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 CGM Use in Poorly Controlled Youth With Type 1 Diabetes (NCT04721145), a na na study. The primary outcome is Change in Personal CGM Use.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT04721145 |
| Phase | NA |
| Condition | Type 1 Diabetes, Hypoglycemia, High Blood Sugar |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 26 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Johns Hopkins University |
| Results posted | Yes |
2. Clinical Question
Population
The study concerns children with type 1 diabetes described as high-risk and poorly controlled. The registry record also lists hypoglycemia and high blood sugar as conditions. Enrollment is recorded as 26. Further eligibility details, including how high risk or poor control was defined, are not reported in the registry record.
Intervention
Participants were to trial a Dexcom G6 continuous glucose monitor for a 10-day wear period. The stated purpose was to assess whether trial use was followed by increased uptake of personal CGM use and improved short-term time-in-range glucose control. The registry describes the device as the intervention.
Comparator
The design is listed as single group, with allocation recorded as NA and masking as NONE. No concurrent control group or randomized comparison is identified in the registry record. The central comparison is therefore within the study group over time, rather than a treatment-versus-control contrast.
Primary question
The primary outcome is change in personal CGM use, assessed at baseline and 3 months. The registry description asks whether uptake changes after the 10-day trial. The outcome is expressed as participants, but the exact rule used to classify personal CGM use or define a change is not reported in the registry record.
Statistically, this is a before-and-after question about adoption of personal monitoring in a high-risk pediatric group. It is distinct from the secondary questions about time in range, hemoglobin A1c, and personal CGM use. The registry record does not report a primary outcome estimate, so the direction and precision of any change cannot be assessed from the recorded information.
3. Trial Design
The registry describes IMPaCT as a prospective, single-group study of a Dexcom G6 continuous glucose monitor in high-risk, poorly controlled children with type 1 diabetes. The intervention is a 10-day period of CGM wear. The study status is COMPLETED, and enrollment is recorded as 26. The phase is listed as NA. The start date is 2021-01-25, and the primary completion date is 2022-06-28.
Allocation is recorded as NA, masking as NONE, and the model as SINGLE GROUP. These entries describe a study without a randomized, masked, concurrent comparison arm in the registry record. The primary question is framed as change in personal CGM use from baseline to 3 months, following the trial period. A before-and-after design can describe change over time in the study group, but it does not by itself separate the effect of the device trial from other changes that may occur during the same period. That is a general limitation of interpreting uncontrolled changes, not evidence that any particular outside influence occurred in this study.
The registry lists four outcome measures and three named secondary outcomes: change in percent time in range glucose control, change in hemoglobin A1c, and using personal CGM. It also records zero analyses. The record does not report the detailed schedule for each secondary outcome, the procedures for participant follow-up, or the statistical analysis plan. Those omissions mean that the completed status should not be read as a complete account of the results or of how the analyses were conducted.
The brief description identifies uptake of personal CGM and short-term time-in-range control as goals. However, the primary outcome result and numerical results for the secondary outcomes are not reported in the registry record. The design can therefore be described, but the clinical and statistical findings cannot be reconstructed from these entries.
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 | Dexcom G6 Continuous Glucose Monitor |
|---|---|
| STARTED | 26 |
| COMPLETED | 26 |
| NOT COMPLETED | 0 |
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 | Dexcom G6 Continuous Glucose Monitor |
|---|---|---|
| Participants analysed | 26 | |
| Age, Continuous | years | 14.1 (SD 2.9) |
| Sex: Female, Male: Female | Participants | 9 |
| Sex: Female, Male: Male | Participants | 17 |
| Race/Ethnicity, Customized: Race/Ethnicity – Non-Hispanic White | Participants | 11 |
| Race/Ethnicity, Customized: Race/Ethnicity – Non-Hispanic Black | Participants | 11 |
| Race/Ethnicity, Customized: Race/Ethnicity – Hispanic | Participants | 3 |
| Race/Ethnicity, Customized: Race/Ethnicity – Multi-racial (American Indian / White) | Participants | 1 |
| Region of Enrollment: United States | Participants | 26 |
| Insurance: Public Insurance | Participants | 17 |
| Insurance: Private Insurance | Participants | 9 |
| HbA1c | Percentage | 10.7 (SD 2.4) |
6. Primary Endpoint
The registry lists the primary outcome as Change in Personal CGM Use, measured over Baseline and 3 months.
