Three-way, Cross-over Closed-loop Exercise Study
Condition: Type 1 Diabetes
MeSH terms: Diabetes Mellitus, Type 1
Study type: Interventional

Summary: 
      Blood glucose control systems that utilize both insulin and glucagon to manage blood sugar
      are paving the way to revolutionize the management of this disease. The benefit of improved
      control of blood sugar levels compared to standard insulin pump therapy has already been
      demonstrated. However, the risk of low blood sugar in type 1 diabetes increases considerably
      during exercise. The investigators research group has shown that small doses of glucagon can
      prevent low blood sugar when used in a blood sugar control system in patients with type 1
      diabetes. However, as insulin sensitivity changes occur very rapidly during exercise, the
      ability to recognize the onset of physical activity in order to appropriately adjust the
      insulin and glucagon delivery is vital to helping prevent exercise-induced hypoglycemia.

      The purpose of this study is to test how well a new modified blood sugar control system
      controls blood sugar during exercise compared to: 1) the current system without modifications
      and 2) standard insulin pump therapy.
    

Detailed description: 
      Subjects will exercise during three study visits. During one visit, blood sugar will be
      controlled using standard insulin pump therapy. The investigators blood glucose control
      system will manage blood sugar for subjects during the other visits, with exercise
      announcement with insulin and glucagon delivery modifications during one visit. Treatment
      order will be randomized. Heart rate and accelerometry data will also be collected during
      each visit for the purposes of designing an exercise detection system for future studies.

      Each subject will be asked to undergo an eligibility screening and to sign a consent form
      before any study procedures take place. At the screening appointment, after the consent form
      is signed, blood will be drawn for laboratory tests and a brief physical exam will be
      performed. An EKG and VO2max test will be completed at screening. Subjects that are enrolled
      in the study will come in for a sensor insertion visit up to 72 hours before each study
      visit. Subjects will undergo three 21-hour studies at an OHSU clinic or the OHSU clinical
      research center. Subjects will arrive at the research center at 8pm. Approximately 2 hours
      after a low-carbohydrate breakfast on Day 2, subjects will exercise for 45 minutes at 60% of
      their VO2max determined at screening. Three hours after completion of exercise, subjects will
      eat lunch. The study will end ~5 hours after lunch. Capillary blood glucose (CBG) will be
      measured every 2 hours during the day, every 3 hours at night and before and after exercise
      for studies using the blood glucose control system with subjects blinded to the CBG values.
      For studies using insulin pump therapy, the subject will sample CBG four times during the day
      as well as before and after exercise. Study staff will monitor studies remotely using a cloud
      server. An investigator or nurse practitioner with a specialty in endocrinology or internal
      medicine will be on site (located within the same complex) at all times.
    

Intervention name(s): Insulin pump therapy; Closed-loop Artificial Pancreas Controller
Intervention type(s): Device; Device
Intervention description(s): Subject's own insulin pump will be used to manage blood glucose.; Closed-loop Artificial Pancreas Controller includes insulin and glucagon delivery algorithm implemented on a smart phone, utilizing sensor glucose values from a Dexcom G4 sensor and sending delivery commands to two Tandem t:slim insulin pumps, one filled with insulin and one with glucagon.
Intervention MeSH terms: Pancrelipase
Allocation: Randomized
Intervention model: Crossover Assignment
Masking: None (Open Label)
Primary purpose: Treatment
Keywords: diabetes; closed-loop; bi-hormonal; exercise