Diabetes Prevention Program in Youth: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Diabetes Prevention Program in Youth (NCT03042936), a na na study. The primary outcome is Change From Baseline Hemoglobin A1c.

2. Clinical Question

The clinical question is therefore about what happened to the primary outcome among participants who took part in the curriculum, not whether the curriculum outperformed a comparison treatment. Because no numerical outcome result is reported, even the within-group change cannot be described from the registry record.

3. Trial Design

This completed study evaluated the Insulin Superheroes Club Curriculum in a single group. The registry records enrollment of 33 participants, lists allocation as NA, and records masking as NONE. It does not describe a randomized allocation or a separate control group. As a result, the design is not a like-for-like comparison of the curriculum against an alternative.

The brief description identifies an out-of-school diabetes prevention program for youth ages 7-15 with a family history of pre-diabetes or type 2 diabetes. The intervention is classified as behavioral. The official title describes the program as a 12-month supplement to the CDC DPP for Adults, while the primary outcome timeframe is 16 weeks. The registry record does not explain how these durations relate to each other or specify when each participant began or completed the curriculum.

The listed primary outcome is change from baseline in hemoglobin A1c, summarized by a median and inter-quartile range at 16 weeks. Secondary outcomes include changes in body mass index Z-score, waist circumference Z-score, systolic and diastolic blood pressure Z-scores, percent body fat, total cholesterol, LDL cholesterol, and HDL cholesterol. The record lists 17 outcome measures, but does not provide numerical efficacy results or analysis counts beyond recording 0 analyses.

The study start is recorded as 2015-03, primary completion as 2020-11-04, and overall status as COMPLETED. The registry does not report the sample-size justification, detailed eligibility rules, recruitment flow, intervention fidelity, follow-up procedures, or a fuller statistical analysis plan. These omissions limit what can be concluded about implementation and the handling of the outcome data.

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

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 Change From Baseline Hemoglobin A1c, measured over 16 weeks.

Hemoglobin A1c reflects the proportion of hemoglobin with glucose attached and is commonly used as an indicator of average blood glucose over a period of time. The registered primary endpoint is change from baseline in this measure, expressed in A1c percentage points. The outcome is intended to describe whether and how the measure shifted between baseline and the 16-week assessment among participants in the study.

Change from baseline can be useful because it focuses on within-participant movement rather than only on the value measured at follow-up. In a single-group study, however, that change does not by itself separate an intervention effect from other explanations, such as changes over time, measurement variability, or factors occurring alongside the program. This is a general limitation of interpreting uncontrolled before-and-after data.

The registry specifies the median as the summary measure and the inter-quartile range as its dispersion measure. In general, the median describes the middle of the observed values, while the inter-quartile range describes the spread of the central portion of those values. These summaries can be informative when distributions are skewed or include extreme values. The registry record does not report the median change, its inter-quartile range, the number contributing data at 16 weeks, or a confidence interval. The endpoint therefore cannot be quantitatively interpreted from the registered results.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

Several statistical ideas help clarify what the registry record can and cannot show. The study lists a continuous primary outcome: change in hemoglobin A1c, expressed in A1c percentage points. The registry specifies a median and inter-quartile range, rather than a mean and standard deviation. The numerical summaries themselves are not reported in the registry record.

What does a median and inter-quartile range describe?

In general, the median is the middle value after observations are ordered. The inter-quartile range describes the spread between the central lower and upper portions of the ordered observations. Unlike the mean, the median is less influenced by a small number of unusually large or small values. This can make it a useful summary when a distribution is asymmetric or contains outliers. The inter-quartile range conveys dispersion, but it does not show every feature of the distribution or identify individual participant trajectories.

The record does not report whether the median and inter-quartile range were calculated from individual change scores or through another approach, nor does it identify the method used to estimate uncertainty. It gives no confidence interval or hypothesis-test result for the primary endpoint. A median and an inter-quartile range, without their values and without information about the analysis, are not enough to determine the direction or precision of the result.

What does change from baseline mean in a single group?

As a general statistical concept, a change score compares a participant's measurement at follow-up with that participant's baseline measurement. A summary of these changes describes what happened within the observed group. It is not equivalent to a between-group treatment contrast. This study is recorded as single-group, and allocation is listed as NA. There is no registered comparator against which to estimate a difference in changes.

In a randomized comparison, the difference between groups can help account for changes that would also have occurred without the intervention, subject to the design and analysis assumptions. In a single-group before-and-after study, no concurrent group provides that reference. Changes over time, regression to the mean, measurement error, and other experiences during follow-up are general alternative explanations for a within-group change. The registry record does not report methods that would isolate the curriculum's contribution.

Why does dispersion matter?

Dispersion indicates how similar or different participants' results are. A central summary alone can conceal wide variation: a group median may coexist with participant changes in different directions. The inter-quartile range can give a view of the spread among central observations, but the record does not contain its numerical value. In general, a wide spread makes a single summary less representative of every participant, while a narrow spread suggests the central observations are more alike. Neither pattern, by itself, establishes a causal effect.

