A Clinical Study of the Performance of a Glucose Blinding Protein-Based Continuous Glucose Monitor (GBP CGM)

Development of accurate continuous glucose monitoring devices is critically important for the maintenance of strict glycemic control without increasing the risk for hypoglycemia and for the successful implementation of an artificial pancreas. Glucose binding protein-based (GBP) continuous glucose monitors offer several potential advantages over commercially available glucose oxidase based sensors. Unlike glucose oxidase based sensors, GBP sensors do not require establishment of an equilibrium reduction/oxidation reaction and are not as susceptible to interference from other compounds because they are engineered to recognize only glucose. As a result, GBP-based glucose sensors are exceptionally accurate at low blood glucose levels and have a faster warm-up time than glucose oxidase based systems. The principal idea of this proposal is to evaluate the accuracy and performance of a second generation glucose binding protein-based continuous glucose monitor (GBP CGM) developed by BD Technologies in subjects with type 1 diabetes, with emphasis on warm-up period after insertion, accuracy in hypoglycemic and hyperglycemic ranges, and lag time over a 24 hour period of sensor use. In order to accomplish this, the investigators will conduct a clinical trial consisting of 25.5-hour studies involving 15 subjects, each wearing one active and one mock (no GBP) device simultaneously during meals and induced hypoglycemia to observe a wide range of glucose values. The investigators envision that the glucose binding protein-based continuous glucose monitor will demonstrate minimal warm-up time after insertion, overall accuracy comparable to commercial glucose oxidase sensors with excellent performance in the hypoglycemic range and a nominal lag time to sensing a change in blood glucose.

Inclusion criteria

• Clinical diagnosis of type 1 diabetes mellitus for ≥1 year. For an individual to be enrolled at least one criterion from each list must be met.
• Criteria for documented hyperglycemia (at least 1 must be met):

• Fasting glucose ≥126 mg/dL - confirmed
• Two-hour oral Glucose Tolerance Tests (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 (1 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 in adults (LADA) and did require insulin eventually and used continually
• Use of an insulin pump to treat his or her diabetes for at least six months prior to the study.
• Actively using a bolus calculator function with the current insulin pump with pre-defined parameters for glucose goal(s), carbohydrate ratio(s), and insulin sensitivity factor(s).
• Signed informed consent
• Age ≥21 and <65 years old
• Body mass index between 19 and 30 kg/m2, inclusive
• HbA1c ≤11%

Exclusion criteria

• Uncontrolled arterial hypertension (diastolic blood pressure >90 mm Hg and/or systolic blood pressure >160 mm Hg)
• Impaired hepatic function measured as alanine aminotransferase or aspartate aminotransferase ≥three times the upper reference limit
• Impaired renal function measured as creatinine >1.2 times above the upper limit of normal
• Diabetic ketoacidosis in the past 6 months
• Severe hypoglycemia resulting in a seizure or loss of consciousness in the 12 months prior to enrollment
• Conditions which may increase the risk of induced hypoglycemia such as known coronary artery disease, congestive heart failure, history of any cardiac disorder or arrhythmia, history of a cerebrovascular event, history of migraines, seizure disorder, syncope, adrenal insufficiency, or neurological disease.
• Current use of medications containing >4000 mg acetaminophen per day.
• Current use of L-Monoamine oxidases (MAO) inhibitors.
• 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
• Known allergy to eggs
• Pregnancy, breast-feeding or intention of becoming pregnant
• Current or recent alcohol or drug abuse by patient history.