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 Evaluation of Continuous Glucose Monitoring in Participants With Type 2 Diabetes Mellitus (MK-0000-258 AM2) (NCT01537120), a na phase 1 study. The primary outcome is 24 Hour Weighted Mean Glucose (WMG) At 2 Weeks.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT01537120 |
| Phase | Phase 1 |
| Condition | Type 2 Diabetes Mellitus |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | Single |
| Enrollment | 25 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Merck Sharp & Dohme LLC |
| Results posted | Yes |
2. Clinical Question
The clinical question was whether 24-hour weighted-mean glucose (WMG), measured using continuous glucose monitoring, differed after placebo treatment and after vildagliptin treatment in participants with type 2 diabetes mellitus. The registry summary states a primary hypothesis that two weeks of vildagliptin 50 mg taken orally twice daily would lead to a statistically significant decrease in WMG relative to placebo. That is the stated hypothesis, not a reported finding: numerical WMG results and a statistical comparison are not reported in the registry record.
Population
Participants with type 2 diabetes mellitus. The registry lists enrollment of 25. The primary outcome population is described as per-protocol: participants who complied with assigned medication during each study period.
Intervention
Vildagliptin 50 mg tablets taken orally twice daily. The outcome description specifies measurement after two weeks of vildagliptin treatment.
Comparator
Placebo tablets taken orally twice daily. The arm description gives a sequence of placebo for 3 weeks followed by vildagliptin for 12 weeks; the primary outcome description refers to measurements after two weeks of each treatment.
Primary question
Was 24-hour WMG lower after vildagliptin than after placebo? The registry states this as a hypothesis, but does not report the results needed to answer it.
The study is not described as a randomized comparison. Because the same sequence is described as placebo followed by vildagliptin, the observed periods cannot be interpreted as randomized, like-for-like treatment groups. The registry record also does not report a numerical estimate of the within-participant change or its uncertainty.
3. Trial Design
This is a Phase 1, single-group study with single masking and allocation recorded as not applicable. The registry lists enrollment of 25 and status as completed. The start is recorded as 2011-12 and primary completion as 2012-10. These administrative details describe the registered study, but they do not establish how many participants contributed usable data to each outcome.
The arm description gives a sequential schedule: participants received placebo tablets orally twice a day for 3 weeks, then received vildagliptin 50 mg orally twice daily over the next 12 weeks. The primary outcome description states that WMG was measured after 2 weeks of placebo treatment and again after 2 weeks of vildagliptin treatment. The brief summary instead frames the primary hypothesis around two weeks of vildagliptin compared with placebo. The registry record does not explain the difference between the treatment durations stated in the arm description and the outcome description.
A single-group sequence is different from a randomized parallel-group trial. In a randomized trial, treatment assignment is designed to make groups comparable on average. Here, the registered sequence places placebo before vildagliptin, so treatment and period are linked. Changes between measurements could reflect treatment, time, measurement conditions, or other period-related influences; the record does not report a design feature that separates these possibilities.
Single masking is recorded, but who was masked is not reported in the registry record. The method used to generate or conceal allocation is not reported, and the registered allocation is not applicable. These features limit what can be inferred about protection from expectation or selection effects. A sample-size justification, planned interim analyses, and a fuller statistical analysis plan 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.
Before assignment: After enrollment, participants previously treated with both metformin and sulfonylurea, discontinued sulfonylurea usage and underwent washout of sulfonylurea over a period of 8 weeks prior to treatment. Non-washout participants were enrolled on a clinical regimen of metformin alone.
Enrolled
| Stage | Placebo → Vildagliptin |
|---|---|
| STARTED | 25 |
| COMPLETED | 25 |
| NOT COMPLETED | 0 |
8 Weeks Washout
| Stage | Placebo → Vildagliptin |
|---|---|
| STARTED | 25 |
| COMPLETED | 24 |
| NOT COMPLETED | 1 |
Reasons for not completing this period:
| Reason | Placebo → Vildagliptin |
|---|---|
| Inclusion/exclusion criteria not met | 1 |
3 Weeks Placebo
| Stage | Placebo → Vildagliptin |
|---|---|
| STARTED | 24 |
| COMPLETED | 23 |
| NOT COMPLETED | 1 |
Reasons for not completing this period:
| Reason | Placebo → Vildagliptin |
|---|---|
| Withdrawal by Subject | 1 |
12 Weeks Vildagliptin
| Stage | Placebo → Vildagliptin |
|---|---|
| STARTED | 23 |
| COMPLETED | 23 |
| NOT COMPLETED | 0 |
Analysis population for the primary outcome, as defined in the registry: Per-Protocol Population: all participants who complied with the assigned medication during each period of 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.
