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 Effect of Exenatide, Sitagliptin or Glimepiride on Functional ß -Cell Mass (NCT00775684), a randomized na study. The primary outcome is Effect on Functional Beta-cell Mass as Determined by Change in ß-cell Secretory Capacity at 6 Months (μU/ml).
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00775684 |
| Phase | NA |
| Condition | Pre-diabetes, Type 2 Diabetes |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | None (open label) |
| Enrollment | 47 |
| Arms in the primary outcome | n/a |
| Lead sponsor | University of Pennsylvania |
| Results posted | Yes |
2. Clinical Question
Population
Adults with impaired fasting glucose or early type 2 diabetes were the intended population. The registry record lists pre-diabetes and type 2 diabetes as conditions. Its primary outcome description refers to 40 adult subjects with early type 2 diabetes, while the overall enrollment is listed as 47. The record does not explain the difference between these counts or state which participants contributed to each analysis.
Intervention
The trial compared three active drug regimens: exenatide, sitagliptin, and glimepiride. Exenatide was administered by subcutaneous injection twice daily, with an increase after 1 month if tolerated. Sitagliptin was taken by mouth every morning. Glimepiride was also taken by mouth every morning, with dose increases at monthly visits according to the regimen description.
Comparator
Each drug was compared within a randomized, parallel-group design. Glimepiride was described as an active comparator and insulin secretagogue; it was not a placebo or no-treatment group. The registry summary frames the comparison as whether exenatide or sitagliptin sustains or increases insulin production relative to glimepiride.
Primary question
The primary question concerned change from baseline to 6 months in beta-cell secretory capacity, estimated using the acute insulin response to arginine during a glucose clamp. The record identifies the measure as AIRmax and calls it functional beta-cell mass. It does not provide group-specific changes, a between-group estimate, a confidence interval, or a statistical test result, so the comparative result cannot be assessed from the registry record.
3. Trial Design
This was a randomized, controlled, parallel-group trial with no masking listed in the registry record. The interventions were exenatide, sitagliptin, and glimepiride, all active drug treatments. The record lists the phase as NA and the study status as completed. The University of Pennsylvania is named as sponsor. The study start is recorded as 2008-10, and primary completion as 2012-11.
The registry lists enrollment as 47. Separately, the description attached to the primary outcome says that the trial was conducted in 40 adult subjects with early type 2 diabetes. These figures describe different parts of the record, and no explanation of their relationship is reported in the registry record. They should not be combined or treated as a count of the participants included in the primary analysis. The numbers assigned to each treatment group for that analysis are not reported in the registry record.
The treatment descriptions specify exenatide (Byetta®), beginning at 5 µg injected subcutaneously twice daily and increasing after 1 month to 10 µg twice daily as tolerated by gastrointestinal effects. Sitagliptin (Januvia®) was listed at 100 mg by mouth every morning. Glimepiride (Amaryl®) was listed at 0.5 mg by mouth every morning, with increases of 0.5 - 1.0 mg at each monthly visit to achieve an average fasting glucose < 110mg/dl. These are regimen descriptions, not evidence about adherence or dose actually received by each participant.
The primary outcome timeframe is baseline and 6 months. Other listed outcomes include change in acute insulin response to arginine, insulin sensitivity at baseline and 6 months, and PG 50 at baseline and 6 months. The registry record does not report the allocation sequence method, concealment procedures, treatment adherence, participant flow, or detailed analysis populations.
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 | Exenatide | Sitagliptin | Glimepiride |
|---|---|---|---|
| STARTED | 17 | 13 | 17 |
| COMPLETED | 14 | 12 | 14 |
| NOT COMPLETED | 3 | 1 | 3 |
Analysis population for the primary outcome, as defined in the registry: We conducted a randomized controlled trial in 40 adult subjects with early Type 2 diabetes (T2D) who received the glucagon-like peptide (GLP-1) analog exenatide, the dipeptidyl peptidase IV inhibitor sitagliptin or the sulfonylurea glimepiride as an active comparator insulin secretagogue for 6 months.
