Safety and Efficacy of Initializing the Control-IQ Artificial Pancreas System Using Total Daily Insulin: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Safety and Efficacy of Initializing the Control-IQ Artificial Pancreas System Using Total Daily Insulin (NCT03804983), a randomized na study. The primary outcome is Percent Time in Range at Home Pre/Post Intervention at Home.

2. Clinical Question

In practical terms, the study asked whether the home percent time in range differed between the pre-camp baseline period and the post-camp period for the two randomized device groups. The listed primary outcome title emphasizes a pre/post comparison at home, while the registry also identifies two randomized arms. The record does not give a single reported numerical comparison that resolves how the primary outcome was analyzed across those periods and arms. That analytical detail is not reported in the registry record.

The record lists secondary outcomes including average CGM at home and at camp, and percentages of CGM values below selected glucose thresholds at home or camp. These outcomes describe other aspects of CGM readings and time spent at lower values. Their names identify the planned measurements, but numerical findings for them are not reported in the registry record. The question can therefore be described from the outcome definitions and design, but the posted record does not establish the direction or size of a primary-outcome difference.

3. Trial Design

This was a randomized, parallel-group device study listed as completed. The registry identifies the sponsor as the University of Virginia and the condition as Type 1 Diabetes Mellitus. The study is marked as having no phase designation. Enrollment is listed as 22. The record lists two interventions: Hybrid Closed Loop (HCL) and Control-IQ with MyTDI. Participants were randomized 1:1 before a 72-hour ski admission, according to the arm descriptions.

The design includes home CGM data collection around the camp period. The primary outcome timeframe is 5 days post camp at home compared with 5 days before camp at baseline. The arm descriptions also refer to an approximately 5-day home data-collection period before the admission. They are truncated in the registry record, so further details about participant procedures and device use cannot be established from those descriptions. The record does not report whether the home observation periods were identical in every participant.

Masking is listed as none. In general, an unmasked trial is one in which masking is not used as part of the listed design; the record does not describe what participants, clinicians, or outcome assessors knew about allocation. The model is listed as parallel, meaning the study is organized around separate randomized groups rather than a crossover design. Further operational details of the randomization process, including sequence generation and allocation concealment, are not reported in the registry record.

The record lists 25 outcome measures and 19 analyses. It does not report a protocol-level account of how those measures were prioritized, how the analyses correspond to the listed outcomes, or which analysis population was used. Although the study is completed, completion status does not itself provide evidence about the size or precision of a treatment-group difference. Numerical results for the primary outcome 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.

Before assignment: 1 participant dropped prior to randomization for personal reasons (travel issues); 1 participant dropped prior to randomization as they didn't attend screening appointment.

Overall Study

Reasons for not completing this period:

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.

6. Primary Endpoint

The registry lists the primary outcome as Percent Time in Range at Home Pre/Post Intervention at Home, measured over 5 days post camp (home) compared to 5 days before camp (baseline).

The primary endpoint is the percentage of time spent in the glucose range from 70mg/dL to 180mg/dL while participants are at home. The registry defines it as the number of CGM values falling within that interval divided by the total number of available CGM values. The stated timeframe compares 5 days post camp at home with 5 days before camp at baseline.

In general, time in range condenses repeated glucose readings into a measure of how much observation time falls within a prespecified interval. It can be useful alongside an average because the same average can arise from different patterns of readings. The endpoint is expressed as a percentage of time, rather than as a glucose concentration. The record specifies that CGM gaps inferior to 3 hours will be linearly interpolated. In other words, under the stated rule, gaps shorter than 3 hours are filled by estimating values along a straight line between readings around the gap. The registry does not report further details about how longer gaps or other missing readings were handled.

The endpoint definition clarifies what is counted, but does not establish the observed result. The registry record does not report the group-specific endpoint values, the pre/post changes, or a statistical comparison. Consequently, the magnitude and precision of any difference cannot be assessed from the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry describes the primary outcome as a mean of a continuous measure and gives standard deviation as its dispersion. The outcome itself is a percentage of time in range derived from CGM values. The analysis approach used to compare groups or periods is not reported in the registry record. The explanations below describe general statistical concepts and should not be read as a claim that any particular method was used in this study.

What does the mean represent?

In general, a mean is an average across the observations included in a calculation. For this endpoint, the registry identifies percent time in range as the measure of interest. The mean can describe the average observed percentage across participants in a defined group or period, depending on the analysis. It does not show how much participants vary from one another, and it can conceal differences in the distribution of individual results. The registry record does not report the mean values or specify the analysis population from which a mean was calculated.

What does the standard deviation describe?

In general, the standard deviation describes how dispersed observations are around their mean. A larger standard deviation indicates greater spread in the observations, while a smaller one indicates closer clustering. It is not the same as a confidence interval: standard deviation describes variability among observations, whereas a confidence interval describes uncertainty about an estimated quantity under a statistical model. The registry lists standard deviation as the dispersion measure for the primary outcome, but does not report a numerical standard deviation for that outcome.

Why does the endpoint use CGM values?

