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 Sugar-replacement Sweeteners, and Blood Sugar Control (NCT01128829), a randomized na study. The primary outcome is The Effect of Sucralose on Insulin Concentration (Area Under the Curve; AUC).
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT01128829 |
| Phase | NA |
| Condition | Obesity |
| Allocation | Randomized |
| Design model | Crossover |
| Masking | None (open label) |
| Enrollment | 17 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Washington University School of Medicine |
| Results posted | Yes |
2. Clinical Question
Population
The registry describes participants with obesity who were not regular users of non-nutritive sweeteners. Enrollment is listed as 17. The record does not provide further participant characteristics or a more detailed eligibility description.
Intervention
Participants drank sucralose in water 10 minutes before a glucose load during a modified oral glucose tolerance test. The intervention description identifies sucralose as the sweetener being studied.
Comparator
The comparison was an equal volume of water without sucralose, also taken 10 minutes before the glucose load. The study used a crossover design, so participants received both conditions on separate test occasions, in randomized order.
Primary question
The primary outcome was insulin concentration area under the curve during the test. The research question was whether insulin exposure over the testing period differed between the sucralose and water conditions. Although the study description also discusses incretin release and appetite-related substances, the registry record does not report results for those measures.
The study was intended to examine the body's blood-sugar regulation response after a glucose load when preceded by a non-caloric sweetener or water. Its primary measure was the aggregate insulin response over time, not a direct measure of blood glucose control in everyday settings. The registry describes the assessment procedure, but does not report the numerical insulin AUC result, the estimated difference between conditions, or a measure of uncertainty. Consequently, the record does not establish the direction, size, or precision of a contrast between the two conditions.
3. Trial Design
The registry identifies this as a randomized, unmasked crossover study sponsored by Washington University School of Medicine. It lists the study status as completed, enrollment as 17, and phase as NA. The record gives a start date of 2010-05 and a primary completion date of 2012-02.
Participants completed two oral glucose tolerance tests. One sequence had water before the first test and sucralose before the second; the other sequence reversed that order. In each condition, the drink was taken 10 minutes before the glucose load. The two tests were separated on average by approximately 1 week, described in the record as a washout interval.
A crossover design compares conditions within participants rather than assigning each participant to only one condition. In general, this can make a within-person contrast useful because each participant experiences both conditions. Interpretation depends on design and analysis details, including whether order, period, and possible carryover effects are appropriately considered. The registry record does not report the statistical model or the analysis method used for these features, so it is not possible to determine how they were addressed.
The study was unmasked, meaning the registry does not describe masking of participants or study personnel. The record does not report concealment procedures, a detailed randomization method, or the allocation ratio. Nor does it report a protocol-based sample-size justification or interim-analysis plan. These omissions do not establish that such procedures were absent; they mean that the details are not reported in the registry record.
4. Participant Flow and Accounting
The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.
Overall Study
| Stage | "Water Then Sucralose" | "Sucralose Then Water" |
|---|---|---|
| STARTED | 6 | 11 |
| COMPLETED | 6 | 11 |
| NOT COMPLETED | 0 | 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 | Obese Non Regular Users of Non Nutritive Sweeteners (NNS) |
|---|---|---|
| Participants analysed | 17 | |
| Age, Continuous | years | 35.1 (SD 4.1) |
| Sex: Female, Male: Female | Participants | 15 |
| Sex: Female, Male: Male | Participants | 2 |
6. Primary Endpoint
The registry lists the primary outcome as The Effect of Sucralose on Insulin Concentration (Area Under the Curve; AUC), measured over Baseline.
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | Standard Deviation |
| Unit | (pmol • min •L-1) |
| Endpoint classification | Continuous Endpoint |
The primary endpoint is the effect of sucralose on insulin concentration area under the curve, with the unit recorded as (pmol • min •L-1). Insulin concentrations were measured during a 5-hour modified oral glucose tolerance test after participants consumed sucralose in water or an equal volume of water without sucralose. The record describes measurements before and after ingestion of 75g of glucose and says the collected measurements were used to create an AUC curve.
In general, area under the curve condenses measurements taken over time into a measure of cumulative response across the specified observation period. It can describe overall exposure without treating each measurement time as a separate primary endpoint. It does not, by itself, show when a response occurred or whether the time profile differed between conditions. Those questions require additional analyses or presentation of the repeated measurements.
