Accelerometer Use in the Prevention of Exercise-Associated Hypoglycemia in Type 1 Diabetes: Outpatient Exercise Protocol

December 17, 2019 updated by: Bruce Buckingham, Stanford University

Manually suspending an insulin pump at the beginning of aerobic exercise reduces the risk of exercise-associated hypoglycemia (low blood sugar) in patients with type 1 diabetes (T1D). However, since patients with T1D often do not make exercise-related adjustments to their insulin regimen, our group has developed an algorithm to initiate pump suspension in a user-independent manner upon projecting exercise-associated hypoglycemia. The current study seeks to test the efficacy of this algorithm by asking users to participate in a sports camp while wearing an insulin pump, continuous glucose monitor, and accelerometer/heart rate monitor (to detect exercise), which will communicate electronically to a pump shutoff algorithm. On one of the days the algorithm will be used, while on the other day their normal insulin rate will continue for comparative purposes.

The investigators hypothesize that the use of an accelerometer-augmented computer algorithm for insulin pump suspension during exercise will result in significantly fewer episodes of hypoglycemia (both during exercise and in post-exercise monitoring) than in exercise without a pump suspension algorithm.

Study Overview

Status

Completed

Conditions

Intervention / Treatment

Detailed Description

Regular aerobic exercise confers a plethora of health benefits to all individuals and is considered an essential component of the management of type 1 diabetes (T1D) [1]. However, in contrast to non-diabetic subjects - in whom the increased muscle energy requirement during exercise leads to suppression of endogenous insulin secretion - patients with T1D are dependent upon exogenous insulin and are thus at risk for exercise-associated hypoglycemia [1]. Exercise-associated hypoglycemia is the most frequently reported adverse event related to exercise in diabetes [2] and hypoglycemia can occur during exercise or several hours afterwards [3,4]. Although previous research has shown that pre-meal dose reduction of subcutaneous insulin can be effective at decreasing the incidence of exercise-associated hypoglycemia [5], patients with T1D often do not perform such adjustments [6,7].

In contrast to subcutaneous insulin injections, which are reliant upon the patient or caretaker to determine dosage, the insulin pump provides a unique opportunity to avoid hypoglycemia via user-independent, computer-based algorithms for determining insulin delivery. Previous research conducted here at Stanford has demonstrated that algorithms based on continuous glucose monitor (CGM) data can prevent hypoglycemia in the sedentary setting by inducing insulin pump suspension [8-10]. In addition, a study of children and adolescents conducted at Stanford (as a center in the DirecNet group) demonstrated that suspending an insulin pump at the beginning of a period of moderate aerobic exercise reduces the risk of hypoglycemia during that exercise period and subsequently overnight [11]. Thus, by utilizing exercise-detecting accelerometers and an algorithm to initiate pump suspension during exercise, it is likely possible that people with diabetes could avoid exercise-associated hypoglycemia even if they failed to manually alter their pump settings. However, to date, no published studies have utilized accelerometer-derived data in an insulin pump suspension algorithm during exercise.

Accelerometers are light-weight motion-sensing devices that can be worn to provide information about the intensity and duration of physical activity [12]. They are small, inexpensive, and could easily be incorporated into current sensors and "patch" pumps. They can also be used independently or combined with a heart rate monitor (HRM) [13], although most commercially available HRMs currently require a chest strap that can be uncomfortable to wear. Previous studies evaluating the effect of physical activity on insulin sensitivity have utilized accelerometers (worn on a belt at the small of the back, the right side of the trunk in the mid-axillary line, or the left side of the chest) with and without HRMs for activity recognition during subjects' everyday lives. These data were used to classify activity as sedentary, light, moderate, or vigorous based on acceleration signal counts measured over one-minute intervals [13-17]. One study investigated four different accelerometers in a clinical research setting and found each to be very accurate in assessing the intensity of physical activity, regardless of subjects' body habitus [18]. Thus, these devices can provide a reliable means by which the onset, duration, and intensity of exercise can be recognized and reported in real-time to the other components of an artificial pancreas. When combined with CGM and insulin delivery data, this exercise information is a valuable tool in designing an algorithm to decrease or stop insulin delivery in order to decrease the risk of exercise-associated hypoglycemia.

In the first phase of this study (in press), 22 subjects with type 1 diabetes went about their everyday lives while wearing an insulin pump, CGM, and accelerometer/heart rate monitor. After the monitoring period, the devices were downloaded and the data were used to augment an existing predictive low glucose suspend (PLGS) algorithm to incorporate activity. In a computer simulator, the PLGS algorithm reduced hypoglycemia by 64%, compared to 73% and 76% reductions for the accelerometer-augmented and HRM-augmented algorithms, respectively.

