Therapeutic Strategies for Microvascular Dysfunction in Type 1 Diabetes

The investigators will test the hypothesis that, in adults with type 1 diabetes (T1D), glucagon-like peptide-1 receptor agonism (GLP-1RA, i.e. dulaglutide) enhances insulin-mediated skeletal muscle microvascular perfusion via attenuating endothelial oxidative stress and thereby improving endothelial function.

Inclusion criteria: * History of type 1 diabetes, duration \> 5 years * Age 18-40 years * HbA1c \< 8.5% * BMI 19-34.9 kg/m2 * Using insulin for diabetes treatment only (multiple daily injections or insulin pump with or without sensor augmentation) * On stable regimen of non-diabetic medications for the last 6 months * All screening labs within normal limits or not clinically significant - English or Spanish speaking Exclusion criteria: * Pregnancy or currently breastfeeding * Smoking history within 6 months * History of microvascular (microalbuminuria, retinopathy, neuropathy) or macrovascular diabetes complications (coronary artery disease, stroke, peripheral vascular disease) as well as clinically significant cardiac arrhythmias or conduction disorders * Taking vasoactive medications (i.e. calcium channel blockers, angiotensin-converting enzyme or renin inhibitors, angiotensin-receptor blockers, nitrates, alpha-blockers). * Known hypersensitivity to perflutren (contained in Definity© contrast) * Screening O2 saturation \