| Element | Registry entry |
|---|---|
| Result type | Count Of Participants |
| Measure of spread | not applicable |
| Unit | Participants |
| Endpoint classification | Binary Endpoint |
The primary endpoint is titled Change in Personal CGM Use. It is recorded in participants, with assessment at baseline and 3 months. The accompanying description asks whether uptake of personal CGM changes after the 10-day trial. In plain terms, the outcome concerns adoption of personal CGM rather than glucose values alone.
A participant-count outcome is useful for expressing uptake in a way that relates directly to implementation: it can represent how many participants meet a defined criterion for personal CGM use. The registry’s outcome type is described as participants with an event, using counts. However, the event definition is not reported in the registry record. It is therefore unclear from these entries what exact use threshold or classification rule distinguishes uptake from non-uptake, or how a change between baseline and follow-up is represented.
Assessing the endpoint at baseline and 3 months makes it possible in principle to describe change over time. For a repeated measure on the same participants, a sound analysis generally needs to respect the pairing between baseline and follow-up values; this is a general statistical consideration. The registry record does not state the analysis method, the number with data at each assessment, or a numerical change estimate.
The endpoint is relevant to the stated aim of evaluating whether a brief trial period is followed by personal CGM use. It does not, by itself, measure glucose control, which is addressed by separately named secondary outcomes. Without the observed outcome and a clear event definition, neither the magnitude nor the precision of the primary change can be interpreted.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record identifies a clinically focused question but does not report a numerical result for the primary outcome. It therefore does not establish whether personal CGM use increased, decreased, or remained unchanged between baseline and 3 months. No effect estimate, confidence interval, or test result for this endpoint is reported in the registry record. Without those quantities, the magnitude and precision of any change cannot be evaluated.
The design is single group, with no concurrent comparison identified. A baseline-to-follow-up change can show what happened over time among participants with recorded observations, but an uncontrolled change cannot isolate the effect of the 10-day device trial. General influences over time, differences in participant circumstances, or other care changes could also contribute to a before-and-after pattern. The registry record does not say whether any such influences occurred, so they should be treated as possible explanations rather than findings.
The record names secondary outcomes concerning time in range, hemoglobin A1c, and personal CGM use. Their numerical results are not reported in the registry record. The brief summary states the study’s goals, but a goal is not an observed result. Accordingly, no conclusion about the direction or size of changes in glucose control can be drawn from the recorded outcome information.
Safety information is recorded for the Dexcom G6 group: 5 participants are listed with a serious event, 1 with an other event, and deaths are recorded as 0. The registry also lists DKA admission at 15.4%, ER Visit, renal stone at 3.8%, and Abdominal Pain at 3.8% among the top serious terms. These are safety entries, not evidence about the primary uptake endpoint. The record does not provide enough information to attribute an event to the device or to compare event rates against a control group.
Overall, the available entries describe the study design, its intended questions, and selected safety counts, but not its efficacy results or statistical uncertainty. The completed status does not fill that gap. A result should be interpreted only when its definition, estimate, and uncertainty are available; these are not reported for the primary outcome in the registry record.
9. Statistical Methods Explained
The registry record identifies the primary outcome as a count of participants and lists baseline and 3 months as the assessment times. The study model is single group. These features determine what kinds of statistical interpretation are relevant, but the record does not provide a statistical analysis plan or an outcome analysis. The explanations below describe general principles, not methods confirmed as having been used in this study.