In the next phase of this study, we seek to test the newly developed algorithm in a real-life setting in the form of a structured sports (soccer) camp to further see if modifications to the algorithm are required.

Study Type

Interventional

Enrollment (Actual)

18

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • United States
    • California
      • Stanford, California, United States, 94305
        • Stanford University

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

8 years to 25 years (Child, Adult)

Accepts Healthy Volunteers

No

Genders Eligible for Study

All

Description

Inclusion Criteria:

  • Clinical diagnosis of type 1 diabetes for 1-20 years. The diagnosis of type 1 diabetes is based on the investigator's judgment; C peptide level and antibody determinations are not needed.
  • Age 8 to 25 years old.
  • On daily use of an insulin pump and not anticipating a change prior to the subject's completion of the study.
  • Willingness to allow for CGM insertion (if not already using a study-designated CGM) for use during the study.
  • HbA1c <10%.
  • Parent/guardian and subject understand the study protocol and agree to comply with it.
  • Informed Consent Form signed by the parent/guardian and Child Assent Form signed.

Exclusion Criteria:

  • A history of recent injury to body or limb, Addison's disease, muscular disorder, organ/bone marrow transplant, heart disease, or use of any medication or other significant medical disorder if that injury, medication or disease in the judgment of the investigator will affect the completion of the exercise protocol.
  • Current use of glucocorticoid medication (by any route of administration).
  • Current use of a beta blocker medication.
  • Severe hypoglycemia resulting in seizure or loss of consciousness in the four weeks prior to sports camp (if a severe episode occurs after the first but prior to the scheduled second admission, the visit will be deferred).
  • Active infection (if at the time of the planned second visit an infection is present, the visit will be deferred).

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Crossover Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: On-algorithm first, then Off-algorithm
Users will participate in two sports camp sessions while wearing an insulin pump, continuous glucose monitor, and accelerometer/heart rate monitor (to detect exercise), which can communicate electronically to a pump shutoff algorithm that insulin delivery should be shut off. On one sports day, the algorithm is turned on; on the other day, the algorithm is turned off.
Device: Computer algorithm to initiate pump suspension
If the computer algorithm senses impending risk for hypoglycemia it sends an alert to an on-site physician to recommend a manual suspension of the subject's insulin pump
Other Names:
  • Augmented predictive low glucose suspend algorithm
Experimental: Off-algorithm first, then On-algorithm
Users will participate in two sports camp sessions while wearing an insulin pump, continuous glucose monitor, and accelerometer/heart rate monitor (to detect exercise), which can communicate electronically to a pump shutoff algorithm that insulin delivery should be shut off. On one sports day, the algorithm is turned on; on the other day, the algorithm is turned off.
Device: Computer algorithm to initiate pump suspension
If the computer algorithm senses impending risk for hypoglycemia it sends an alert to an on-site physician to recommend a manual suspension of the subject's insulin pump
Other Names:
  • Augmented predictive low glucose suspend algorithm

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Count of Participants Experiencing a Hypoglycemic Event During Scheduled Exercise
Time Frame: Measurements occurring during exercise (up to 8 hours)
The primary outcome will be a hypoglycemic event defined as (1) any meter blood glucose (BG) reading of ≤60 mg/dl, (2) two consecutive meter BG readings ≤70 mg/dl done within one hour, or (3) any instance in which carbohydrates were given at a subject's request for symptoms of hypoglycemia
Measurements occurring during exercise (up to 8 hours)

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Count of Participants With Hypoglycemia in the Post Exercise Period
Time Frame: In the time following exercise until the following morning (up to 24 hours)
A hypoglycemic event was defined as (1) any meter blood glucose (BG) reading of ≤60 mg/dl, (2) two consecutive meter BG readings ≤70 mg/dl done within one hour, or (3) any instance in which carbohydrates were given at a subject's request for symptoms of hypoglycemia
In the time following exercise until the following morning (up to 24 hours)

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Stanford University

Investigators

  • Principal Investigator: Bruce A Buckingham, MD, Stanford University

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

March 12, 2014

Primary Completion (Actual)

May 1, 2014

Study Completion (Actual)

May 1, 2014

Study Registration Dates

First Submitted

January 17, 2014

First Submitted That Met QC Criteria

January 24, 2014

First Posted (Estimate)

January 28, 2014

Study Record Updates

Last Update Posted (Actual)

December 27, 2019

Last Update Submitted That Met QC Criteria

December 17, 2019

Last Verified

December 1, 2019

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • 29205

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

Yes

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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