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

The investigator will compare 17 T1D and 17 age-, sex-, and BMI-matched healthy controls (18-35 yrs) measuring pulse wave velocity (PWV), flow-mediated dilation (FMD) and myocardial perfusion (contrast enhanced ultrasound [CEU]) before and 2 hours after ingesting a mixed meal (40% of each subject's daily estimated caloric need, with 50%, 30%, 20% from carbohydrates, fat and protein, respectively).

T1D participants will have 2 study admissions:

A) injection of insulin 15 minutes before ingesting a mixed meal. B) injection of insulin 15 min after ingesting a mixed meal.

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