Contribution of Hyperinsulinemia vs. Hyperglycemia to Insulin Resistance in Type 1 Diabetes and Maturity Onset Diabetes of the Young, Type 2 (MODY2)

"Participants will undergo an 8-hour hyperinsulinemic, euglycemic clamp to quantify insulin sensitivity at whole-body and tissue-specific levels. The following hormones will be infused in the study:~* insulin (12 mU/m\^2/min \[3x basal\] for 150 minutes, then 40 mU/m\^2/min \[10x basal\] for 180 minutes)~* glucagon (0.65 ng/kg/min \[1x basal\] for 330 minutes)~* somatostatin (60 ng/kg/min) These infusions will maintain a basal glucagon level and an increased insulin level in the blood that will be equal between all 3 cohorts."

A variable infusion of 20% dextrose will be used to maintain plasma glucose within the euglycemic range throughout the hyperinsulinemic portion of the clamp. 6,6-H2 glucose will be infused at a low rate (0.033-0.22 µmol/kg/min) to determine glucose flux during the study.