What does a participant count represent?
A count records how many participants meet a specified condition. For an uptake outcome, that condition might be a registry-defined classification of personal CGM use, but the exact definition is not reported in the registry record. A count alone is not always enough to interpret an outcome: the relevant population, event definition, assessment time, and amount of missing information also matter. The record names the unit as participants and the outcome as change in personal CGM use, but it does not state the detailed classification rule or provide the observed count.
If the outcome is represented as an event or no event for each participant, an analysis may describe the event count and the proportion of participants meeting the event definition. Those are distinct summaries: a count depends on how many participants were assessed, while a proportion also requires a clearly defined denominator. No primary outcome count or denominator at follow-up is reported in the registry record, so neither summary can be evaluated from these entries.
Why does the before-and-after structure matter?
When a measurement is taken at baseline and again later for the same participants, the two observations are related. General statistical methods for repeated measurements account for that relationship rather than treating each measurement as if it came from unrelated people. For a binary uptake outcome, the pattern of individual transitions between use and non-use can be important; the group-level counts at each time alone may not reveal those transitions. The registry record does not report transition data or the method used to analyze the repeated outcome.
A change over time in a single group is also different from a randomized comparison. In a randomized trial, a comparison group can help separate changes associated with the intervention from changes that would have occurred without it, subject to the trial’s design and implementation. No such comparison is identified. Consequently, even a numerical before-and-after difference would describe change during the study period, not by itself establish that the device trial caused that change.
How should uncertainty be understood?
In general, a confidence interval expresses uncertainty around an estimate. A narrow interval indicates greater precision under the assumptions of the analysis; a wide interval indicates less precision. For a count or proportion, uncertainty depends on the amount of information and on the statistical model. An interval is not a guarantee that the true value lies within its limits, and it does not correct a biased design or an incomplete outcome definition. No confidence interval for the primary endpoint is reported in the registry record.
A p-value, when used, addresses how compatible the observed data are with a specified null model, under the assumptions of the test. It does not quantify the size or importance of an effect and does not establish causation. The registry record lists zero analyses and does not report a primary-outcome p-value or a testing plan. It is therefore not possible to determine whether a formal hypothesis test was performed or how any result was interpreted.
What do the planning assumptions mean?
The registry’s planning statement describes illustrations computed from an observed effect, not the trial’s own design. It specifies a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation, with the effect to detect set as a stated fraction of the observed effect. It also distinguishes total events for time-to-event calculations from participants per arm for other calculations. These are assumptions for hypothetical planning exercises; they do not describe this study’s single-group allocation and should not be mistaken for an observed analysis or the original sample-size justification. The registry record does not report the protocol’s sample-size justification.
In general, a planning estimate asks how much information a future study might require to detect a chosen effect under stated assumptions. It is not observed power and cannot establish that the completed study had adequate power. Estimates based on a study’s observed effect can also be unstable, particularly when the observed effect is imprecise. The numerical planning estimates and the observed primary effect are not reported in the registry record, so the assumptions cannot be checked against a result in these entries.
Why do distributional assumptions matter?
Statistical models make assumptions about how outcomes vary. For event counts, over-dispersion means that the observed variability is greater than a model’s assumptions would allow. If ignored, uncertainty can be understated and inference can appear more precise than warranted. This is a general consideration for count data, not a finding about this study. The primary outcome is described as participants with an event, but the record does not report an analysis model or enough outcome data to assess whether over-dispersion is relevant.
For all these reasons, the design and outcome label alone do not identify the analysis that was actually used. The analysis method, estimate, uncertainty, handling of missing observations, and any adjustment strategy are not reported in the registry record. Interpretation should remain descriptive until those details and the primary outcome results are available.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists four outcome measures, including the primary outcome and named secondary outcomes concerning time in range, hemoglobin A1c, and personal CGM use. Testing or estimating several outcomes creates a multiplicity issue: the more questions examined, the greater the chance that at least one apparently notable finding may arise by chance when formal tests are used. General approaches include identifying a primary outcome in advance, prespecifying a hierarchy, or adjusting inference across a family of tests. The registry record does not report a multiplicity strategy, an analysis hierarchy, or a statistical analysis plan.