| Characteristic | Unit | Placebo → Vildagliptin |
|---|---|---|
| Participants analysed | 25 | |
| Age, Continuous | Years | 62 (SD 5.6) |
| Sex: Female, Male: Female | Participants | 1 |
| Sex: Female, Male: Male | Participants | 24 |
6. Primary Endpoint
The registry lists the primary outcome as 24 Hour Weighted Mean Glucose (WMG) At 2 Weeks, measured over At 2 weeks after Placebo treatment and again at 2 weeks after Vildagliptin treatment.
| Element | Registry entry |
|---|---|
| Result type | Geometric Mean |
| Measure of spread | Geometric Coefficient of Variation |
| Unit | mg/dL |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint is 24-hour weighted-mean glucose, measured at 2 weeks after placebo treatment and again at 2 weeks after vildagliptin treatment. Participants wore two continuous glucose monitors during a 24-hour measurement period. The devices produced average glucose values approximately every 5 minutes. The registry says glucose concentration was calculated from the area under the curve over 0-24 hours and expressed as 24-hour WMG.
WMG provides a summary of glucose exposure across the measurement period. In general, a time-weighted average can describe the overall level across an interval rather than relying on a single measurement. Continuous monitoring can capture changes throughout that interval, though the result remains a summary and does not by itself describe every glucose fluctuation or its timing.
The outcome is reported as a geometric mean, with geometric coefficient of variation as the dispersion measure. In general, geometric summaries are useful for measurements that are analysed on a multiplicative scale or whose distribution is skewed. The geometric coefficient of variation describes relative spread on that scale. The registry record does not report the numerical group or period summaries, the coefficient of variation values, or a treatment contrast, so the magnitude and precision of any observed difference cannot be assessed from the record.
The primary outcome population is per-protocol, defined in the record as participants who complied with assigned medication during each period. That definition indicates that the result is intended to concern those meeting the treatment-compliance condition, rather than necessarily everyone enrolled. The number included in this primary analysis is not reported in the registry record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry states a hypothesis that vildagliptin would decrease 24-hour WMG relative to placebo. It does not report the WMG values, an estimated contrast, a confidence interval, a p-value, or a conclusion about whether the hypothesis was supported. Consequently, the direction, size, and statistical precision of the primary outcome cannot be determined from the registry record. The planned hypothesis must not be mistaken for an observed result.
The design also matters for interpretation. The registered study is single-group, with placebo followed by vildagliptin, rather than a randomized comparison. A before-and-after contrast within a sequence can be informative about measurements made during the two periods, but it does not isolate treatment from period effects as a randomized, concurrent comparison is designed to do. For example, general statistical reasoning recognizes that changes over time, differences in measurement circumstances, or carryover from an earlier period can contribute to a within-sequence contrast. Whether any such influences occurred in this trial is not reported in the registry record.
The record describes the primary outcome as per-protocol. In general, analyses restricted to participants meeting treatment-compliance criteria can differ from analyses that retain everyone according to original assignment. Such results describe the analysed population and may be affected by who does or does not meet the compliance definition. The record does not report the number in the per-protocol analysis, the reasons for exclusion, or a complementary analysis population.
Safety counts are reported separately: serious adverse events are listed as zero in both treatment groups, while other adverse events are listed as 8 for vildagliptin and 6 for placebo. The corresponding at-risk counts are 23 and 24. These are registry counts, not an efficacy comparison, and the record does not provide event descriptions for the other adverse events. Deaths are not reported in the registry record. The absence of serious adverse events in these entries should be read as a description of the recorded counts, not as proof that an event is impossible or that a treatment is safe in broader use.
Overall, the record documents the study question, sequence, measurement method, and some safety counts, but it does not provide the primary numerical results needed to judge the observed glucose outcome. No claim that vildagliptin did or did not change WMG is supported by the registry information recorded.