The registry defines percent time in range as the number of available CGM values between 70mg/dL and 180mg/dL divided by the total number of available CGM values. In general, converting repeated sensor readings into a percentage gives a summary of the portion of observed time spent within the chosen interval. Interpretation depends on the recording period, availability of readings, and rules for handling gaps. The record specifies linear interpolation for CGM gaps inferior to 3 hours. It does not give further missing-data rules or detail the effect of interpolation on the reported endpoint.

What does randomization contribute?

In general, random allocation is intended to make comparison groups more similar, on average, with respect to measured and unmeasured characteristics at the start of a trial. It does not ensure that every feature is balanced in a small study, and it cannot replace clear reporting of the analysis and uncertainty. This record lists randomized allocation, 1:1, and a parallel model. It does not report the sequence-generation method, concealment procedures, stratification factors, or any adjustment variables. Those details should not be inferred from the word randomized.

Why is the analysis specification important?

For a pre/post outcome in a randomized study, the estimated contrast depends on what is compared and how repeated measurements are handled. For example, a between-group comparison of changes answers a different statistical question from a comparison of post-period values alone. These are general examples, not descriptions of the analysis performed in this trial. The registry record does not report the exact model, the contrast used for the primary outcome, how within-participant correlation was handled, or which covariates, if any, were included. It also does not report an inferential result for the primary endpoint.

A confidence interval would help describe the precision of an estimated contrast. In general, a narrow interval indicates greater precision than a wide interval, while the interval's compatibility with different effect sizes remains dependent on the analysis assumptions. A p-value, when reported, addresses how unusual the data would be under a specified null hypothesis and model; it is not a measure of effect size or clinical importance. Neither a confidence interval nor a p-value for the primary outcome is reported in the registry record. No inferential conclusion should be reconstructed from the endpoint definition alone.

How should planning calculations be understood?

The registry's sample-size assumptions describe a planning illustration based on the observed effect, using a two-sided significance level of 0.05, equal allocation between arms, and a normal approximation. The intended effect to detect is described as a stated fraction of the observed effect. The record does not report numeric planning-illustration results in the material summarized for this analysis. In general, such calculations ask what sample size would be needed under chosen assumptions; they do not describe the precision actually achieved in the trial.

Sample-size planning illustrations are not observed power. In general, observed power calculated from an observed effect adds little information beyond the estimate and its uncertainty. A planning calculation can also be highly dependent on the assumed effect and statistical model. The registry does not report a sample-size justification from the trial's own design, nor does it report whether the planning illustration corresponds to the original design process. No conclusion about whether enrollment met a prespecified target can be drawn from the planning assumptions alone.

What do the event counts say statistically?

Event counts are descriptive summaries. In general, a small number of observed events gives limited information about the range of event rates that could be compatible with the data. Counts also require definitions, observation periods, and complete reporting of event ascertainment to support a comparison. The registry lists serious, other, and fatal events separately, but does not report detailed definitions or event-level descriptions. The listed counts should therefore be read as a limited safety summary, not as a precise comparative estimate.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists 25 outcome measures and 19 analyses. When a study examines multiple outcomes or makes multiple statistical comparisons, the chance of obtaining at least one apparently notable result can increase. In general, multiplicity procedures may control that risk, or investigators may identify a primary comparison in advance and treat other analyses as secondary or exploratory. The registry record does not report a multiplicity adjustment, a hierarchy among all comparisons, or a prespecified statistical analysis plan. The existence and handling of any such plan are not reported in the registry record.

The primary endpoint definition includes a rule for CGM gaps inferior to 3 hours: those gaps will be linearly interpolated. This is a specific rule for short gaps, but the record does not describe how longer gaps, incomplete home periods, or other missing data were handled. It does not report the extent of missing CGM data, how missingness was assessed, or whether sensitivity analyses were performed. The record also does not state whether all randomized participants contributed data to the primary analysis.

Analysis populations are not specified in the registry record. It is therefore unclear from the record whether the analysis followed assignment regardless of device use, included only participants with available endpoint data, or used another population definition. This is an important distinction because exclusions or missing outcome data can affect the interpretation of a randomized comparison. The record does not report participant flow by analysis population or reasons for any missing observations.

These omissions limit the assessment of how robust any result would be to choices about multiplicity and missing data. They do not establish that an adjustment, sensitivity analysis, or particular analysis population was absent from study conduct; they mean those details are not reported in the registry record.

11. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Deaths

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 0% reporting threshold.

Most frequent non-serious adverse event terms

The registry's adverse-event summary lists 10 participants at risk in each group. It reports 0 serious adverse events in the Hybrid Closed Loop (HCL) group and 0 in the Control-IQ with MyTDI group. Deaths are listed as 0 in each group. For other adverse events, the record lists 0 in the HCL group and 1 in the Control-IQ with MyTDI group.

These figures are descriptive counts. In general, a count of zero means no event in that category was recorded in the listed group; it does not establish that an event is impossible or that risk is absent. A count alone also does not quantify uncertainty or explain how events were defined and collected. The registry record does not describe the other adverse event, its timing, its severity, its relationship to the device, or whether it led to a change in participation.

