Feasibility Study of Closed Loop Control in Type 1 Diabetes Using Heart Rate Monitoring as an Exercise Marker

The combination of the Control to Range system and the cell phone is called the "Artificial Pancreas (AP) Platform". The purpose of this study is to see if this investigational technology can help control blood sugar in people with type 1 diabetes mellitus on insulin pump therapy can be successfully used and supervised in a hospital setting. This study is also being done to see if giving information about heart rate to the Closed-to-Range System can reduce hypoglycemia as it relates to exercise. Subjects will exercise on an exercise bike in the clinical research unit. During one exercise testing session, the Closed-to-Range System will receive information about your heart rate (Experimental Condition). During the other exercise testing session, the Control to Range System will not receive information about your heart rate (Control Condition). This part of the study is being done to see whether heart rate information helps the Closed-to-Range System reduce the occurrences of exercise-related hypoglycemia.

The Closed-to-Range system has two parts (modules) that can work together or separately.

A. The Safety Supervision Module (SSM) helps to prevent low blood sugars. It can reduce the amount of basal insulin that the pump is delivering and alert you if carbohydrates are needed to help prevent a low blood sugar. This module will be active at all times during the operation of the Closed-to-Range System.

B. The Hyperglycemia Mitigation Module (HMM) helps to prevent high blood sugars. It can instruct the insulin pump to deliver small boluses to help prevent high blood sugar. It can also help warn you of a possible pump problem if the blood sugar level is not responding to the insulin as it should.

The Closed-to-Range System works with the insulin pump and continuous glucose monitor to help keep the blood sugar in a desired range (80-180 mg/dL) during the day and help avoid hypoglycemia during the night.

Inclusion criteria

• ≥21 and <65 years old with clinical diagnosis of Type 1 Diabetes Mellitus for at least 1 year.
• Criteria for documented hyperglycemia (at least 1 criterion must be met):

• Fasting glucose ≥126 mg/dL - confirmed
• Two-hour Oral Glucose Tolerance Test (OGTT) glucose ≥200 mg/dL - confirmed
• HbA1c ≥6.5% documented - confirmed
• Random glucose ≥200 mg/dL with symptoms
• No data at diagnosis is available but the participant has a convincing history of hyperglycemia consistent with diabetes.

Criteria for requiring insulin at diagnosis (at least 1 criterion must be met):

• Participant required insulin at diagnosis and continually thereafter
• Participant did not start insulin at diagnosis but upon investigator review likely needed insulin (significant hyperglycemia that did not respond to oral agents) and did require insulin eventually and used continually
• Participant did not start insulin at diagnosis but continued to be hyperglycemic, had positive islet cell antibodies - consistent with latent autoimmune diabetes (LADA) in adults and did require insulin eventually and used continually.

Criteria for Type 1 Diabetes Mellitus (at least 1 criterion must be met)

• Documented low or absent C-peptide level.
• Documented presence of Islet Cell Cytoplasmic Autoantibodies (ICA) or Glutamic Acid Decarboxylase (GAD65) antibodies.
• Use of an insulin pump to treat his/her diabetes for at least 6 months
• Actively using a bolus calculator with the current insulin pump with pre-defined parameters for carbohydrate (CHO) ratio, insulin sensitivity factor (ISF), and target glucose
• HbA1c between 5.0% and 10.5% as measured with DCA2000 or equivalent device
• Not currently known to be pregnant, breast feeding, or intending to become pregnant (females)
• Demonstration of proper mental status and cognition for the study.
• Willingness to avoid consumption of acetaminophen-containing products during the study interventions involving continuous glucose monitor use.
• If on antihypertensive, thyroid, anti-depressant or lipid lowering medication, have stability on the medication for at least 2 months prior to enrollment in the study.

