This study employs a cross-sectional design to profile the gut microbiome and urine metabolome in overweight/obese children with type 1 diabetes (T1D).

The investigators will obtain stool and urine samples from subjects aged 7-17 years in 4 groups:

• Group 1: Obese or overweight children within 3 years of diagnosis of T1D
• Group 2: Normal weight children within 3 years of diagnosis of T1D
• Group 3: Obese or overweight children without T1D
• Group 4: Normal weight children without T1D

Type 1 diabetes will be defined according to American Diabetes Association criteria along with the presence of pancreatic autoantibodies (GAD65, ICA512, or insulin autoantibodies). Obese and overweight status will be defined by BMI >85th percentile for age and gender according to CDC criteria.

All subjects will provide one-time stool and first morning urine sample. Overweight or obese subjects will additionally have a point of care blood glucose and hemoglobin A1c measurement to ensure that they do not have diabetes.

The investigators will perform 16S rRNA sequencing of stool bacteria and mass spectrometry measurement of urine metabolites.

Inclusion Criteria:

• Age 7 to 17 years
• Diagnosis of diabetes will be defined by current American Diabetes Association criteria ° (fasting glucose > 126 mg/dl, 2 hour OGTT glucose > 200 mg/dl; random glucose > 200 with symptoms of hyperglycemia; or HbA1c > 6.5%)
• Diabetes duration < 3 years
• Presence of pancreatic autoimmunity (GAD65, ICA512, or insulin autoantibody positivity)
• Adult caregiver willing to actively support study participation
• Signed parental informed consent form and minor child informed assent form

Exclusion Criteria:

• Other significant organ system illness or condition (including psychiatric or developmental disorder) that, in the opinion of the investigator, would prevent participation

Children aged 7-17 years with/without T1DM and with/without obese/overweight status in San Diego, California