Effect of Postprandial Hyperglycemia on Vasculature in Type 1 Diabetes and Healthy Adults

Inclusion Criteria: * Healthy with no chronic illness * Age 18-35 years * BMI ≤ 30 (wt kg/ht m2) * Normal screening labs or no clinically significant values * T1D participants must have T1D based on WHO diagnostic criteria for \> 1 year * A fasting plasma glucose level \>126 mg/dl (7.0 mmol/l) * A casual plasma glucose \>200 mg/dl (11.1 mmol/l) * In the absence of unequivocal hyperglycemia, the diagnosis must be confirmed on a subsequent day. * Subjects using sensor-augmented insulin pump therapy and/or artificial pancreas (closed loop system) will be included Exclusion Criteria: * • Smoking presently or have quit \< 2 years. * BP \>140/90 mmHg * BMI \>30 (wt kg/ht m2) * Pulse oximetry \<90% * Elevated LDL cholesterol \> 160 mg/dl * HbA1c ≥ 9 % * Use of statins, calcium channel blocker, ACE, ARB, nitrates, alpha-beta blockers or diuretics * History of cardiac, cerebrovascular, gastrointestinal, liver, renal decease or cancer * Presence of an intracardiac or intrapulmonary shunt (we will screen for this by auscultation during the physical exam by PI). * Retinopathy (beyond mild non proliferative retinopathy) * Urine albumin/creatinine ratio \> 300 mg per g * Pregnant or breastfeeding. * Known hypersensitivity to perflutren (contained in Definity