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 | Exenatide | Sitagliptin | Glimepiride | Total |
|---|---|---|---|---|---|
| Participants analysed | 17 | 13 | 17 | 47 | |
| Age, Categorical: <=18 years | Participants | 0 | 0 | 0 | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 17 | 13 | 17 | 47 |
| Age, Categorical: >=65 years | Participants | 0 | 0 | 0 | 0 |
| Age, Continuous | years | 57 (SD 2) | 57 (SD 3) | 52 (SD 3) | 55.3 (SD 2.6) |
| Sex: Female, Male: Female | Participants | 6 | 4 | 7 | 17 |
| Sex: Female, Male: Male | Participants | 11 | 9 | 10 | 30 |
| Region of Enrollment: United States | participants | 17 | 13 | 17 | 47 |
6. Primary Endpoint
The registry lists the primary outcome as Effect on Functional Beta-cell Mass as Determined by Change in ß-cell Secretory Capacity at 6 Months (μU/ml), measured over Baseline and 6 months.
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | Standard Error |
| Unit | μU/ml |
| Endpoint classification | Continuous Endpoint |
The primary endpoint is described as change in beta-cell secretory capacity from baseline to 6 months, measured in μU/ml. The registry calls this capacity AIRmax and uses it as an estimate of functional beta-cell mass. The stated procedure uses the acute insulin response to arginine, or AIRarg, during a glucose clamp at 340mg/dl. In this setting, the response to arginine is used to estimate the maximum secretory response of beta cells under the clamp condition.
As general statistical and physiological context, a measure of secretory capacity addresses how much insulin the beta cells can release under a specified stimulus. It is not a direct count of beta cells. An estimated capacity measure can be useful when the research question concerns insulin secretion, but it should be interpreted as an operational measure defined by the test procedure rather than as a literal measurement of cell mass.
The registry describes comparing baseline-to-follow-up changes across treatment groups. That framing makes the between-group contrast central: a change within one group alone would not establish how that group compares with another. The record does not state the precise contrast, the method used to estimate it, or the group-level endpoint values. It also does not give a confidence interval or p-value for the primary endpoint. Therefore, the endpoint’s definition is available, but the magnitude and precision of the observed comparisons are not reported in the registry record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record identifies a biologically focused comparison among three active treatments and names a primary endpoint tied to insulin secretory capacity. It does not include the observed primary outcome values or the numerical comparison between treatments. As a result, the direction, size, and statistical uncertainty of the primary outcome cannot be described from the registry record. No claim about which group had a greater or smaller change is supported by the reported information.
The record also lists five outcome measures and five analyses, but does not provide the analysis results associated with those counts. The secondary outcomes named include change in AIRarg, insulin sensitivity at baseline and 6 months, and PG 50 at baseline and 6 months. Their definitions identify additional areas of measurement, but no numerical findings for them are reported in the registry record. The number of measures alone does not indicate whether results were consistent, contradictory, or inconclusive.
For a continuous outcome such as the stated primary measure, a comparison could be presented as a difference in average change between groups, with an uncertainty interval and a test result. General statistical context: an estimate describes the size and direction of a contrast, while a confidence interval indicates the range of values compatible with the data under the analysis assumptions. Neither can be interpreted when the estimate and interval are absent. A p-value alone, even if reported, would not describe the size or practical importance of an effect; in this record, no primary p-value is reported either.
The registry enrollment and the primary outcome description do not give the same participant count: enrollment is 47, while the outcome description refers to 40 adult subjects. The record does not explain whether these counts refer to different stages of recruitment, eligibility, follow-up, or analysis. It is therefore not possible to infer attrition, exclusions, or the sample size used for the endpoint. Group-specific analysis counts and missing outcome counts are also not reported in the registry record.
Safety entries list no serious adverse events, other adverse events, or deaths in the reported treatment groups. These entries describe recorded counts in the listed risk sets; they do not establish that no adverse events occurred outside the registry categories or reporting period. The record does not offer enough detail to evaluate the completeness of safety ascertainment.
