinary Care-In Person & Telehealth: TC participants will receive all elements of the Usual Care intervention but they will do so in the context of face to face or telehealth delivery of TC follow-up visits with simultaneous involvement of an advanced practice nurse, dietitian and psychologist at each visit.

This analysis included baseline and 12 month data. The condition by time interaction was used to evaluate the treatment effect. Child age, sex, and race/ethnicity were included as covariates. Missing data were not imputed.

Usual Care participants receive the same excellent multidisciplinary care they would receive at the same center were they not enrolled in the trial. In clinic visits scheduled at approximately 3-month intervals, they will see subspecialty board certified or eligible pediatric endocrinologists, supplemented as needed with involvement of certified diabetes educators, dietitians, social workers or psychologists. HbA1c target is < 7.5% with no severe hypoglycemia and acceptable quality of life. About half are expected to be on insulin pumps and carbohydrate counting, while the great majority of others are following basal-bolus multiple daily injection regimens, also based on carbohydrate counting. A rising proportion of patients use continuous glucose monitors and this trend is likely to accelerate during the study.

In addition to all elements of Usual Care, TC-IP participants will have follow-up clinic visits in-person or by telehealth at approximately 3 month intervals during the study that will consist of simultaneous involvement of an advanced practice nurse, dietitian and psychologist who will see the parent and adolescent together. TC team members will have passed a competency exam following completion of a training course on each of the TC team professional disciplines.

Transdisciplinary Care-In Person & Telehealth: TC participants will receive all elements of the Usual Care intervention but they will do so in the context of face to face or telehealth delivery of TC follow-up visits with simultaneous involvement of an advanced practice nurse, dietitian and psychologist at each visit.

This analysis uses baseline and 12-month data. The interaction between condition and time is used to evaluate the treatment effect. Child age, sex, and race/ethnicity were covariates. Missing data were not imputed.