For count outcomes, over-dispersion is a general concern when variation exceeds what a simple model assumes. It can make conventional uncertainty estimates too small if not handled appropriately. That concept is not directly identified as an issue for this continuous primary endpoint, and the registry does not report a model or over-dispersion assessment. No conclusion about the analysis method can be drawn from the endpoint summary designation alone.

What can a confidence interval add?

In general, a confidence interval communicates uncertainty around an estimated effect under a specified statistical procedure and its assumptions. A narrow interval indicates greater precision than a wide interval, though precision is not the same as clinical importance. For a single-group change, an interval would quantify uncertainty about the within-group estimate; it would not create the missing control comparison or remove the design's limitations. The registry record does not report a confidence interval for the primary endpoint.

A p-value, in general, measures how incompatible the observed data are with a stated null model, under the analysis assumptions. It does not measure the probability that the intervention works, nor does it convey the size or practical importance of an effect. No p-value or inferential test for the primary outcome is reported in the registry record, so no significance claim can be made.

How should planning illustrations be distinguished from study results?

General sample-size illustrations use assumptions about a target effect and analysis design to show the number of participants per arm that might be needed for a chosen power target. The stated illustration assumptions use a two-sided significance level of 0.05, equal allocation between two arms, a normal approximation, and an effect defined as a fraction of the observed effect. Such calculations are planning illustrations, not observed power and not a description of the actual trial design.

That distinction is especially important for this study because the registry records a single group, not a two-arm comparison. The illustration assumptions do not establish that the study was designed with two arms, and they are not a justification for the enrollment of 33 participants. The registry record does not report the trial's own sample-size justification. Since the observed primary effect is not numerically reported, the assumptions alone also do not permit an independent assessment of the target effect used in any illustration.

Overall, the registry names the primary measure and its summary format but does not report the estimate, uncertainty, model, hypothesis test, or analysis population. General statistical methods can explain the meaning of those elements, but cannot fill in values or procedures that are absent from the record.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists a primary outcome and numerous secondary measures, but does not report a detailed plan for controlling multiplicity. Multiplicity arises when multiple outcomes, timepoints, or statistical tests are examined: the more opportunities there are to identify an apparently unusual result, the greater the chance of a misleading finding if all tests are interpreted without accounting for that process. This is a general statistical concern, not evidence that a particular adjustment was or was not used in this study. Any multiplicity procedure is not reported in the registry record.

The record names secondary changes in body mass index Z-score, waist circumference Z-score, systolic and diastolic blood pressure Z-scores, percent body fat, and cholesterol measures. It does not provide their numerical results, test results, or a hierarchy of confirmatory and exploratory outcomes. The number of listed outcome measures is 17, but that count does not establish how many were analyzed or how their results were interpreted. The record lists 0 analyses.

Missing-data handling is also not reported in the registry record. The enrollment count is 33, but the record does not state how many participants had baseline and 16-week A1c measurements, whether follow-up was incomplete, or why any data may have been missing. It does not describe imputation, complete-case analysis, or sensitivity analyses. In general, missingness can affect results if the availability of an outcome is related to participants' characteristics or outcomes.

The definition of the analysis population is not reported in the registry record. It is therefore unclear which participants would be included in any endpoint summary and how deviations from the intended intervention or incomplete follow-up were handled. These omissions prevent assessment of whether missing outcomes or multiple comparisons could have influenced the reported findings; moreover, the numerical findings themselves are not posted.

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.

The registry records 33 participants at risk for serious adverse events and 0 affected. It also records 33 participants at risk for other adverse events and 0 affected. The death count is 0, and no top serious adverse event terms are listed. These are the safety figures recorded for the Insulin Superheroes Club Curriculum group.

In general, an at-risk count identifies the group against which the reported event count is understood; an affected count is the number recorded with an event in that category. The recorded zero counts mean that the registry lists no participants as affected in these categories. They do not establish that no symptoms or experiences occurred outside the registry's adverse-event definitions, collection procedures, or reporting period. Details about how events were collected, defined, monitored, or assessed are not reported in the registry record.

These figures should be read as descriptive safety reporting, not as a comparison of risk between treatments. The study is single-group and has no registered comparator, so there is no parallel group for estimating a relative difference in adverse events. The record also does not supply detail about exposure duration for safety monitoring or participant-level follow-up. The figures therefore describe what is registered, but do not establish a comparative safety profile.

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

The registry record documents a completed single-group study of the Insulin Superheroes Club Curriculum for youth ages 7-15 with a family history of pre-diabetes or type 2 diabetes. It identifies change from baseline in hemoglobin A1c at 16 weeks as the primary endpoint and specifies that results would be summarized by a median and inter-quartile range. It also records enrollment of 33 participants and lists a range of secondary measures.

