This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record. Numerical trial results on this page are restricted to the results posted in the ClinicalTrials.gov record; calculations added by Clinical Biostats are labelled as such.
1. Trial at a Glance
This page covers the registry results for Integration of Continuous Glucose Monitoring Into a BiHormonal Closed-Loop Artificial Pancreas (NCT01161862), a randomized na study. The primary outcome is Mean Plasma Blood Glucose Achieved by the Bionic Pancreas (mg/dl).
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT01161862 |
| Phase | NA |
| Condition | Diabetes Mellitus |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | None (open label) |
| Enrollment | 24 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Boston University Charles River Campus |
| Results posted | Yes |
2. Clinical Question
Population
Participants with type 1 diabetes. The registry reports 24 participants overall, with 12 in each arm.
Intervention
A bi-hormonal artificial pancreas using insulin and glucagon, with meal-priming boluses. The first bolus was based solely on weight at 0.05 U/kg; later boluses were adapted online to target 75% of anticipated insulin needed during the first four hours after a meal began.
Comparator
A bi-hormonal artificial pancreas without meal-priming boluses. Its insulin controller was reactive to the estimated blood glucose signal from continuous glucose monitoring, with no meal announcements.
Primary question
What mean plasma blood glucose was achieved over 48 hours in each arm under the two approaches?
The central statistical contrast is between the groups’ mean plasma blood glucose during the stated observation period. The registry identifies a randomized, parallel-group comparison, but it does not report the arm-specific means, their variability, or a between-group estimate. It therefore does not establish from the record alone how the measured glucose values differed between the approaches, or how precise any difference might be.
The trial’s stated hypothesis concerned whether a closed-loop glucose-control system could use the estimated blood glucose signal from continuous glucose monitoring as the controller input. The arm descriptions distinguish whether meal-priming boluses were used; they do not describe a separate comparison of monitoring devices. Other outcomes listed in the registry concern glucose ranges, insulin use, hypoglycemia-related interventions and events, and glucose nadir. Their numerical results are not reported in the registry record.
3. Trial Design
The registry describes a randomized, parallel-group study with no masking. It lists an enrollment of 24 and reports 12 participants in each arm for the primary outcome. The study status is completed. The recorded start is 2010-07 and primary completion is 2012-12. The phase is listed as NA.
Both groups received a bi-hormonal artificial-pancreas approach using insulin and glucagon. The intervention contrast concerned meal-priming boluses. In the meal-priming arm, the first bolus was based solely on weight at 0.05 U/kg. Later meal-priming boluses were adapted online by the control system, targeting 75% of the anticipated insulin needed in the first four hours after a meal began. In the arm without meal-priming boluses, the insulin controller was described as entirely reactive to the continuous-monitoring glucose signal; there were no meal announcements.
Randomization indicates that assignment was intended to be made by chance, but the sequence-generation method, allocation concealment, and implementation details are not reported in the registry record. The record identifies no masking, so participants and study personnel were not described as blinded. It does not report how adherence, protocol deviations, or changes in treatment were handled.
The primary outcome is mean plasma blood glucose, with standard deviation as the stated measure of dispersion, over 48 hours. The registry also lists secondary outcomes involving time in glucose ranges, insulin total daily dose, carbohydrate interventions for hypoglycemia, blood glucose events below specified thresholds, and nadir blood glucose. The outcome values and the timeframes for those secondary measures are not reported in the registry record.
4. Participant Flow and Accounting
The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.
Overall Study
| Stage | Bi-hormonal Bionic Pancreas With Meal-priming Bolus | Bi-hormonal Bionic Pancreas With no Meal-priming Bolus |
|---|---|---|
| STARTED | 12 | 12 |
| COMPLETED | 12 | 12 |
| NOT COMPLETED | 0 | 0 |
Analysis population for the primary outcome, as defined in the registry: Overall number of participants was 24, 12 in each arm
5. Baseline Characteristics
The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.
| Characteristic | Unit | Bi-hormonal Pancreas With Meal-priming Bolus | Bi-hormonal Pancreas Without Meal-priming Bolus | Total |
|---|---|---|---|---|
| Participants analysed | 12 | 12 | 24 | |
| Age, Categorical: <=18 years | Participants | 6 | 6 | 12 |
| Age, Categorical: Between 18 and 65 years | Participants | 6 | 5 | 11 |
| Age, Categorical: >=65 years | Participants | 0 | 1 | 1 |
| Age, Continuous | years | 30 (SD 17.7) | 30.5 (SD 19.0) | 30 (SD 18) |
| Sex: Female, Male: Female | Participants | 7 | 8 | 15 |
| Sex: Female, Male: Male | Participants | 5 | 4 | 9 |
| Region of Enrollment: United States | participants | 12 | 12 | 24 |
6. Primary Endpoint
The registry lists the primary outcome as Mean Plasma Blood Glucose Achieved by the Bionic Pancreas (mg/dl), measured over 48 hours.