The record lists zero analyses. It does not report outcome estimates, p-values, confidence intervals, or which outcomes were included in any completed analysis. As a result, it is not possible to determine how multiplicity was handled or whether formal statistical testing was conducted.
Missing data also affect interpretation. In a baseline-to-follow-up study, participants may have information at both assessments, at only one assessment, or at neither. The number with observed data at each time, reasons for missingness, and methods for handling missing observations are not reported in the registry record. General methods differ in their assumptions about why data are missing; those assumptions can affect estimates and uncertainty.
The analysis population is not reported in the registry record. It is not stated whether analyses included all enrolled participants, only those completing follow-up, or another defined group. No analysis should be assumed to use a particular population or missing-data method on the basis of the study status alone.
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 |
|---|---|---|---|
| Dexcom G6 Continuous Glucose Monitor | 5 | 26 | 19.2% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Dexcom G6 Continuous Glucose Monitor | 0 of 26 |
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 |
|---|---|
| Dexcom G6 Continuous Glucose Monitor | 1 of 26 |
Most frequent serious adverse event terms
| Event term | Organ system | Dexcom G6 Continuous Glucose Monitor |
|---|---|---|
| DKA admission | Endocrine disorders | 4 of 26 |
| ER Visit, renal stone | Renal and urinary disorders | 1 of 26 |
| Abdominal Pain | Gastrointestinal disorders | 1 of 26 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Dexcom G6 Continuous Glucose Monitor |
|---|---|---|
| Otalgia of both ears | Ear and labyrinth disorders | 1 of 26 |
Serious events with the highest arm-level rate: dka admission (15.4%), er visit, renal stone (3.8%), abdominal pain (3.8%).
For the Dexcom G6 group, the registry record lists 26 participants at risk for serious events and 5 affected by a serious event. It lists 26 at risk for other events and 1 affected by an other event. Deaths are recorded as 0. These entries describe the safety counts recorded for this group; they do not establish that an event was caused by the device.
The top serious terms listed are DKA admission at 15.4%, ER Visit, renal stone at 3.8%, and Abdominal Pain at 3.8%. These terms and percentages are registry safety entries. They should not be interpreted as comparative risks, since no control group is identified. The record does not report event-level timing, adjudication, relatedness to the intervention, or a comparison suitable for estimating excess risk.
Counts of participants affected are not necessarily counts of total event occurrences, and a participant may have more than one recorded event. The registry entries do not clarify the relationship between the listed terms and the group-level affected counts. The safety information should therefore be read as descriptive reporting, not as a causal safety analysis or a basis for comparing treatments.
12. What the Result Does, and Does Not, Mean
The study addresses whether a short trial of a Dexcom G6 continuous glucose monitor is followed by a change in personal CGM use among high-risk, poorly controlled children with type 1 diabetes. That is an implementation-focused question, distinct from asking whether glucose-control measures change. The registry record identifies both uptake and short-term time-in-range control as goals, and lists hemoglobin A1c and personal CGM use among the secondary outcomes.
The completed status and enrollment entry describe the registry record, but they do not supply the outcome findings. The primary result is not reported in the registry record. It is therefore not possible to state whether personal CGM uptake changed, how large any change was, or how precisely it was estimated. Results for the named secondary outcomes are also not reported in the registry record.
Even if a before-and-after change were available, a single-group design would support a description of change over time, not a definitive attribution of that change to the device trial. There is no concurrent control comparison identified in the registry record. This is a general limitation of uncontrolled designs; it does not imply that the intervention had no effect, nor does it establish that it had an effect.