Overall, the registry information supports a description of the trial question, treatment arms, endpoint, and some safety counts, but not an evaluation of comparative efficacy or precision. The absence of results in the registry record should not be read as evidence of no difference. It means that the relevant numerical findings are not reported there.
9. Statistical Methods Explained
Randomization assigns participants to treatment groups using a chance-based process. In general, this is intended to reduce systematic differences between groups at the outset, although the quality of randomization depends on how the sequence is generated and concealed. The registry identifies the study as randomized, but the sequence-generation method and allocation concealment are not reported in the registry record. The groups were parallel: each participant was assigned to a treatment group rather than moving through each treatment in sequence. Masking is listed as none, so the record describes the trial as unmasked.
What does the primary measure represent?
The primary outcome is a continuous measure of beta-cell secretory capacity, reported in μU/ml. The registry describes estimating AIRmax from the acute insulin response to arginine during a glucose clamp at 340mg/dl. It specifies change from baseline to 6 months and says changes were compared across groups. General statistical context: a continuous measure can vary over a range, and a group average can describe its central tendency. The registry lists mean as the parameter and standard error as the dispersion measure for this outcome. The actual group means, standard errors, and change estimates are not reported in the registry record.
A standard error describes the estimated precision of a sample mean, not the spread of individual participant measurements. A standard error can help quantify uncertainty about a mean, but it does not by itself describe how much participants differ from one another. General context: confidence intervals combine an estimate with its uncertainty to communicate a range of plausible values under the chosen statistical model. The registry record does not report a confidence interval for the primary comparison, or specify the model used to calculate one.
How should a between-group change be read?
When a study measures an outcome at baseline and follow-up, the change within each group describes how that group’s measured average shifted over time. The comparative question is whether those changes differ between groups. A within-group change is not the same as a between-group contrast, because changes can occur over time for reasons shared across groups. General statistical context: a randomized comparison is usually interpreted through the difference between treatment groups, with the estimate and uncertainty considered together. The registry states that changes were compared across groups, but does not report the numerical contrast or its method.
The trial has three treatment arms. A statistical analysis could make pairwise comparisons or use an overall group test followed by further comparisons, but which approach was used is not reported in the registry record. The record does not specify covariate adjustment, how baseline values were handled in the primary analysis, or whether the analysis followed the randomized assignment regardless of treatment received.
What do the planning assumptions mean?
The planning illustration is described as using a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. It is described as targeting a stated fraction of an observed effect. General statistical context: a sample-size calculation depends on assumptions about the effect to detect, variability, significance level, and desired power. Changing those assumptions changes the planned sample size. Such calculations are planning illustrations, not observed power and not evidence that a study had a particular probability of detecting an effect after its results are known. The registry information does not report the numerical planning outputs or the specific effect fractions used.
The described planning setup uses a two-arm comparison even though the trial lists three treatment groups. It should therefore not be mistaken for a complete description of all possible multi-arm comparisons. The registry record does not report a rationale for the chosen planning assumptions, the trial’s original sample-size justification, or whether planning assumptions were updated.
What can be inferred from absent results?
Nothing about the effect’s direction or magnitude can be recovered from an endpoint title or from the fact that an analysis was listed. General statistical context: a non-significant result, if one were reported, would not by itself show equivalence or absence of a meaningful difference. Equivalence or non-inferiority questions require a prespecified margin and an analysis suited to that question. Neither such margin nor such analysis is reported in the registry record. Here, the primary numerical results themselves are not reported, so even a distinction between statistically significant and statistically uncertain findings cannot be made.
There is no recalculated estimate in the registry information available for interpretation, and no sponsor-reported numerical result against which an independent recalculation could be compared. The registry record also does not describe an interim analysis, data-monitoring procedure, or detailed statistical analysis plan. These omissions do not establish what was or was not done outside the registry; they mean those methods are not reported in the registry record.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists five outcome measures and five analyses. It names the primary endpoint and identifies several secondary outcomes, including AIRarg, insulin sensitivity, and PG 50. The record does not specify how the analyses were mapped to outcomes or time points, nor does it describe any method for controlling the chance of false-positive findings across multiple comparisons. A prespecified hierarchy, adjustment procedure, or distinction between confirmatory and exploratory analyses is not reported in the registry record.