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | Standard Deviation |
| Unit | mg/dl |
| Endpoint classification | Continuous Endpoint |
The primary endpoint is mean plasma blood glucose achieved by the bionic pancreas, measured in mg/dl over 48 hours. A mean summarizes the central level of a continuous measurement across the observations included in its calculation. Comparing group means can describe whether average measured glucose differed between the randomized approaches during the stated period.
The registry names standard deviation as the measure of dispersion. In general, standard deviation describes how spread out individual measurements are around their mean; it is not itself a measure of how precisely the group mean has been estimated. Confidence intervals, if reported, would convey uncertainty around an estimated group difference. Neither arm-specific endpoint values nor a confidence interval for a comparison is reported in the registry record.
The precise aggregation used to produce the endpoint is not reported in the registry record. For example, the record does not specify whether measurements were first summarized for each participant and then across participants, or how missing or irregular glucose observations were handled. These details matter because repeated measurements from one participant are related, rather than independent observations. Without the outcome estimates and calculation details, the endpoint’s numerical result and its precision cannot be assessed from the registry entry.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry identifies mean plasma blood glucose over 48 hours as the primary outcome and names standard deviation as its dispersion measure. However, it does not report the mean for either arm, a difference between arms, or an uncertainty interval. As a result, the primary endpoint’s direction, magnitude, and precision are not reported in the registry record. No conclusion about the comparative glucose measurements can be drawn from the endpoint description alone.
The record lists secondary outcomes for time spent below glucose thresholds, time in the 70-180 mg/dl range, insulin total daily dose, carbohydrate interventions for hypoglycemia, events below a glucose threshold, and nadir glucose. It does not report numerical estimates for these outcomes. Their presence in the registry describes what was measured or intended for assessment; it does not establish what the measurements showed.
The registry marks the study completed and gives enrollment of 24, with 12 in each arm for the primary outcome. Those details describe the recorded study population, but they do not substitute for observed endpoint data. In particular, group size alone cannot show whether an estimated effect is large, small, or uncertain. A p-value, confidence interval, or other inferential result is not reported in the registry record.
The safety information reports no serious adverse events and no deaths in either arm, alongside one other adverse event in each arm. These are event counts in the registry record, not estimates of comparative safety. The record does not provide event descriptions, timing, attribution, or further detail about ascertainment. Small counts without that context cannot establish that risks were equivalent or that unlisted events did not occur.
Accordingly, interpretation must remain descriptive of what the registry records: the question, design, planned outcome measures, and limited adverse-event counts. It does not contain the primary or secondary outcome estimates needed to judge observed differences, nor the analysis details needed to understand how uncertainty and incomplete data were addressed.
9. Statistical Methods Explained
The registry describes a randomized, parallel-group design. In general, random assignment is intended to make treatment groups comparable on average with respect to both measured and unmeasured characteristics. It does not guarantee that every characteristic will be balanced in a particular study, especially when the enrollment is limited. The allocation method and any baseline comparisons are not reported in the registry record, so the balance achieved cannot be assessed from the entry.
What does the mean summarize?
The primary endpoint is a continuous measure: mean plasma blood glucose in mg/dl over 48 hours. A mean is useful for describing the central level of a continuous outcome and for framing a group comparison. The registry specifies standard deviation to describe spread around the mean. In general, standard deviation reflects variability among the measurements summarized; it does not directly quantify uncertainty in the estimated mean or in a difference between groups.
Repeated glucose readings from the same participant are usually correlated. General statistical practice accounts for the fact that readings from one person do not provide as much independent information as readings from different people. The registry record does not describe the sampling schedule, the aggregation of readings, or a model for repeated measures. It is therefore not possible to determine from the record how within-participant dependence was handled.
How would a group comparison be read?
A between-group estimate would describe the difference in mean glucose under the two assigned approaches. A confidence interval, in general, indicates a range of values reasonably compatible with the data and analysis assumptions; its width reflects precision. A p-value addresses compatibility with a specified null hypothesis under a statistical model, but does not show the size or practical importance of an effect. The registry record does not report a group difference, confidence interval, or p-value for the primary endpoint.
The registry’s stated planning assumptions describe an illustration based on an observed effect, with a two-sided significance level of 0.05, equal allocation, and a normal approximation. Such assumptions are not evidence that these methods formed the trial’s original design or final analysis plan. The registry does not report its sample-size justification or statistical analysis plan. Planning illustrations are not observed power, and cannot replace the actual effect estimate and uncertainty interval.
What do the secondary outcomes add?
