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 Comparison of Meal-Time Dosing of Insulin in Cystic Fibrosis Related Diabetes (NCT04533646), a na phase 4 study. The primary outcome is Time in Target.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT04533646 |
| Phase | Phase 4 |
| Condition | Cystic Fibrosis-related Diabetes |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 13 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Jagdeesh Ullal |
| Results posted | Yes |
2. Clinical Question
Population
People with cystic fibrosis-related diabetes. The registry records enrollment of 13 participants. It does not report further eligibility details or a defined primary-outcome population.
Intervention
Meal-time rapid-acting insulin dosing by carbohydrate counting, with glucose monitored using a continuous glucose monitor. The registry describes a within-subject comparison of two standard dosing methods.
Comparator
Meal-time rapid-acting insulin given in fixed doses. The listed arm is described as fixed dosing followed by carbohydrate counting; detailed procedures for the sequence are not reported in the registry record.
Primary question
How does percentage of time in the glucose target range compare across the dosing methods? The primary outcome is described as a mean measured over a timeframe of 2 weeks. Numerical results for this comparison are not reported in the registry record.
The study asks whether continuous glucose monitoring can be used to compare glucose excursions under two approaches to meal-time insulin dosing. In the registry summary, the carbohydrate ratio and fixed doses are to be determined using existing doses, total daily insulin doses, body weight, insulin sensitivity, and predisposition to hypoglycemia. These details describe the stated approach; the registry does not provide individual dose values or a full dosing algorithm.
The central statistical feature is that the comparison is described as within-subject: the same participants are intended to contribute information under both methods. That differs from comparing two unrelated groups, because measurements from one participant may be more alike than measurements from different participants. The registry record does not report the numerical glucose results, the estimated difference between methods, or its uncertainty. The study question can therefore be identified, but the posted record does not establish how the measured time in range differed.
3. Trial Design
This completed phase 4 study is registered as a single-group study, with allocation listed as not applicable and masking listed as none. The registry summary describes a within-subject comparison of meal-time rapid-acting insulin dosing by carbohydrate counting versus fixed doses, using continuous glucose monitoring to examine glucose excursions. The record lists enrollment of 13 participants.
The arm description names fixed dosing followed by carbohydrate counting. This indicates a stated sequence in the arm label, but the registry record does not give detailed period procedures, the timing of each dosing approach, or whether the order was varied. It also does not describe a randomized allocation between methods. The registry specifically indicates that the arms are not a like-for-like control comparison, so the arm labels should not be read as randomized parallel groups.
The study is marked completed. The registry lists a primary completion date of 2023-07-31 and a start date of 2020-09-15. These dates describe the record, not the duration of each participant’s exposure to either dosing approach. The primary endpoint timeframe is listed as 2 weeks, but how that timeframe maps to the study periods is not reported in the registry record.
The stated interventions are insulin and a continuous glucose monitor. The registry lists hypoglycemia as a secondary outcome. It does not report the detailed protocol, the method used to analyze the paired observations, the handling of changes in dose or other concurrent care, or the criteria used to determine eligibility for analysis. Those omissions limit how fully the design and resulting comparison can be reconstructed from the registry record alone.
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: Study subjects served as their own controls. There was no wash out or run-in period.
Fixed Insulin Dosing (7 Days)
| Stage | Fixed Dosing, Followed by Carbohydrate Counting |
|---|---|
| STARTED | 13 |
| COMPLETED | 8 |
| NOT COMPLETED | 5 |
Carbohydrate Counting ( 7 Days)
| Stage | Fixed Dosing, Followed by Carbohydrate Counting |
|---|---|
| STARTED | 8 |
| COMPLETED | 8 |
| 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 | Fixed Dosing, Followed by Carbohydrate Counting |
|---|---|---|
| Participants analysed | 13 | |
| Age, Categorical: <=18 years | Participants | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 12 |
| Age, Categorical: >=65 years | Participants | 1 |
| Sex: Female, Male: Female | Participants | 5 |
| Sex: Female, Male: Male | Participants | 8 |
| Race (NIH/OMB): American Indian or Alaska Native | Participants | 0 |
| Race (NIH/OMB): Asian | Participants | 0 |
| Race (NIH/OMB): Native Hawaiian or Other Pacific Islander | Participants | 0 |
| Race (NIH/OMB): Black or African American | Participants | 0 |
| Race (NIH/OMB): White | Participants | 12 |
| Race (NIH/OMB): More than one race | Participants | 1 |
| Race (NIH/OMB): Unknown or Not Reported | Participants | 0 |
| Region of Enrollment: United States | Participants | 13 |
| Baseline weight | pounds | 152 (SD 9) |
6. Primary Endpoint
The registry lists the primary outcome as Time in Target, measured over 2 weeks.