The registry labels the timeframe as Baseline, although its description concerns measurements during the test after the drinks and glucose load. The record does not clarify that label. It also does not report the insulin AUC values, a between-condition estimate, a confidence interval, or a test result. Therefore the endpoint is identifiable, but its observed result and precision are not reported in the registry record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The record specifies a randomized comparison of two pre-test drinks in a crossover design and identifies insulin AUC as the primary outcome. It does not provide the outcome data needed to describe whether the observed insulin response was higher, lower, or similar under either condition. The insulin AUC estimate, a contrast between conditions, an uncertainty interval, and a statistical test result are not reported in the registry record.
Without an estimated contrast and a measure of precision, the clinical and statistical interpretation of the primary outcome is limited. A point estimate would indicate the observed direction and magnitude of the comparison, while an interval estimate would show how uncertain that estimate is under the analysis. A test result alone, even if available, would not convey the size or practical importance of a difference. Neither kind of result is reported in the record, so no conclusion about the outcome's direction or precision can be drawn from it.
The crossover structure means that the natural comparison is within participants, with each participant undergoing both conditions in randomized sequence. General interpretation of a crossover estimate depends on the handling of sequence and test period, as well as the possibility that one condition could influence measurements in a later period. The registry record describes the order sequences and approximate washout, but does not report whether these issues were assessed or how they entered the analysis. It is therefore not possible to characterize the analysis as adjusted or unadjusted for period or carryover effects.
The registry lists one outcome measure and one analysis. That description does not disclose the analysis model, the tested contrast, the treatment of repeated measurements, or the handling of incomplete data. The record also does not report an analysis population or details about exclusions. Those omissions matter because results from a crossover trial depend on which participants and periods contribute to the comparison and on how within-participant dependence is handled.
The registry's planning description refers to sample-size illustrations based on an observed effect, using a two-sided significance level of 0.05, equal allocation, and a normal approximation. Such illustrations are planning tools, not observed power. The numerical planning outputs and the observed effect are not reported in the registry record. They therefore cannot fill the gap left by the missing endpoint result or establish how precisely the study estimated the contrast.
The safety listing reports zero serious adverse events and zero other adverse events for the listed group, with 17 at risk in each category. Deaths are recorded as null, which is not the same as a reported count of zero. These entries should be read as registry safety reporting, not as evidence about the insulin outcome. Overall, the record documents the question, design, and planned endpoint, but does not provide a numerical efficacy result or enough statistical detail to evaluate its estimation.
9. Statistical Methods Explained
What does a crossover comparison estimate? In general, a crossover study exposes participants to each study condition at different periods, with the order randomized. The comparison can use the within-participant change or contrast, which accounts for stable differences between participants. Here, the registry describes a water-then-sucralose sequence and a sucralose-then-water sequence. It does not report the estimator or statistical model used to compare the conditions.
Repeated outcomes from the same participant are statistically dependent: measurements from one participant tend to share characteristics that measurements from different participants do not. A suitable analysis generally needs to reflect this dependence. Treating every measurement as independent can understate uncertainty. The registry record does not specify whether the analysis used a paired method, a repeated-measures model, or another approach, so the method used cannot be identified.
Why can test order and period matter? In general, a period effect occurs when outcomes differ by testing occasion for reasons apart from the assigned condition. A carryover effect occurs when exposure in an earlier period influences a later period's outcome. Randomizing sequence can help balance order, while a washout interval is intended to allow earlier effects to dissipate. The record reports an average separation of approximately 1 week between tests, but does not report a diagnostic assessment or analysis of period or carryover effects. The description alone cannot confirm whether the interval was sufficient for this outcome.
What does the AUC summarize? Area under the curve combines measurements across an observation interval into an aggregate measure of response. For this study, the outcome is insulin concentration AUC during the modified glucose tolerance test. In general, an AUC can be useful when the overall response over time is the target, rather than a single time point. It can also conceal distinct response patterns: two conditions could have similar aggregate areas despite differing at particular times. The registry does not report the individual time-course results or explain the precise AUC calculation method.
The endpoint description lists insulin measurements before and after the glucose load, and says all collected data were used to create the AUC curve. It does not state whether the area was calculated by a particular numerical rule, whether baseline correction was applied, or how missing measurements would affect calculation. These are methodological details that can affect an AUC estimate; their status is not reported in the registry record.