Exclusion criteria

• Clinical diagnosis of Type 2 Diabetes Mellitus
• Diabetic ketoacidosis within the 6 months prior to enrollment
• Severe hypoglycemia resulting in seizure or loss of consciousness in the 3 months prior to enrollment
• Pregnancy, breast feeding, or intention of becoming pregnant
• Uncontrolled arterial hypertension (diastolic blood pressure >90 mmHg and/or systolic blood pressure >160 mmHg)
• Hematocrit <36% (females); <38% (males)
• Uncontrolled thyroid disease or thyroid replacement as determined by a thyroid-stimulating hormone (TSH) out of the UVa reference range.
• Impaired hepatic function measured as alanine aminotransferase or aspartate aminotransferase >2 times the upper limit of normal
• Impaired renal function measured as creatinine >1.5 mg/dL
• Conditions which may increase the risk of hypoglycemia such as known coronary artery disease (e.g. history of myocardial infarction, acute coronary syndrome, therapeutic coronary intervention, coronary bypass or stenting procedure, stable or unstable angina, episode of chest pain of cardiac etiology with documented EKG changes, or positive stress test or catheterization with coronary blockages >50%), congestive heart failure, history of cerebrovascular event, seizure disorder, syncope, adrenal insufficiency, neurologic disease or atrial fibrillation
• Additional conditions which may inhibit the ability to perform exercise on a stationary bike (e.g. injury to or immobility of limbs, neuromuscular disease, exercise-induced asthma requiring inhaler use within the last 12 months or clinically impaired pulmonary function)
• Use of a medication that significantly lowers heart rate (beta blockers, reserpine, guanethidine, methyldopa, clonidine, cimetidine, digitalis, calcium channel blockers, amiodarone, antiarrythmic drugs, or lithium)
• History of a systemic or deep tissue infection with methicillin-resistant staph aureus or Candida albicans
• Use of a device that may pose electromagnetic compatibility issues and/or radiofrequency interference with the continuous glucose monitor (CGM) (implantable cardioverter-defibrillator, electronic pacemaker, neurostimulator, intrathecal pump, and cochlear implants)
• Medical condition requiring use of an acetaminophen-containing medication that cannot be withheld for the study admissions.
• Psychiatric disorders that would interfere with study tasks (e.g. inpatient psychiatric treatment within 6 months prior to enrollment, uncontrolled anxiety or panic disorder)
• Mental incapacity, unwillingness or language barriers precluding adequate understanding or cooperation
• Current or recent alcohol or drug abuse by patient history
• Medical conditions that would make operating a CGM, cell phone or insulin pump difficult (e.g. blindness, severe arthritis, immobility)
• Any skin condition that prevents sensor or pump placement on the abdomen or arm (e.g. bad sunburn, pre-existing dermatitis, intertrigo, psoriasis, extensive scarring, cellulitis)
• Known microvascular (diabetic) complications (other than diabetic non-proliferative retinopathy), such as history of laser coagulation, proliferative diabetic retinopathy, known diabetic nephropathy (other than microalbuminuria with normal creatinine) or neuropathy requiring treatment
• Active gastroparesis requiring current medical therapy
• If on antihypertensive, thyroid, anti-depressant or lipid lowering medication, lack of stability on the medication for the past 2 months prior to enrollment in the study
• Known bleeding diathesis or dyscrasia
• Known allergy to medical adhesives, components of the insulin pump insertion set or continuous glucose monitor sensor
• Anticoagulant therapy other than aspirin
• Oral steroids
• Active enrollment in another clinical trial
• Unwillingness to avoid acetaminophen while the continuous glucose monitor is in use.
• Unwillingness to withhold dietary supplements two weeks prior to admission and for the duration of the study participation.
• Subjects with basal rates less than 0.05.

Restrictions on use of other drugs or treatments

• Pramlintide, liraglutide and exenatide will be held for the duration of the study intervention.
• Oral steroids are excluded
• Anticoagulant therapy other than aspirin is excluded
• Acetaminophen will not be allowed while the continuous glucose monitor is in use
• Dietary supplements will be withheld two weeks prior to admission and for the duration of study participation
• Beta blockers, reserpine, guanethidine, methyldopa, clonidine, cimetidine, digitalis, calcium channel blockers, amiodarone, antiarrythmic drugs, and lithium are excluded