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | Standard Deviation |
| Unit | percentage of time in range |
| Endpoint classification | Continuous Endpoint |
The primary endpoint is titled “Time in Target” and is described as the percentage of time in the glucose target range. The registry characterizes it as a continuous measure summarized by a mean and standard deviation, with a timeframe of 2 weeks. Continuous glucose monitoring is the stated method for examining glucose excursions during the dosing comparison.
Time in range expresses glucose readings as the share of monitored time that falls within a specified target interval. As a general statistical concept, this can summarize many readings into a measure that is easier to compare across periods or participants than a collection of individual readings. It also reflects both the level and pattern of glucose over the monitoring period, rather than a single measurement.
The registry record does not state the numerical boundaries of the target range, how monitor readings were processed, or what minimum amount of monitoring was required. It also does not report the observed mean, standard deviation, comparison estimate, or confidence interval for the primary endpoint. The outcome definition identifies what was intended to be measured, but the posted record does not show the comparative result or its precision.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry describes a clinically focused statistical question: compare time in the glucose target range when participants use fixed meal-time doses and when they use carbohydrate counting. It also describes the comparison as within-subject. In general, measurements from the same participant under two conditions are naturally paired, so an analysis that accounts for that pairing can separate within-person changes from differences between participants. The registry record does not identify whether the reported analysis used a paired method.
Most importantly, numerical results for the primary endpoint are not reported in the registry record. There is no posted mean for either dosing approach, no estimated contrast, and no confidence interval or p-value for the comparison. Without these, readers cannot determine the direction or size of the observed difference, or how precisely it was estimated. The endpoint definition and study description alone do not establish that one method produced a higher or lower time in range.
The registry lists enrollment of 13 participants. In its safety groups, 13 participants are listed as at risk for fixed dosing and 8 for carbohydrate counting. Those safety denominators should not automatically be treated as the number contributing primary-outcome data: the record does not explain why the denominators differ or specify the analysis population for time in range.
The record lists two outcome measures and one analysis, but does not identify the statistical test, model, estimate, or uncertainty used for the primary comparison. It does not report whether results were adjusted for baseline measurements or other factors. The absence of that information prevents readers from checking the analytical assumptions or understanding whether the posted analysis fully reflects the within-subject structure.
A planning section on the page describes sample-size illustrations based on the observed effect, using a two-sided significance level of 0.05, equal allocation, and a normal approximation. These are planning illustrations, not observed power, and the record does not provide a trial-specific sample-size justification. The illustrations cannot substitute for a reported effect estimate and its uncertainty. They also do not resolve the lack of numerical primary results.
The registry reports zero serious adverse events, other adverse events, and deaths in each listed safety group. These are descriptive counts in the record, not an estimate of comparative safety. The different numbers at risk and the absence of further safety details mean the counts should be read as recorded events within those groups, not as proof that event risk was identical between dosing approaches.
Overall, the posted record documents the intended comparison and its outcome measure, but it does not provide the numerical findings needed to interpret the comparative glucose result. Statistical interpretation should therefore remain limited to the study’s question, design, and reported safety counts.
9. Statistical Methods Explained
The registry identifies a continuous primary outcome summarized as a mean and standard deviation. It does not report the test or model used to compare dosing methods, so the methods below explain relevant statistical concepts generally rather than describing a confirmed analysis from this study.
Why the within-subject structure matters
In a within-subject comparison, each participant can contribute observations under both conditions. As a general statistical principle, observations from one person tend to share characteristics, so they should not automatically be treated as independent measurements. A paired analysis focuses on the participant-level contrast between conditions. This can account for stable differences between participants, such as differing underlying glucose patterns. The registry describes the study as within-subject but does not report whether the primary analysis used participant-level pairs, how incomplete pairs were handled, or how many participants contributed data under both methods.
For a paired analysis, the uncertainty of the estimated average contrast depends in part on how variable the within-person differences are. Marginal means and standard deviations for each method alone do not fully describe that variability; the relationship between the two measurements also matters. The record does not provide these numerical outcome summaries or the paired data structure. It is therefore not possible to reproduce or assess a paired estimate from the registry information.
What a mean and standard deviation convey
As a general explanation, the mean summarizes the average outcome across the observations included in an analysis. The standard deviation describes how dispersed those observations are around the mean. These quantities answer different questions: the mean describes the center of the observed values, while the standard deviation describes their spread. Neither one, by itself, gives the uncertainty around a comparison between methods. A confidence interval for a contrast would communicate a range of values compatible with the data and the analysis assumptions. No such interval is reported in the registry record.
