Continuous Glucose Monitoring to Reduce Hypoglycemia and Improve Safety After Gastric Surgery
Condition: Hypoglycemia, Reactive; Hypoglycemia
MeSH terms: Hypoglycemia
Study type: Interventional

Summary: 
      The purpose of this study is to see if the use of a continuous glucose monitor (CGM) by
      people who experience low blood sugars (hypoglycemia) after gastric surgery can help reduce
      the number and severity of low blood sugar episodes.
    

Detailed description: 
      The CGM devices used in this study are approved by the Food and Drug Administration (FDA) for
      monitoring the glucose levels of people with diabetes. The investigators of this study are
      looking to see if these CGM devices are able to benefit people who have had gastric surgery
      and experience low blood sugar episodes, which can be asymptomatic and lead to complications,
      impairing safety. This study involves wearing a CGM sensor/transmitter during first a masked
      phase (unable to see CGM sensor glucose levels), followed by an unmasked phase (able to see
      and respond to sensor glucose levels and alarms). Participants are asked to regularly record
      fingerstick (capillary) blood sugar values and any symptoms experienced, as well as a record
      of treatments for symptoms and glucose levels.

      Participants attend three to five study visits: 5 visits for participants who wore the Dexcom
      G4, and 3 visits for participants who wore the Dexcom G6. The Dexcom G4 became unavailable
      during the course of the study when the G6 was introduced. (The Dexcom G4 had a 7 day wear
      period versus a 10 day wear period for the G6. As the G6 has a longer wear period, the
      frequency of the study visits was able to be decreased).

      This study also involves the use of a fitness tracker, which will be worn for the duration of
      the study and returned at the end of the study.

      Participants wearing the Dexcom G4 device were able to keep the Dexcom G4 CGM receiver and
      transmitter (this was not possible with the Dexcom G6 system).
    

Intervention name(s): Dexcom CGM masked; Dexcom CGM unmasked
Intervention type(s): Device; Device
Intervention description(s): The CGM will monitor sensor glucose levels in all participants. (Initially the Dexcom G4 was worn by participants (n=13); however, when the G4 became unavailable, the G6 was worn by the subsequent participants (n=10)).
The duration of the Dexcom G4 sensor was 7 days (2 sensors placed during each phase of participation) versus the Dexcom G6 whose sensor duration is 10 days (1 sensor placed during each phase of participation).; During the second phase (2 weeks for the Dexcom G4 and 10 days for the Dexcom G6), participants are able to see the sensor glucose levels displayed from the CGM. Participants will be instructed to use this information to treat low glucose levels before symptoms or severely low glucose levels develop.
The duration of the Dexcom G4 sensor was 7 days (2 sensors placed during each phase of participation) versus the Dexcom G6 whose sensor duration is 10 days (1 sensor placed during each phase of participation).
Allocation: Non-Randomized
Intervention model: Sequential Assignment
Intervention model description: The proposed study is designed to assess the efficacy of unmasked personal CGM to reduce the frequency of hypoglycemia after gastric surgery. Specifically, we will analyze glycemic patterns during a phase of baseline masked CGM wear (2 weeks for the Dexcom G4 or 10 days for the Dexcom G6), in comparison to a sequential, second phase of unmasked CGM wear (2 weeks for the Dexcom G4 or 10 days for the Dexcom G6). Please note that we have chosen to have a consistent masked monitoring first, as providing unmasked data to participants first could alter their dietary or other patterns and reduce ability of the study to independently assess efficacy of the CGM intervention.
Masking: None (Open Label)
Primary purpose: Treatment
Keywords: Post-bariatric Hypoglycemia;