Insulin Clamp Ancillary Study for Assessment of Insulin Resistance

Metformin Therapy for Overweight Adolescents With Type 1 Diabetes (T1D)--Insulin Clamp Ancillary Study for Assessment of Insulin Resistance

Insulin Clamp Ancillary study for Assessment of Insulin Resistance will be conducted as a sub-study to the main protocol, Metformin Therapy for Overweight Adolescents With Type 1 Diabetes (NCT01881828). The purpose of this ancillary study is to assess if metformin will improve tissue-specific insulin resistance (IR) in type 1 diabetes using a hyperinsulinemic euglycemic clamp; a 3-month randomized trial comparing metformin versus placebo in 12 to <20 year olds with BMI >85th percentile ( total daily insulin dose >0.7 units/kg, and HbA1c 7.0%-9.9%).

Inclusion Criteria:

1. Meets eligibility criteria of the main study, Metformin Therapy for Overweight Adolescents With Type 1 Diabetes (NCT01881828).

Exclusion Criteria:

1. Low hemoglobin or hematocrit as defined by each local institution's rules for insulin clamps or if no institutional requirements a Hematocrit <30% or hemoglobin <10 gm/dL