Effect of GLP-1 on Microvascular Insulin Responses in Type 1 Diabetes
Effect of GLP-1 on Microvascular Insulin Responses in Type 1 Diabetes
GLP-1 increases skeletal and cardiac microvascular perfusion and improves insulin's microvascular responses in human subjects with T1DM, leading to improved metabolic insulin responses, endothelial function, and increased muscle oxygenation
The proposed study will determine the effect of GLP-1 infusion on microvascular perfusion and microvascular insulin responses in both skeletal and cardiac muscle microvasculature in humans with T1DM. The investigators will study 20 participants with T1DM using a state-of-the-art technology, contrast enhanced ultrasound (CEU), to assess whether GLP-1 augments skeletal and cardiac microvascular blood flow (MBF) as a representation of microvascular perfusion, flow-mediated dilation (FMD) as a measurement of endothelial function, and augmentation index (AI) and pulse wave velocity (PWV) as surrogates for large vessel compliance. The investigators will use the combined CEU and euglycemic-hyperinsulinemic clamp approach to determine if microvascular and metabolic IR improves as a result.
Inclusion Criteria:
Exclusion Criteria:
1) Pregnancy or currently breastfeeding 2) Smoking history within 6 months 3) History of microvascular (microalbuminuria, retinopathy, neuropathy) or macrovascular diabetes complications (coronary artery disease, stroke, peripheral vascular disease) 4) Taking vasoactive medications (i.e. calcium channel blockers, angiotensin-converting enzyme or renin inhibitors, angiotensin-receptor blockers, nitrates, alpha-blockers) 5) OCP use within 3 months or 1 month if menses has subsequently occurred 6) Known hypersensitivity to perflutren (contained in Definity© contrast) 7) Screening O2 saturation<90% 8) Anemia (hemoglobin <12 g/dL in women, hemoglobin <13 g/dL in men) 9) Diabetic ketoacidosis (DKA) on presentation to screening visits or study admission days
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