General statistical context: when many outcomes or comparisons are tested, the chance of at least one apparently unusual result can increase. Methods such as adjusted testing or a clearly defined primary outcome can help readers understand how multiple testing was handled. The primary outcome is identified in this record, but the statistical approach for the other outcomes and comparisons is not reported. Since numerical results are absent, it is not possible to assess whether results across outcomes were consistent or how any multiplicity approach affected interpretation.
Missing-data handling is not reported in the registry record. The record does not state how many participants had primary endpoint measurements at baseline or follow-up, how incomplete measurements were handled, or whether any imputation or sensitivity analysis was used. It also does not report reasons for missing observations or group-specific follow-up counts. The difference between enrollment of 47 and the 40 adult subjects mentioned in the primary outcome description is not explained; it cannot be treated as a missing-data count or as evidence of participant loss.
The analysis population is not described. The registry does not state whether the primary analysis included all randomized participants, only participants who completed treatment, or another defined group. It also does not report how treatment discontinuations, deviations, or changes in dose were handled. These uncertainties limit assessment of the analysis and do not establish that a particular approach was or was not used.
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 |
|---|---|---|---|
| Exenatide | 0 | 17 | 0.0% |
| Sitagliptin | 0 | 13 | 0.0% |
| Glimepiride | 0 | 17 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Exenatide | 0 of 17 |
| Sitagliptin | 0 of 13 |
| Glimepiride | 0 of 17 |
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 |
|---|---|
| Exenatide | 0 of 17 |
| Sitagliptin | 0 of 13 |
| Glimepiride | 0 of 17 |
The registry lists serious adverse events, other adverse events, and deaths for each treatment group. For exenatide, 17 participants were listed at risk for serious adverse events and 17 at risk for other adverse events; each recorded count was 0, and deaths were 0. For sitagliptin, 13 were listed at risk in each adverse-event category, with 0 recorded serious events, 0 other events, and 0 deaths. For glimepiride, 17 were listed at risk in each category, with 0 recorded serious events, 0 other events, and 0 deaths. No top serious-event terms are listed.
These are registry counts for the stated risk sets and categories. They should not be read as proof that a treatment has no safety risks, or as a complete account of all symptoms, events, or treatment burden. The record does not describe event definitions, the period of safety follow-up, how events were collected, or whether participants with incomplete follow-up were included in these counts. It also does not provide comparative statistical estimates for safety. A recorded count of 0 is a description of the entries, not a guarantee that the underlying risk is absent.
12. What the Result Does, and Does Not, Mean
The registry record establishes that investigators planned a randomized comparison of exenatide, sitagliptin, and glimepiride, with change in beta-cell secretory capacity at 6 months as the primary outcome. It also describes the test used to estimate that capacity and lists additional outcomes. These details clarify the research question and the measurements chosen to address it.
The record does not report the observed primary outcome results. There are no group-level changes, between-group estimates, confidence intervals, or p-values available in the registry record. It is therefore not possible to determine which treatment group had a larger change, how large any difference was, or how precisely it was estimated. The missing numerical results do not mean that the treatments were the same, and they do not mean that a difference was found.
Even if a numerical difference were available, an endpoint intended to estimate functional beta-cell mass would need to be interpreted as a measure defined by the physiological test, rather than as a direct count of cells. General statistical context: statistical evidence about an endpoint is not automatically evidence about every aspect of a disease or about longer-term outcomes. The listed primary timeframe is 6 months; the registry record does not report later primary endpoint follow-up.
The registry enrollment of 47 and the primary outcome description’s reference to 40 adult subjects are not reconciled. Without participant flow and analysis-population information, it is not possible to establish how many participants contributed to the endpoint or why the descriptions differ. The reported safety counts are also limited to the registry categories and risk sets and do not establish complete safety profiles.