The secondary outcomes cover glucose values below thresholds, time in the 70-180 mg/dl range, insulin total daily dose, carbohydrate interventions for hypoglycemia, blood glucose events below a threshold, and nadir blood glucose. These measures capture different aspects of glucose control and treatment use. In general, each endpoint requires a definition of the observation window, the analysis unit, and the handling of repeated measurements or events. The registry record does not report the numerical results or sufficient analytic detail to evaluate these choices.
For outcomes expressed as proportions of time, the denominator and handling of missing readings can affect interpretation. For counts of events, repeated events in one participant may require methods that account for clustering or over-dispersion, meaning variability greater than a simple model expects. These are general considerations, not claims about the analysis used in this study. The record does not report the relevant outcome definitions or models.
What can the planning assumptions establish?
A planning calculation asks what sample size might be needed under specified assumptions; it is not a finding about the participants enrolled. The registry describes an illustration using a stated fraction of the observed effect. It also distinguishes the planning unit for time-to-event outcomes from that for other outcomes. These assumptions do not reveal the trial’s original rationale, and the underlying endpoint estimates and resulting planning values are not reported in the registry record. No sample-size illustration should be read as observed power or as evidence that the study could reliably detect a particular difference.
Because the registry does not report the analysis plan, the handling of covariates, protocol deviations, repeated observations, missing data, or multiplicity is unknown. The available design description supports identification of the randomized comparison, but it does not allow independent reconstruction or appraisal of the statistical analysis.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists a primary outcome and secondary outcomes spanning glucose levels, insulin use, and hypoglycemia-related measures. Considering multiple outcomes can create multiplicity: when many hypotheses are tested, the chance of at least one apparently unusual result can increase. In general, investigators may address this through a prespecified hierarchy, adjustment, or a clearly exploratory interpretation. The registry record does not report a multiplicity strategy, so it is not possible to determine whether or how the analyses accounted for multiple comparisons.
The registry identifies the primary endpoint as mean plasma blood glucose over 48 hours and lists eight outcome measures. It does not provide numerical outcome results or report which outcomes were analyzed, beyond the listed measures. The outcome timeframes and detailed definitions for the secondary measures are not reported in the registry record.
Missing-data handling is also not reported in the registry record. The entry does not state whether all randomized participants contributed primary endpoint data, how incomplete glucose recordings were handled, or whether any imputation or sensitivity analysis was performed. The stated overall enrollment and allocation do not establish the number included in an analysis.
The analysis population is not reported in the registry record. It is therefore unclear whether analyses followed randomized assignment, included only participants meeting a protocol definition, or used another population. The record reports no analysis results, and the number of analyses is listed as zero. That does not establish that no analysis occurred; it means the registry entry does not provide analyses to evaluate. Without the analysis population, missing-data procedures, and multiplicity approach, the robustness of any outcome findings cannot be assessed.
11. Safety Results
The registry reports serious adverse events as affected participants divided by participants at risk.
| Arm | Participants with serious adverse events | Participants at risk | Percentage |
|---|---|---|---|
| Bi-hormonal With Meal Priming Bolus | 0 | 12 | 0.0% |
| Bi-hormonal Without Meal Priming Bolus | 0 | 12 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Bi-hormonal With Meal Priming Bolus | 0 of 12 |
| Bi-hormonal Without Meal Priming Bolus | 0 of 12 |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 0% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Bi-hormonal With Meal Priming Bolus | 1 of 12 |
| Bi-hormonal Without Meal Priming Bolus | 1 of 12 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Bi-hormonal With Meal Priming Bolus | Bi-hormonal Without Meal Priming Bolus |
|---|---|---|---|
| Nausea | General disorders | 1 of 12 | 1 of 12 |
The registry reports no serious adverse events in either arm and no deaths. It reports one other adverse event in the meal-priming arm and one in the arm without meal-priming boluses. These are recorded counts, not rates or comparisons adjusted for exposure or follow-up.
The serious-event counts should be read narrowly. A count of zero in the registry record means no serious adverse events were recorded for that group in this entry; it does not demonstrate that the approaches have identical safety profiles or that no event could occur. The record does not provide the names or descriptions of the other adverse events, their timing, seriousness criteria, relationship to the intervention, or how events were collected. It also does not report a statistical comparison of adverse events.
The registry’s safety counts are therefore descriptive. They offer limited information about events recorded during the study, but do not support a broad safety conclusion. Interpretation is constrained by the lack of event-level detail and the absence of reported comparative analyses.
12. What the Result Does, and Does Not, Mean
The record establishes that investigators conducted a completed randomized, parallel-group comparison of a bi-hormonal artificial-pancreas approach with meal-priming boluses against one without them. It identifies mean plasma blood glucose over 48 hours as the primary endpoint and reports 24 participants overall, with 12 in each arm. It also records the intended contrast between bolus strategies and lists additional glucose and treatment-use outcomes.