Time in range is derived from repeated glucose-monitor readings, while the listed primary summary is a mean. Repeated readings within a participant are not equivalent to independent participants. As a general statistical consideration, analysis should respect the level at which the intervention comparison is made and the repeated nature of the measurements. The record does not state how readings were summarized, whether participant-level summaries were formed first, or whether a model accounted for repeated observations.
Uncertainty, assumptions, and planning
A p-value, when reported, describes how compatible the observed data are with a specified null model under the assumptions of the test. It does not by itself show the size or practical importance of an effect. A confidence interval is useful alongside an estimate because it conveys the range of values consistent with the data and model. Neither a p-value nor a confidence interval for the primary comparison is reported in the registry record, so no inference about statistical significance or precision can be drawn from the posted entry.
The sample-size section uses planning illustrations based on the observed effect. The stated assumptions are a two-sided significance level of 0.05, equal allocation, and a normal approximation; the effect to detect is a stated fraction of the observed effect. These figures, where displayed on the page, are planning scenarios rather than observed power. They are not evidence that the trial was designed around those assumptions, and they do not establish that the study had adequate precision. The registry record does not report a trial-specific sample-size justification.
General statistical methods may also need to account for over-dispersion when observed variability is greater than a model assumes. Greater variability can make estimates less precise if it is not accommodated. The registry does not report a model or distributional assessment for this outcome, so there is no basis for saying whether over-dispersion was present or relevant to the analysis conducted.
What cannot be reconstructed
The registry lists one analysis but does not identify its method, covariates, analysis population, or handling of missing monitor data. It does not give the target-range boundaries or detailed rules for valid monitoring. Without those elements and the numerical results, readers cannot independently reproduce the primary comparison or evaluate its assumptions. These are limits of the information available in the registry record, not evidence that a particular method was or was not used.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists a primary outcome, time in the glucose target range, and hypoglycemia as a secondary outcome. It also lists two outcome measures and one analysis. The record does not explain how the secondary outcome was defined, whether additional comparisons were planned, or how multiplicity across outcomes or analyses was handled. It does not report a hierarchy of hypotheses or whether any adjustment was made.
Multiplicity is a general statistical concern when several outcomes or comparisons are tested: the chance of at least one apparently notable result can increase as more tests are considered. Whether and how that concern applies cannot be determined from the registry description. The single listed analysis should not be taken to mean that only one analysis was conducted; the analysis details are not reported in the registry record.
Missing data are also important for continuous glucose-monitor outcomes. As a general principle, missing readings or incomplete monitoring can affect which observations contribute and may affect the interpretation if the missingness is related to glucose patterns or study conditions. The registry does not state how missing readings, incomplete monitoring periods, or participants without measurements under both methods were handled. It also does not describe imputation or sensitivity analyses.
The analysis population is not defined. The registry lists 13 enrolled participants, while the safety table lists 13 at risk for fixed dosing and 8 for carbohydrate counting. Those figures do not establish which participants were included in the primary analysis, and the record does not explain the different safety denominators. No intention-to-treat, per-protocol, or other analysis-population definition is reported in the registry record.
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 |
|---|---|---|---|
| Fixed Dosing | 0 | 13 | 0.0% |
| Carb Counting | 0 | 8 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Fixed Dosing | 0 of 13 |
| Carb Counting | 0 of 8 |
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 |
|---|---|
| Fixed Dosing | 0 of 13 |
| Carb Counting | 0 of 8 |
The registry safety table lists 13 participants at risk in the fixed-dosing group and 8 at risk in the carbohydrate-counting group. It records zero serious adverse events, zero other adverse events, and zero deaths for each group. These are the counts shown in the posted safety information.
The at-risk numbers are not the same across the listed groups. The registry does not explain the reason for that difference or how participants were assigned to each safety group. In a within-subject study, safety-group counts should not be assumed to represent independent parallel cohorts. The table also does not provide additional detail about event monitoring or the criteria used to classify events.
Zero recorded events in these groups means that the registry table reports no events of those types for the listed denominators. It does not establish that the risk of an event is zero, nor does it provide a precise comparison of risk between dosing methods. The small enrollment and differing denominators further limit what can be inferred from these descriptive counts. The safety figures should be read as registry-reported observations, not as a comparative estimate or a conclusion about safety.