9. Statistical Methods Explained
The primary outcome is a continuous measurement summarized as a geometric mean. In general, a mean compresses multiple observations into a single summary, while a measure of dispersion conveys how much observations vary around that summary. Here the registry identifies the geometric coefficient of variation as the dispersion measure. That choice describes relative variation in relation to the geometric scale; it is not the same quantity as a standard deviation on the original measurement scale. The record does not give the numerical summaries or enough detail to reconstruct an analysis.
What does continuous glucose monitoring contribute?
In general, continuous monitoring collects repeated measurements over time, allowing a summary to represent an interval rather than a single time point. The registry describes two monitors worn over a 24-hour period, with average glucose values approximately every 5 minutes. It then describes using the area under the curve from 0-24 hours to calculate WMG. Area under the curve aggregates measurements over time; expressing it as a weighted mean makes the result interpretable as an average glucose level over the monitored interval. The record does not report device handling, calibration procedures, or how gaps in monitoring were treated.
Why use a geometric summary?
General statistical explanation: geometric summaries operate on a multiplicative scale and can be appropriate when measurements are positive and their variability is better described proportionally than by fixed additive distances. A geometric coefficient of variation provides a relative measure of spread. This does not establish why the investigators selected these statistics; the rationale for that choice is not reported in the registry record. Without the observed values and analysis details, it is not possible to assess whether the distribution or scale supported the chosen summaries.
What would a treatment contrast mean?
In general, a contrast compares outcomes under different conditions. For a sequential study, a contrast between the placebo period and the vildagliptin period could be expressed as a within-participant change, provided the same participants contribute under both conditions and the analysis accounts for the paired structure. A paired analysis uses the relationship between repeated measurements on the same participant. Treating the measurements as independent would ignore that relationship. The registry record does not report the estimator, model, or test used for the primary outcome, so it is not possible to say how this dependence was handled.
The sequence is placebo first and vildagliptin later in the arm description. General statistical reasoning highlights that, without randomized order or a concurrent randomized control, treatment and period may be entangled. A difference in measurements can include treatment-related change and time-related change. Other possible concerns in a repeated-period design include carryover and changes in adherence or measurement conditions. These are general considerations, not findings about what happened in this study; the registry record does not report analyses of these effects.
How should statistical significance and uncertainty be read?
In general, a p-value measures how unusual data at least as extreme as those observed would be under a specified null model and its assumptions. It does not measure the probability that the null hypothesis is true, nor does it by itself show the size or practical importance of an effect. A confidence interval gives a range of estimates compatible with the data and analysis at a stated confidence level. A narrow interval indicates greater precision than a wide interval, but precision does not remove bias from study design or measurement.
The brief summary says the primary hypothesis was a statistically significant decrease in WMG relative to placebo. However, the registry record does not report a p-value, confidence interval, or estimate. Statistical significance therefore cannot be evaluated, and no claim about the size or precision of a change can be made. Even if a test result were available, it would need to be interpreted alongside the design and analysis population.
Why can over-dispersion matter?
General statistical explanation: over-dispersion occurs when observed variability is greater than a model assumes. If a model understates variability, standard errors may be too small and inferential results can appear more precise than warranted. A suitable model may need to represent the observed dispersion. This trial’s registry record identifies a geometric coefficient of variation for the primary outcome but does not report a model, dispersion diagnostics, or a statement about over-dispersion. It would therefore be inappropriate to claim that over-dispersion was present or that a particular adjustment was used.
The record lists three outcome measures and three analyses, but does not report the statistical procedures or whether multiplicity was addressed. In general, testing several outcomes or contrasts can increase the chance of at least one apparently unusual result if each is interpreted without accounting for the set of tests. Adjustment procedures and pre-specified outcome hierarchies are possible approaches, but their use in this trial is not reported. Likewise, interim analyses and stopping rules are not reported in the registry record.
A planning illustration is described as using the observed effect, a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation, with effects considered as stated fractions of the observed effect. It is explicitly a planning illustration rather than the trial’s own design. Such calculations are not observed power and cannot establish that the original study had adequate power. The trial’s sample-size justification is not reported, and the numerical primary effect needed to assess the illustration is not reported in the registry record.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists three outcome measures and three analyses. The named secondary outcomes are Hemoglobin A1C (HbA1C) at 2 weeks and HbA1C at 12 weeks, alongside the primary 24-hour WMG outcome. The record does not state whether all analyses correspond one-to-one with those measures, whether additional contrasts were tested, or which outcomes were designated for formal hypothesis testing beyond the stated primary hypothesis.