Accordingly, the record supports a description of design and measurement, but not a conclusion about comparative treatment effects. A full interpretation would require the missing outcome estimates, uncertainty measures, analysis details, and participant accounting. No medical decision should be inferred from the registry record alone.
13. Why This Trial Matters Statistically
This trial illustrates how a registry can document a focused physiological question while leaving important statistical evidence unavailable. The primary outcome was not a broad clinical event but a continuous estimate of beta-cell secretory capacity. That choice makes the definition and measurement procedure especially important: readers need to know what was measured, how it was obtained, and how group differences were estimated.
The study’s three active treatment arms create a multi-group comparison. General statistical context: adding arms can make a study informative about several alternatives, but the analysis must clarify which contrasts answer the primary question and how multiple comparisons are treated. The registry identifies a primary endpoint and lists other outcomes, yet does not report its comparison strategy or multiplicity approach. These omissions make it harder to distinguish confirmatory analyses from other analyses.
The record also shows why participant counts must be read in context. Overall enrollment is listed as 47, while the primary outcome description refers to 40 adult subjects. Without a flow account or defined analysis populations, those figures do not reveal how many observations were available for each comparison. This is relevant to both precision and the assessment of missing data, but the record does not permit a numerical evaluation of either.
Finally, statistical interpretation depends on estimates and uncertainty, not just a stated research hypothesis or a defined endpoint. The primary numerical results are not reported in the registry record. That absence prevents an assessment of effect size, precision, or consistency across outcomes. It is a useful reminder that a completed randomized design and a detailed endpoint description are not substitutes for transparent reporting of the results and analysis.
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 trial-specific limitations in the registry information constrain interpretation. Most importantly, the primary outcome results are not reported: there are no group-specific measurements, changes, between-group contrasts, confidence intervals, or test results. The record therefore cannot support a quantitative account of the primary comparison or its uncertainty.
The participant counts are not fully reconciled. Enrollment is listed as 47, while the primary outcome description refers to 40 adult subjects. No participant-flow information explains the difference, and the record does not identify the number randomized to each arm or the number included in each outcome analysis. These counts do not establish attrition or missingness on their own.
The registry also does not report the randomization sequence method, allocation concealment, or detailed analysis plan. Masking is listed as none. The record does not specify the primary statistical model, treatment of baseline values, analysis population, missing-data procedure, or handling of protocol deviations. It does not describe adjustment for multiple outcomes or comparisons, interim analyses, or monitoring procedures. Their absence from the record should not be taken as evidence that they were not addressed outside it.
The safety record includes 0 events in the listed categories and risk sets, but does not report event definitions, ascertainment methods, or detailed duration of safety follow-up. The listed adverse-event entries therefore cannot provide a comprehensive safety assessment. Finally, the primary endpoint is a test-based estimate of functional beta-cell mass, and the registry provides no numerical results with which to assess its behavior in this trial.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Effect of Exenatide, Sitagliptin or Glimepiride on Functional ß -Cell Mass — NCT00775684.
- Registry record last updated 2022-06-07; status last verified 2022-05.
- Results first posted 2017-12-06.
- 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
The registry describes a completed, randomized, unmasked, parallel-group trial sponsored by the University of Pennsylvania. It compared exenatide, sitagliptin, and glimepiride in people with impaired fasting glucose or early type 2 diabetes. Enrollment is listed as 47; the primary outcome description separately refers to 40 adult subjects with early type 2 diabetes, and the difference is not explained.
The primary outcome was change in beta-cell secretory capacity from baseline to 6 months, estimated using AIRmax from the acute insulin response to arginine during a glucose clamp. Additional outcomes included AIRarg, insulin sensitivity, and PG 50. The registry lists 0 serious adverse events, 0 other adverse events, and 0 deaths in each treatment group’s stated risk set. Numerical primary outcome results and detailed analysis methods are not reported in the registry record, so comparative effects and their precision cannot be assessed.