The safety figures should be interpreted within the reported study context and not as a stand-alone comparison of event rates. The record does not provide further event-level detail or a statistical comparison of safety outcomes. In particular, the serious-event and death counts do not provide evidence about unreported events or longer-term safety beyond what the registry record describes.

12. What the Result Does, and Does Not, Mean

The record establishes that a randomized, parallel-group device study was completed and identifies percent time in range at home as its primary outcome. It specifies the glucose interval used to define time in range, the pre- and post-camp home observation periods, and a rule for interpolating short CGM gaps. It also lists secondary CGM outcomes and a limited summary of adverse-event counts. These are useful elements for understanding what the study set out to examine.

The registry record does not report the numerical primary-outcome result. It therefore does not show the observed percent time in range in either group, the change from baseline, the between-group contrast, or the precision of any estimate. Without those results, the record cannot establish the direction or size of a difference in the primary endpoint. It also cannot show whether any difference was statistically compatible with a range of effects that would matter to researchers or participants.

Likewise, the listed adverse-event counts should not be expanded into a broader claim about safety. The record reports no serious adverse events or deaths in either group, and one other adverse event in the MyTDI group, but gives no event details. The counts do not resolve the probability of uncommon events or risks beyond the observation described in the record.

In general, a trial result is best interpreted by considering the estimated effect, its uncertainty, the analysis population, missing-data handling, and the prespecified analysis plan. Several of these details and the numerical endpoint findings are not reported in the registry record. The record can describe the research question and selected methods, but it does not support a conclusion about the comparative performance of the two device approaches.

13. Why This Trial Matters Statistically

This study is statistically interesting because it combines a randomized device comparison with CGM measurements collected across home periods surrounding a 72-hour ski admission. The primary endpoint is based on repeated sensor readings, but is summarized as percent time in a prespecified range. That structure makes both the definition of available observation time and the handling of data gaps relevant to interpretation. The record explicitly identifies linear interpolation for CGM gaps inferior to 3 hours.

The pre/post framing also makes the comparison estimand important. In general, a change over time within a group and a difference in changes between randomized groups are distinct quantities. The registry gives the primary outcome title and timeframe but does not report the exact analytical contrast. This illustrates why endpoint names and study design labels alone are not enough to reconstruct a statistical result.

The record lists 25 outcome measures and 19 analyses, while it does not report a multiplicity strategy or a full analysis plan. In general, clear prioritization and transparent reporting help readers distinguish confirmatory questions from additional exploratory measurements. The safety summary is similarly limited: it reports event counts but not event descriptions or comparative uncertainty.

Most importantly, the record identifies a clear primary measurement but does not report its numerical result. That gap separates the question a trial set out to answer from the evidence a reader can evaluate in the registry record. Statistical interpretation requires not only a defined endpoint and randomized design, but also reported estimates and enough methodological detail to assess their precision and robustness.

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 interpreting this trial from the registry record is the absence of numerical results for the primary outcome. Group-specific percent time in range, pre/post changes, a between-group estimate, and uncertainty measures are not reported. The record therefore does not permit an assessment of the direction, magnitude, or precision of the primary comparison.

The primary outcome title refers to a pre/post comparison at home, but the exact statistical contrast and model are not reported. The record does not state how repeated measurements were handled, whether an adjustment was made, or which analysis population was used. It also does not report a participant-flow account tied to endpoint availability or reasons for missing data. Linear interpolation is specified for CGM gaps inferior to 3 hours, but handling of other gaps is not reported.

The study is listed as unmasked. The registry does not describe the masking status of any outcome assessors or the process used to conceal allocation. Randomization sequence generation and allocation concealment are also not reported. The arm descriptions are truncated, limiting what can be learned about procedures and device use from the record.

The registry lists 25 outcome measures and 19 analyses but does not report a multiplicity strategy or a detailed analysis plan. Numerical results for the listed secondary outcomes are not reported in the registry record. The adverse-event summary does not include event descriptions, timing, relatedness, or additional clinical detail. These reporting limitations do not prove that the information was not collected; they constrain what can be concluded from the registry record.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Safety and Efficacy of Initializing the Control-IQ Artificial Pancreas System Using Total Daily Insulin — NCT03804983.
• Registry record last updated 2024-08-01; status last verified 2024-07.
• Results first posted 2024-08-01.
• 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.

18. Record Summary

The registry record describes a completed, randomized, parallel-group device study sponsored by the University of Virginia, concerning Type 1 Diabetes Mellitus. Enrollment is listed as 22. Participants were randomized 1:1 to Hybrid Closed Loop (HCL) or Control-IQ with MyTDI before a 72-hour ski admission. The study is listed as unmasked, with no phase designation.

The primary outcome is percent time in range at home, comparing 5 days post camp with 5 days before camp at baseline. It is defined using CGM values between 70mg/dL and 180mg/dL, with linear interpolation for gaps inferior to 3 hours. The registry lists 25 outcome measures and 19 analyses, but does not report numerical primary-outcome findings or a detailed statistical analysis plan.

The safety summary lists 0 serious adverse events and 0 deaths in each group, and lists 0 other adverse events in HCL and 1 in Control-IQ with MyTDI. Further event details are not reported in the registry record.