Multiplicity concerns arise in general when several outcomes, time points, or statistical comparisons are examined. If each test is treated as a separate opportunity to declare a result, the chance of at least one false-positive finding can increase. Common approaches include adjusting significance thresholds or specifying a hierarchy of tests, but the use of any such method is not reported in the registry record. The record also does not report the analysis plan in enough detail to assess whether analyses were selected before results were known.
Missing-data handling is not reported in the registry record. The outcome description identifies a per-protocol population as participants who complied with assigned medication during each period, but does not state how missing monitor data, incomplete periods, or participants who did not meet the compliance definition were handled. The number included in the primary analysis and reasons for missingness or exclusion are not reported.
An intention-to-treat analysis, imputation approach, sensitivity analysis, or missingness assumption is not reported in the registry record. In general, missingness can affect results when the availability of measurements is related to participant characteristics or outcomes. Without details on completeness and handling, the robustness of the primary outcome analysis cannot be assessed. Interim analyses and any adjustments related to them are also not reported.
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 |
|---|---|---|---|
| Vildagliptin 50 mg | 0 | 23 | 0.0% |
| Placebo | 0 | 24 | 0.0% |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 5% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Vildagliptin 50 mg | 8 of 23 |
| Placebo | 6 of 24 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Vildagliptin 50 mg | Placebo |
|---|---|---|---|
| Reaction site cannula | General disorders | 3 of 23 | 5 of 24 |
| Upper respiratory tract infection | Infections and infestations | 4 of 23 | 4 of 24 |
| Headache | Nervous system disorders | 4 of 23 | 4 of 24 |
| Reaction CGM Site | General disorders | 2 of 23 | 2 of 24 |
| Dizziness | Nervous system disorders | 2 of 23 | 2 of 24 |
| Tiredness | General disorders | 3 of 23 | 0 of 24 |
| Nausea | Gastrointestinal disorders | 2 of 23 | 0 of 24 |
| Vomiting | Gastrointestinal disorders | 2 of 23 | 0 of 24 |
The serious adverse event entries list 0 affected participants in the vildagliptin group, with 23 at risk, and 0 in the placebo group, with 24 at risk. The registry lists 8 participants with other adverse events among 23 at risk for vildagliptin, and 6 among 24 at risk for placebo. These are the counts as recorded; no additional percentage or comparative risk calculation is needed to describe them.
The registry’s categories distinguish serious adverse events from other adverse events. The terms or event descriptions for the other adverse events are not reported in the registry record. The list of top serious event terms is empty, consistent with the recorded absence of serious events in these entries, but it does not provide detail about non-serious events. Deaths are not reported in the registry record.
These figures should not be read as a randomized safety comparison. The study is recorded as single-group, and the registered treatment sequence is placebo followed by vildagliptin. The at-risk counts refer to the listed groups and should not be added to infer a count of distinct participants. The registry does not report event timing, duration, severity for other events, attribution, or the approach used to collect and classify events. The counts describe what is entered in the record; they do not establish the likelihood of events in other populations or settings.
12. What the Result Does, and Does Not, Mean
The record establishes that the study evaluated continuous glucose monitoring as a way to measure glucose outcomes around placebo and vildagliptin treatment. It specifies 24-hour WMG as the primary endpoint and gives a measurement description involving two monitors and an area-under-the-curve calculation. It also records a hypothesis of lower WMG after vildagliptin than after placebo.
What the record does not establish is whether WMG decreased, by how much it may have changed, or how uncertain any estimate was. Numerical results, a treatment contrast, a p-value, and a confidence interval are not reported in the registry record. The hypothesis cannot stand in for those results. The two HbA1C outcomes are named, but their results are also not reported in the registry record.
The design limits causal interpretation. The study is single-group, and the treatment order is placebo followed by vildagliptin in the arm description. There is no registered randomized, concurrent comparison. General statistical reasoning therefore cautions that a difference between periods could be associated with treatment, but could also reflect period-related changes or other factors. The record does not report methods that would separate these sources of change.
