This study investigates the gut microbiome in youths with Type 1 Diabetes (T1D) based on their body mass index. Type 1 Diabetes is an autoimmune condition where the body's immune system attacks insulin-producing cells, leading to a need for insulin therapy. The study aims to find out if the gut microbiome, which is the community of microorganisms living in the intestines, is different in obese versus lean youths with T1D compared to healthy youths.

Participants will undergo procedures to analyze their gut microbiome and measure levels of beta-cell stress or death. Beta-cells are cells in the pancreas that make insulin. The study will look at whether changes in the microbiome are linked to how much stress or death these cells experience.

• Who can participate: Youths aged 11-18 years with Type 1 Diabetes at the time of diagnosis and enrollment can participate. Participants must be either obese or lean and should not have Type 2 Diabetes, ongoing infections, or a history of certain medical conditions or treatments.
• Study details: Participants will provide samples for analysis of their gut microbiome. The study will compare these samples to see if there are differences based on body weight and diabetic status. A placebo is not used in this study.