| Outcome Measures: |
Primary: Differences in the gut microbiome in lean and obese youth with type 1 diabetes, cross sectional comparison of stool microbiome using metagenomic sequencing data, Baseline|Differences in the gut microbial metabolites in lean and obese youth with type 1 diabetes, The investigators will measure and compare the stool and serum short chain fatty acids using mass spectrometry, Baseline|Differences in the gut microbial metabolites in lean and obese youth with type 1 diabetes, The investigators will measure and compare the stool and serum secondary bile acids using mass spectrometry, Baseline|Changes in the gut microbiome in obese youth with type 1 diabetes in response to metformin, longitudinal comparison before and after taking metformin for 6 months, stool samples will be collected at baseline, 3 months and 6 months and sequenced for microbiome profile using metagenomic sequencing, Baseline, Month 3, and Month 6|Changes in the gut microbial metabolites in obese youth with type 1 in response to metformin, The investigators will measure and compare the stool and serum metabolites (short chain fatty acids and secondary bile acids) before, during and after 6 months of daily metformin therapy using mass spectrometry, Baseline, Month 3, and Month 6 | Secondary: Differences in measures of C-peptide as a measure of beta cell health in lean and obese T1D youth, The investigators will measure serum C-peptide to calculate a ratio of proinsulin to C-peptide as a marker of beta cell health. These measures will then be compared between the lean and obese T1D youth., Baseline|Differences in measures Proinsulin as a measure of beta cell health in lean and obese T1D youth, The investigators will measure serum proinsulin and calculate a ratio of proinsulin to C-peptide as a marker of beta cell health. These measures will then be compared between the lean and obese T1D youth., Baseline|Differences in measures of insulin sensitivity in lean and obese T1D youth, Insulin sensitivity will be assessed in individuals using the estimated insulin sensitivity score (eIS), which is based on waist circumference (cm), HbA1c (%) and triglycerides (mg/dl), Baseline|Changes in measures of C-peptide as a measure of beta cell health in obese T1D youth in response to metformin, Serum C-peptide will be used to calculate proinsulin to C-peptide ratio as a measure of beta cell health before and after metformin therapy, Baseline, Month 3, and Month 6|Changes in measures of proinsulin as a measure of beta cell health in obese T1D youth in response to metformin, Serum proinsulin will be used to calculate proinsulin to C-peptide ratio as a measure of beta cell health before and after metformin therapy, Baseline, Month 3, and Month 6|Changes in measures of insulin sensitivity in obese T1D youth in response to metformin, Estimated insulin sensitivity score will be used to assess response metformin therapy, Baseline, Month 3, and Month 6|Changes in measures of beta cell function using a timed mixed meal tolerance test, Participants in the metformin trial will undergo a standard 2-hour mixed meal tolerance test at baseline and after 6 months of oral metformin therapy, Baseline and Month 6
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