The safety entries document no serious adverse events in either listed group and record other adverse events in both. They do not give the event terms for the other adverse events, and deaths are not reported in the registry record. Those entries describe the available safety record, not a complete characterization of risks across other populations or longer periods.
Accordingly, the registry supports a description of the question, study sequence, endpoint method, and recorded adverse-event counts. It does not support a conclusion that vildagliptin did or did not change glucose, or that it is effective or ineffective. The missing outcome estimates and the nonrandomized sequence are central to interpreting what this study can say.
13. Why This Trial Matters Statistically
Statistically, the study is notable for using a repeated glucose measurement to assess a treatment-period question. Continuous monitoring can summarize glucose across a 24-hour interval rather than relying on one isolated measurement. The registry’s use of a weighted mean derived from the area under the curve illustrates how measurements collected over time can be condensed into an endpoint for analysis.
The design also highlights a distinction between repeated measurement and randomized comparison. Measuring the same participants in sequence can make within-participant comparisons possible, but treatment order matters. With placebo preceding vildagliptin, treatment condition and period are linked. This makes it important to distinguish a measured change across periods from a causal treatment effect. The registry record does not report a design or analysis that resolves this issue.
The chosen summary statistics raise useful interpretation questions. A geometric mean and geometric coefficient of variation describe outcomes on a multiplicative scale and emphasize relative rather than purely additive variation. Readers need both a central estimate and an appropriate measure of uncertainty to judge the result. Those numerical results are not reported in the registry record, so the statistical meaning of the primary outcome cannot be evaluated beyond its definition.
The record also illustrates why registration details and outcome results serve different purposes. The planned hypothesis, treatment schedule, and analysis population describe what was intended or specified; they do not show what the analysis found. The missing efficacy estimates, analysis details, and missing-data information prevent assessment of precision and robustness. These are important limits even though the record identifies the outcome and measurement approach clearly.
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 main trial-specific limitation is the single-group, sequential design. The arm description places placebo before vildagliptin, and allocation is recorded as not applicable. Without a randomized concurrent comparator, treatment-period differences may be entangled with changes over time or other period effects. The registry record does not report a method to distinguish these explanations.
The descriptions of duration are not fully aligned. The arm description says placebo was taken for 3 weeks before vildagliptin was taken over the next 12 weeks. The primary outcome description refers to measurements after 2 weeks of placebo and again after 2 weeks of vildagliptin, while the brief summary frames the hypothesis around two weeks of vildagliptin relative to placebo. The record does not explain how these descriptions relate to the full treatment schedule.
Primary outcome results are not reported in the registry record. The estimate, geometric summaries, dispersion values, confidence interval, p-value, and primary analysis method are unavailable, as are results for the named HbA1C outcomes. The number contributing to the per-protocol outcome analysis is also not reported. This prevents assessment of effect size, precision, missingness, and the relationship between planned and analysed populations.
Additional details are absent: the masking target, sample-size justification, interim analyses, multiplicity approach, missing-data methods, and model diagnostics are not reported. Safety reporting is limited to counts; event terms for other adverse events and deaths are not reported in the registry record. The registry title refers to an oral insulin secretagogue, while the brief summary describes vildagliptin as a DPP4 inhibitor; the record does not explain this difference in characterization.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Evaluation of Continuous Glucose Monitoring in Participants With Type 2 Diabetes Mellitus (MK-0000-258 AM2) — NCT01537120.
- Registry record last updated 2015-08-19; status last verified 2015-08.
- Results first posted 2013-12-03.
- 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 record identifies a completed Phase 1, single-group study of continuous glucose monitoring in participants with type 2 diabetes mellitus. It lists enrollment of 25 and describes placebo followed by vildagliptin 50 mg taken orally twice daily. The primary endpoint is 24-hour WMG at 2 weeks after each treatment period, summarized as a geometric mean with geometric coefficient of variation.
The stated hypothesis is that WMG would decrease after vildagliptin relative to placebo. Numerical results and inferential statistics for that outcome are not reported in the registry record. The study’s sequential, nonrandomized structure limits a direct causal interpretation of differences between periods. The record lists serious adverse event counts of 0 in each group and other adverse event counts of 8 for vildagliptin and 6 for placebo. Event descriptions for the other adverse events and deaths are not reported.