How should an estimate and its uncertainty be read? In general, an estimated contrast summarizes the observed difference between conditions according to the chosen analysis. A confidence interval describes uncertainty around that estimate under the model and assumptions used. A narrow interval indicates greater precision than a wide interval, but neither the estimate nor its interval alone determines whether a difference is clinically important. The record does not report an estimated contrast, confidence interval, standard error, or p-value for the primary endpoint.
A p-value, in general, measures how compatible the observed data are with a specified null hypothesis under the assumptions of a statistical test. It is not the probability that the null hypothesis is true, and it does not measure the size or importance of an effect. Because no primary-outcome test result or hypothesis-testing details are reported, a p-value interpretation is not possible for this record.
What does over-dispersion mean in general? For count outcomes, over-dispersion means that variability is greater than a model's basic assumptions allow. It can make standard errors too small if ignored, affecting confidence intervals and tests. This trial's primary outcome is continuous insulin AUC, not a count endpoint, so over-dispersion is not a direct description of the primary measure. Regardless of outcome type, the selected model should reflect the data structure and variability. The registry does not report the model or its diagnostic checks.
The registry's planning assumptions describe an illustration using a two-sided significance level of 0.05, equal allocation, and a normal approximation, with the target effect expressed as a fraction of the observed effect. In general, planning calculations ask what sample size could be needed to detect a specified effect under stated assumptions. They are not a measure of the probability that the completed study detected an effect, and they are not observed power. The record does not report the numerical planning outputs, and no observed primary effect is reported there for comparison.
Finally, the record lists one outcome measure and one analysis. That is not enough to establish the analysis was prespecified, to identify whether adjustment for multiple comparisons was considered, or to tell whether any additional exploratory analyses were conducted. Statistical methods, model assumptions, and sensitivity analyses are not reported in the registry record. As a result, the study design is described more fully than the analysis used to produce a primary-outcome estimate.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists one outcome measure and one analysis. This gives a limited account of the scope of the reported analysis, but does not establish that only one outcome was collected or only one analysis was conducted. The record does not report a multiplicity strategy, such as whether any adjustment was planned for multiple outcomes, time points, or contrasts. It also does not specify which comparison was used for the single listed analysis beyond identifying the insulin AUC endpoint.
The analysis population is not reported in the registry record. The enrollment entry is 17, but the record does not say how many participants completed both test periods, contributed to the primary analysis, or were excluded. It does not describe an intention-to-treat, per-protocol, or other population definition.
Missing-data methods are also not reported. The registry does not explain whether all scheduled insulin measurements were available, how incomplete test sessions were handled, or whether any imputation or sensitivity analysis was used. In a crossover study, missing data in either period can affect which within-participant comparisons are available. Without these details, the completeness and representativeness of the analyzed outcome cannot be assessed from the registry record.
These are reporting gaps, not evidence that a particular method was or was not used. The record does not describe a statistical analysis plan, so the prespecified status of the listed outcome and analysis is also not 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 |
|---|---|---|---|
| Obese Non Regular Users of Non Nutritive Sweeteners (NNS) | 0 | 17 | 0.0% |
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 |
|---|---|
| Obese Non Regular Users of Non Nutritive Sweeteners (NNS) | 0 of 17 |
The registry lists a group titled “Obese Non Regular Users of Non Nutritive Sweeteners (NNS).” For that group, 17 are listed at risk for serious adverse events and zero are listed as affected. The separate other-adverse-event entry also lists 17 at risk and zero affected. These are the registry's reported counts; the entries do not provide descriptions of event monitoring or attribution to a particular study condition.
The deaths entry is null. A null value should not be read as a numerical count of zero: it means a death count is not reported in that field. The registry record does not list serious adverse-event terms for the study.
These safety entries are distinct from the primary insulin AUC outcome. They do not establish the absence of all possible adverse effects or explain how adverse events were collected. The record does not report further detail about event definitions, observation windows, or the relationship between events and the study drinks. The counts should therefore be interpreted narrowly as the safety information entered in the registry.
12. What the Result Does, and Does Not, Mean
The record establishes that a randomized crossover study compared sucralose in water with water before a glucose load and identified insulin concentration AUC as its primary outcome. It also describes the testing procedure, the two sequence orders, and the approximate interval between tests. These details clarify what question the design was intended to address.