Those design details do not show what happened to the measured glucose values. The arm-specific means, their standard deviations, the difference between arms, and uncertainty around that difference are not reported in the registry record. The secondary outcome estimates are also not reported. The registry entry therefore cannot establish the direction or magnitude of any observed effect, or how precisely an effect was estimated.
The event counts provide a limited description of reported safety events: no serious adverse events or deaths are recorded in either arm, and one other adverse event is recorded in each. They do not establish equivalence or rule out uncommon or unrecorded events, particularly without descriptions, follow-up details, and an analysis of comparative risk.
More broadly, a registry description is not a substitute for outcome estimates and a transparent statistical analysis. The record does not report how missing observations, repeated glucose measurements, multiplicity, or analysis populations were handled. These gaps limit assessment of both the numerical findings and their reliability. The appropriate interpretation is that the registry specifies a clinical question and design but does not report the results needed to answer the comparative question.
13. Why This Trial Matters Statistically
This study is statistically informative as an example of a randomized comparison in which a continuous, repeatedly measured outcome is central. Mean plasma blood glucose over 48 hours can provide a concise summary, while standard deviation describes variation in the measurements. Interpreting such an endpoint requires knowing how readings were aggregated and how their within-participant correlation was handled. Those analytic details are not reported in the registry record.
The arm contrast is also specific: both approaches used a bi-hormonal artificial pancreas, while meal-priming bolus use differed. The description makes clear which strategy was compared, including the weight-based first bolus and subsequent online adaptation in one arm, and reactive control without meal announcements in the other. Accurate interpretation depends on maintaining that distinction rather than treating the study as a comparison of unrelated devices or monitoring systems.
The record also illustrates why design information and results answer different questions. Randomization and allocation describe how a comparison was organized; they do not reveal the observed effect or its precision. Enrollment figures alone cannot resolve that uncertainty. Without arm-level outcome values and an analysis, readers cannot judge the size, direction, or statistical uncertainty of the primary comparison.
Finally, the listed secondary outcomes show that a study may assess several complementary aspects of glucose control and treatment use. Their interpretation depends on outcome definitions, missing-data handling, and the approach to multiple comparisons. Since those details and estimates are absent, the record supports a careful account of the trial design, but not a complete statistical appraisal of its findings.
14. Limitations
- The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
- Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.
The main limitation for interpretation is that the registry record does not report the primary outcome values, standard deviations, or an estimate of the between-arm comparison. It therefore does not allow assessment of the magnitude, direction, or precision of the primary result. Numerical results for the listed secondary outcomes are also not reported.
Important analytic details are absent. The record does not describe how glucose readings were collected and aggregated, how within-participant repeated measurements were modeled, or how missing observations were handled. It does not report the analysis population, a statistical analysis plan, or any approach to multiplicity. The method used to generate the randomization sequence and conceal allocation is not reported in the registry record.
The primary endpoint has a stated timeframe of 48 hours, but the registry does not report the timeframes for the secondary outcomes. The adverse-event information is limited to counts; event descriptions, timing, attribution, and ascertainment details are not reported. No comparative safety analysis is reported.
The trial has 24 participants overall, with 12 in each arm. This recorded enrollment describes the study size but does not by itself establish precision or adequacy for any endpoint. The registry’s planning assumptions do not disclose the trial’s original sample-size justification, which is not reported in the registry record. Taken together, these gaps mean the entry is insufficient for reconstructing the analysis or evaluating the reliability of outcome findings.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Integration of Continuous Glucose Monitoring Into a BiHormonal Closed-Loop Artificial Pancreas — NCT01161862.
- Registry record last updated 2017-11-14; status last verified 2017-10.
- Results first posted 2017-11-14.
- Data retrieved from ClinicalTrials.gov on 2026-11-09.
- Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.
Continue through the Clinical Biostats statistical pathway
Use this trial's endpoint as a starting point for deeper study of effect measures, confidence intervals, and sample-size planning.
18. Record Summary
The registry describes a completed, randomized, parallel-group study with no masking of a bi-hormonal artificial-pancreas approach for automated management of type 1 diabetes. The comparison was between use of meal-priming boluses and a reactive insulin-control approach without meal announcements. Enrollment was 24, with 12 participants in each arm for the primary outcome.
The primary endpoint was mean plasma blood glucose in mg/dl over 48 hours, with standard deviation named as the dispersion measure. Secondary outcomes included glucose-range measures, insulin total daily dose, hypoglycemia-related interventions and events, and nadir glucose. The registry does not report numerical primary or secondary outcome estimates, the statistical analysis plan, missing-data procedures, or the analysis population.
Safety counts record no serious adverse events or deaths in either arm and one other adverse event in each. The limited event detail and absent outcome analyses constrain interpretation of the comparative findings.