The safety entries report affected-participant counts and selected serious-event terms, but do not establish causality or comparative safety. The registry record does not provide the contextual details needed to interpret event timing, relatedness, or a difference from another group.
Thus, the record establishes what question the study set out to address and how the study was structured. It does not establish the direction, magnitude, or uncertainty of the primary outcome, nor does it support a causal conclusion about uptake or glucose control. No clinical recommendation follows from these registry entries alone.
13. Why This Trial Matters Statistically
This study illustrates a common distinction in clinical research: measuring whether an intervention is followed by adoption is not the same as measuring its effect against a control group. Personal CGM uptake is an implementation outcome, while time in range and hemoglobin A1c concern glucose control. Keeping these questions distinct helps readers avoid treating a change in device use as equivalent to a change in clinical measures.
The study is also a useful example of why a clear outcome definition matters. A participant count is interpretable only when the event or use criterion, assessment time, and analysis population are clear. The registry names change in personal CGM use and gives baseline and 3 months as time points, but does not report the specific use classification rule or the numerical result. Without those details, even a seemingly simple adoption question cannot be independently interpreted.
Its single-group structure makes causal interpretation especially important. A before-and-after comparison can be informative about what happened in the study group, but changes during follow-up may have explanations other than the intervention. The absence of a concurrent comparison does not make descriptive observations useless; it limits the strength of conclusions they can support.
Finally, a completed registry entry is not the same as a complete statistical report. This record includes design information and safety counts, but lists zero analyses and does not report the primary outcome estimate or its uncertainty. For biostatisticians and clinical researchers, that gap underscores the value of complete outcome definitions, analysis methods, and transparent reporting of estimates and uncertainty alongside study status.
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 primary limitation for interpreting this specific record is the absence of the primary outcome result. Although change in personal CGM use is named and the assessment times are recorded, the result, its uncertainty, and the analysis method are not reported in the registry record. The exact definition of personal CGM uptake is also not reported, limiting interpretation of what would count as a change.
The single-group design has no concurrent control comparison identified in the registry record. Any observed before-and-after change would therefore be difficult to distinguish from other changes over time. This constrains causal interpretation even if outcome data were available. The registry record does not describe the circumstances around follow-up or whether other care changes occurred.
Other important details are not reported in the registry record: the eligibility criteria used to define high risk or poor control, the analysis population, the amount and pattern of missing outcome data, and the methods used to address missingness. The record also does not provide a statistical analysis plan, a multiplicity strategy, or a sample-size justification for the study. These omissions prevent a full assessment of precision, selection, and the handling of multiple outcomes.
Safety information is limited to group-level affected counts and selected serious-event terms. The record does not provide enough detail to assess event attribution or compare safety with an alternative. The limitations concern what can be interpreted from the registry record; they should not be taken as evidence that unreported procedures or analyses did not occur.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: CGM Use in Poorly Controlled Youth With Type 1 Diabetes — NCT04721145.
- Registry record last updated 2023-08-04; status last verified 2023-07.
- Results first posted 2023-08-04.
- 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.
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18. Record Summary
NCT04721145 is the registry record for IMPaCT, a prospective, single-group study of a 10-day Dexcom G6 continuous glucose monitor trial in high-risk, poorly controlled children with type 1 diabetes. Status is COMPLETED, enrollment is 26, and allocation is listed as NA with masking NONE. The recorded start date is 2021-01-25, and primary completion is 2022-06-28.
The primary outcome is change in personal CGM use at baseline and 3 months. Named secondary outcomes address time in range, hemoglobin A1c, and personal CGM use. The record lists four outcome measures and zero analyses. The primary result, analysis method, and outcome uncertainty are not reported in the registry record.
Safety entries list 5 participants affected by a serious event, 1 affected by an other event, and 0 deaths in the Dexcom G6 group. These entries are descriptive and do not provide a controlled comparison or establish causality.