The record does not report the outcome estimate or its uncertainty. It therefore does not show the direction or size of the insulin AUC contrast, how precise an estimate was, or whether the analysis found evidence of a difference. No claim that either condition increased, decreased, or had no effect on the primary endpoint can be supported by the registry results. The study's stated hypothesis is not itself evidence that the predicted response occurred.
The measured endpoint is an insulin response during a controlled glucose tolerance test. In general, such a measure is specific to the test conditions and observation period. It does not, on its own, establish effects on long-term blood sugar control, everyday dietary behavior, clinical outcomes, or other populations. The registry describes participants with obesity who were not regular users of non-nutritive sweeteners; generalization beyond that described group cannot be evaluated from the available record.
The study description mentions incretin release and appetite-affecting substances as research interests, but the listed primary endpoint is insulin AUC. The record does not report results for incretin or appetite-related outcomes. Nor does it provide the statistical analysis details needed to assess period effects, missing observations, or model assumptions.
Thus, the trial record is informative about the study question and structure, but it is not sufficient to judge the primary result. The absence of a reported result should not be interpreted as evidence for either similarity or difference between conditions.
13. Why This Trial Matters Statistically
This trial is statistically notable for its within-participant crossover structure. In general, when the same participant experiences both conditions, comparisons can account for stable participant characteristics that might otherwise contribute to between-person variability. The design also makes sequence and period important: outcomes can depend on testing order or on effects that persist from an earlier condition. The registry describes randomized sequences and an approximate washout, but does not report how the analysis handled these features.
The endpoint illustrates why repeated measurements can be summarized using an area under the curve. Insulin was measured across the modified glucose tolerance test, and AUC represents the overall response over that interval. As a summary, it can be useful for a question about aggregate response, while still obscuring details of the response at individual times. The registry does not provide the AUC values or time-specific results, so neither the aggregate contrast nor its time course can be assessed.
The record also illustrates the distinction between a completed study and a fully interpretable result. It reports enrollment, a primary outcome, and a design, but does not report the endpoint estimate, uncertainty, analysis population, or statistical model. Those elements are needed to judge both magnitude and precision, and to understand how the crossover data were analyzed.
Finally, planning illustrations are conceptually different from evidence generated by the completed analysis. The registry describes planning assumptions, but they do not substitute for an observed treatment contrast or its uncertainty. Because the numerical outcome and planning results are not reported in the registry record, the available statistical information supports a description of the intended comparison, not a quantitative conclusion about its result.
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 trial record is that the insulin AUC result is not reported. No condition-specific values, estimated contrast, confidence interval, standard error, or test result are available in the registry record. As a result, the direction, magnitude, and precision of the primary comparison cannot be assessed.
The registry identifies a crossover design and the two randomized sequences, but does not give the statistical model or describe how participant-level dependence, testing period, sequence, or possible carryover were handled. The approximate washout is reported, but its adequacy for the outcome cannot be established from the description alone.
Further analytic details are not reported, including the analysis population, missing-data procedures, handling of incomplete test sessions, and the exact AUC calculation. The registry does not clarify the “Baseline” timeframe label in relation to the described measurements during the test. It also does not report a multiplicity plan or an analysis plan.
The record describes a participant group with obesity and non-regular use of non-nutritive sweeteners, but gives limited information about participant characteristics and eligibility. The available description therefore does not support judging how representative the enrolled group was of other populations. In addition, results for incretin release and appetite-related substances are not reported, despite their appearance in the study rationale. These limits concern what can be concluded from the registry record; they do not establish what was or was not measured in the full study.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Sugar-replacement Sweeteners, and Blood Sugar Control — NCT01128829.
- Registry record last updated 2014-12-22; status last verified 2014-12.
- Results first posted 2014-12-22.
- 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.
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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 lists a completed, randomized, unmasked crossover study sponsored by Washington University School of Medicine. Enrollment is listed as 17, the condition is obesity, and the study phase is NA. The record gives a start date of 2010-05 and a primary completion date of 2012-02.
Participants received sucralose in water and water without sucralose in randomized sequence, each 10 minutes before a glucose load for a modified oral glucose tolerance test. The primary outcome was insulin concentration AUC during the test. The registry lists one outcome measure and one analysis.
The numerical primary result, its uncertainty, and the analysis method are not reported in the registry record. Safety entries list zero serious and zero other adverse events among 17 at risk in each category; the death entry is null. These data describe the registry record but do not establish the size or precision of the primary outcome contrast.