Physiologic Response to Glucagon at Varying Insulin Levels

We investigators have been working on the development of a closed loop (artificial endocrine
pancreas) insulin and glucagon infusion system since 2005 and are part of the Juvenile
Diabetes Research Foundation Artificial Pancreas Consortium. As part of our studies, we give
small doses of glucagon to prevent hypoglycemia. As we assessed the success and failure of
glucagon administration during these studies, we found the use of glucagon reduced the
frequency of hypoglycemia by about 75%. However, the fact that approximately 25% of
administrations of glucagon are ineffective remains a concern.

The primary question to be addressed by this study is, in the setting of low dose
subcutaneous glucagon administration, how do plasma glucagon and plasma insulin
quantitatively interact? In other words, as the rate of insulin administration is increased,
how much more glucagon is necessary to overcome the effect of insulin to prevent
hypoglycemia? This study is designed to address this question. Subjects will be brought in
to a Legacy Hospital for four 10 hour experiments on each of four separate days. On each
study day, there will be a continuous infusion of a different rate of IV Regular insulin in
order to achieve different steady state free insulin levels. At each insulin level, there
will be four subcutaneous glucagon doses given. Octreotide will be infused by IV at a
constant rate to suppress endogenous production of glucagon. A stable glucose isotope will
also be infused to allow for measurement of hepatic glucose production and glucose turnover.
Arterialized venous blood glucose will be measured by the HemoCue Glucose 201 Analyzer.

Inclusion Criteria:

- Diagnosis of type 1 diabetes mellitus for at least 1 year

- Male or female subjects 21 to 65 years of age

- Current use of an insulin pump

- Willingness to sign informed consent and HIPAA documents and follow all study
procedures

Exclusion Criteria:

- Pregnancy or Lactation: For women of childbearing potential: there is a requirement
for a negative urine pregnancy test and for agreement to use contraception during the
study and for at least 1 month after participating in the study

- Renal insufficiency (serum creatinine of 2.0 mg/dL or greater)

- Liver abnormalities: Serum ALT or AST equal to or greater than 3 times the upper
limit of normal; hepatic synthetic insufficiency as defined as a serum albumin of
less than 3.3 g/dL; or serum bilirubin of over 2

- Adrenal insufficiency

- Hematocrit of less than or equal to 34%

- A history of cerebrovascular disease or coronary artery disease regardless of the
time since occurrence

- Congestive heart failure, NYHA class III or IV

- Cardiac rhythm disturbance characterized by: 2nd or 3rd degree heart block,
bradycardia of less than 50 bpm (exception of bradycardia in an aerobic athlete),
tachycardia of greater than 100 bpm, or any arrhythmia judged by the investigator to
be exclusionary

- Any active infection

- Active foot ulceration

- Severe peripheral arterial disease characterized by ischemic rest pain or severe
claudication

- Active alcohol abuse, substance abuse, or severe mental illness (as judged by the
principal investigator)

- Active malignancy, except basal cell or squamous cell skin cancers

- Major surgical operation within 30 days prior to screening

- Seizure disorder

- Any concurrent illness, other than diabetes, that is not controlled by a stable
therapeutic regimen

- Chronic usage of any immunosuppressive medication

- Current administration of oral or parenteral corticosteroids

- Use of an investigational drug within 30 days prior to screening

- Bleeding disorder, treatment with warfarin, or platelet count below 50,000

- Allergy to glucagon

- Past history of pheochromocytoma or a family history of MEN 2, neurofibromatosis, or
von Hippel-Lindau disease

- Insulin resistance requiring more than 200 units per day