Those design and outcome descriptions do not reveal the observed primary result. The registry record does not report the median A1c change, its inter-quartile range, or an uncertainty estimate. It therefore cannot show whether the measure changed, how large any change was, or how consistently participants changed. The same absence of numerical findings applies to the listed secondary outcomes.

Even if a within-group change were available, it would not by itself show that the curriculum caused the change. As a general principle, changes in a single group can reflect the intervention or other influences over time. With no registered control group, the record cannot provide a direct estimate of what would have happened to a comparable group without the curriculum.

The outcome choice is clinically recognizable as a measure related to average blood glucose, but a registry outcome description is not evidence of a favorable or meaningful result. Clinical importance requires interpreting the size and uncertainty of an estimate in context; neither is available for the primary endpoint in this record. The completed status likewise does not indicate that the intervention achieved a particular outcome.

The most supportable conclusion is limited: the registry describes a behavioral youth program, a single-group design, and a planned primary measure, but does not post the numerical efficacy results needed to characterize the observed change. No conclusion that the curriculum did or did not alter A1c, or that any change was attributable to the curriculum, follows from the information recorded.

13. Why This Trial Matters Statistically

This study is statistically informative as an example of why a clearly named endpoint is not enough to interpret trial findings. The record specifies a primary measure, the summary statistic, its dispersion measure, and its timeframe. Those elements identify what the investigators intended to assess, but without numerical results they cannot establish the direction, magnitude, or precision of the outcome.

The single-group design also illustrates the difference between describing change and estimating a comparative intervention effect. A within-group change can characterize participants' observed course, but a control group is generally needed to distinguish the intervention contrast from other changes over time. The record lists no randomized comparison and no separate comparator, so causal interpretation is limited even apart from the missing outcome values.

The registry includes a broad set of secondary outcomes. In general, multiple outcomes can create interpretive challenges because findings across many measures may not carry the same evidential status as a prespecified primary analysis. A statistical analysis plan can clarify outcome hierarchy, missing-data handling, and multiplicity procedures; those details are not reported in the registry record.

The contrast between the registered endpoint timeframe of 16 weeks and the official title's reference to a 12-month supplement also shows why timing details matter. The record does not explain their relationship, so readers should not assume that the primary endpoint was measured at the end of the titled program period.

Finally, the registry's safety counts are descriptive and come from a single group. They offer no comparative risk estimate. Taken together, the record highlights the importance of complete outcome reporting, transparent analysis methods, and design features that support a well-defined comparison. These are general statistical lessons; the record itself does not supply evidence about the size or cause of any outcome change.

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.

Several limitations specific to this record constrain interpretation. First, it records a single-group design with allocation listed as NA and masking as NONE. There is no registered control group, so the study cannot provide a direct comparison with another intervention or with no intervention. Any reported within-group change would have to be interpreted without that comparative reference.

Second, the numerical primary result is not reported in the registry record. The median change in hemoglobin A1c, its inter-quartile range, and measures of uncertainty are absent. The record also does not post numerical results for the listed secondary outcomes. This prevents assessment of effect direction, size, variability, or precision.

Third, the relationship between the official title's 12-month description and the primary outcome timeframe of 16 weeks is not explained. The record does not specify the timing of other assessments or provide enough information to determine whether the primary outcome was assessed during or after the titled program period.

Fourth, the registry does not report how many of the 33 enrolled participants contributed measurements to the primary endpoint, how missing data were handled, or how the analysis population was defined. It also does not report the sample-size justification, detailed eligibility criteria, participant characteristics, or the statistical analysis plan. The number of analyses is listed as 0, which leaves no posted analytic results to evaluate.

Finally, safety reporting is limited to event counts and at-risk counts, without further detail on collection methods or follow-up. These limitations are specific to what is recorded; they do not establish that the underlying study lacked procedures or analyses. They mean those procedures and results are not reported in the registry record.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Diabetes Prevention Program in Youth — NCT03042936.
• Registry record last updated 2023-11-22; status last verified 2020-11.
• Results first posted 2023-11-22.
• 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 the completed Insulin Superheroes Club Curriculum study, a behavioral, single-group diabetes prevention program for youth ages 7-15 with a family history of pre-diabetes or type 2 diabetes. Enrollment is recorded as 33; allocation is NA and masking is NONE.

The primary endpoint is change from baseline in hemoglobin A1c, expressed in A1c percentage points and assessed at 16 weeks. The registry specifies a median and inter-quartile range, but does not report the numerical outcome or its uncertainty. Secondary measures include body composition, blood pressure, and cholesterol outcomes; their numerical results are also not reported in the registry record.

The safety record lists 0 serious adverse events, 0 other adverse events, and 0 deaths among the recorded group. With no registered comparator and no posted efficacy estimates, the record supports description of the study design and intended measures, but not a conclusion about the size or cause of an outcome change.