12. What the Result Does, and Does Not, Mean
This study addresses how time in the glucose target range compares when people with cystic fibrosis-related diabetes use fixed meal-time insulin doses versus carbohydrate counting. Its stated within-subject approach is relevant because each participant may contribute information under both methods, allowing the comparison to account for stable differences between people if the analysis is structured appropriately.
The registry record does not report numerical results for the primary endpoint. It therefore does not show whether time in range was higher, lower, or similar between the dosing approaches, and it does not quantify the precision of any difference. The endpoint description, study completion status, and safety counts cannot substitute for an outcome estimate.
The record also does not establish that the methods were compared in randomized order or that the listed groups function as equivalent control groups. It describes a single-group, unmasked study and names the sequence as fixed dosing followed by carbohydrate counting. Detailed procedures are not reported. As a general design consideration, a non-randomized sequence can make it harder to distinguish method-related changes from changes over time or other period effects; the registry does not show whether these issues were assessed.
Accordingly, the posted information supports a description of the research question, design, endpoint, and recorded adverse-event counts. It does not support a conclusion that either dosing method is better or worse, or a conclusion about the size of any difference. Those conclusions would require numerical outcome results and sufficient information about the analysis and its uncertainty.
13. Why This Trial Matters Statistically
This trial is statistically notable because it frames the comparison within participants rather than as a simple comparison of two unrelated groups. For a continuous glucose-monitoring outcome, the way repeated readings are summarized and linked to each participant can affect the estimate and its uncertainty. A clear account of pairing and data handling is therefore important for understanding the comparison.
The primary endpoint, percentage of time in the glucose target range, condenses a stream of monitor readings into a participant-level measure. That can make results easier to communicate, but interpretation depends on details such as the target boundaries, valid-monitoring rules, and analysis timeframe. Those details are not reported in the registry record. Nor are the numerical endpoint results, so the central comparative question remains unanswered in the posted information.
The record also illustrates why design labels and analysis details matter. It is marked single group, unmasked, and not randomized, while the summary describes a within-subject comparison. These features do not make the research question unimportant; they mean that readers need the sequence, period, and analysis details to assess how securely an observed change could be attributed to the dosing method. Those details are not reported in the registry record.
Finally, the safety table contains zero events in the listed groups, but the differing at-risk counts and absence of further context prevent a strong comparative interpretation. Statistical reporting is most useful when outcome estimates, uncertainty, denominators, and methods appear together. Here, the registry makes the intended question clear but leaves those elements incomplete.
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 registry record gives limited detail about the study procedures. Although the summary describes a within-subject comparison and the arm label names fixed dosing followed by carbohydrate counting, it does not describe the period schedule, whether sequence variation was possible, or how long each method was used. The primary endpoint timeframe is 2 weeks, but its relationship to the dosing periods is not explained.
The study is listed as single group, with allocation not applicable and no masking. The registry also indicates that the arms are not a like-for-like control comparison. Without detailed procedures and an analysis that accounts for the within-subject structure, the interpretation of any comparison would be difficult to assess. The registry record does not report whether period effects or other time-related changes were considered.
Enrollment is listed as 13, and the safety table gives different at-risk counts for the two dosing groups. The record does not explain the difference or state how many participants contributed complete primary-outcome data. It also does not report a participant flow, missing-monitoring rules, the target-range boundaries, or the analysis population.
Numerical primary-outcome results and their uncertainty are not reported in the registry record. The statistical method, sample-size justification, and any multiplicity or sensitivity procedures are also not described. These information gaps prevent evaluation of the magnitude, precision, and robustness of the comparison. They should be distinguished from evidence that a particular result or analysis was absent from the study itself; the registry entry does not provide enough detail to determine that.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Comparison of Meal-Time Dosing of Insulin in Cystic Fibrosis Related Diabetes — NCT04533646.
- Registry record last updated 2025-10-15; status last verified 2025-10.
- Results first posted 2025-03-19.
- 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 phase 4, single-group study of meal-time rapid-acting insulin dosing in cystic fibrosis-related diabetes. Its summary frames a within-subject comparison of fixed dosing with carbohydrate counting, using continuous glucose monitoring. Enrollment is listed as 13, masking as none, and allocation as not applicable.
The primary outcome is mean percentage of time in the glucose target range over a timeframe of 2 weeks. Hypoglycemia is listed as a secondary outcome. The numerical primary results, statistical comparison method, analysis population, missing-data approach, and trial-specific sample-size justification are not reported in the registry record.
The safety table records zero serious adverse events, zero other adverse events, and zero deaths in each listed group, with different numbers at risk. These are descriptive counts, not a comparative safety estimate. The record identifies the research question and design, but does not provide enough numerical outcome information to interpret the primary comparison.