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 A Study to Test MK-0941 in Adults With Type 2 Diabetes Mellitus With Inadequate Glycemic Control on Insulin (MK-0941-018) (NCT00824616), a randomized phase 2 study. The primary outcome is Change From Baseline in Hemoglobin A1c (HbA1c) Level.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00824616 |
| Phase | Phase 2 |
| Condition | Type 2 Diabetes Mellitus |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Double |
| Enrollment | 68 |
| Arms in the primary outcome | 2 |
| Lead sponsor | Merck Sharp & Dohme LLC |
| Results posted | Yes |
2. Clinical Question
Population
Adults with type 2 diabetes mellitus and inadequate glycemic control while taking insulin. The primary analysis population was the Full Analysis Set: randomized participants who took at least one dose of MK-0941 or placebo and had a baseline or post-randomization measurement.
Intervention
MK-0941 tablets three times daily, given as add-on therapy to an insulin injection once daily.
Comparator
Placebo tablets three times daily, with an insulin injection once daily.
Primary question
How did HbA1c change from baseline to the end of treatment at Week 20 in the MK-0941 group compared with the placebo group?
The trial asks whether the average change in HbA1c differed between participants assigned to MK-0941 and those assigned to placebo while both groups continued insulin. The endpoint is a continuous measure, and a negative change indicates a reduction in HbA1c. The registry record reports least-squares mean changes for each group and a net mean difference from a longitudinal data analysis model.
The posted group estimates were -0.26 for MK-0941 and -0.15 for placebo. The reported net mean difference was -0.11, with a 95% confidence interval from -0.81 to 0.58 and p = 0.745. These estimates describe the trial results; they do not by themselves establish whether a difference would be clinically important. The registry record does not report a threshold for clinical importance.
3. Trial Design
This was a Phase IIa, multicenter, randomized, double-blind, placebo-controlled, parallel-group trial. The registry record lists 68 participants enrolled. The primary outcome results are reported for 34 participants in each group. Participants assigned to MK-0941 received tablets three times daily alongside an insulin injection once daily. Participants assigned to placebo received placebo tablets on the same schedule alongside an insulin injection once daily.
The study began in 2009-01, reached primary completion in 2010-05, and is listed as completed. The primary endpoint compared change in HbA1c from baseline on Day 1 to end of treatment at Week 20. HbA1c is a continuous outcome, so the registry reports least-squares means and a model-based comparison rather than a count of participants who crossed a threshold.
Random allocation is intended to create groups that are comparable on average, while double masking is intended to reduce the influence of expectations on care and outcome assessment. A placebo comparison helps distinguish changes observed with the study drug from changes that may occur with background insulin, study participation, or other influences. These are general purposes of such design features; the registry record does not describe the allocation procedure, masking procedures, or any checks of masking.
The record identifies a Full Analysis Set for the primary outcome. It included randomized participants who took at least one dose of study drug and had a baseline or post-randomization measurement. Details about the number excluded from that population, if any, and the reasons are not reported in the registry record. The protocol’s sample-size justification, planned interim analyses, and further 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.
Overall Study
| Stage | Placebo | MK-0941 |
|---|---|---|
| STARTED | 34 | 34 |
| COMPLETED | 28 | 27 |
| NOT COMPLETED | 6 | 7 |
Reasons for not completing this period:
| Reason | Placebo | MK-0941 |
|---|---|---|
| Adverse Event | 2 | 1 |
| Creatinine/Creatinine Clearance | 0 | 2 |
| Hyperglycemia | 1 | 1 |
| Lack of Efficacy | 2 | 1 |
| Lost to Follow-up | 0 | 1 |
| Withdrawal by Subject | 1 | 1 |
Analysis population for the primary outcome, as defined in the registry: Full Analysis Set Population, which consisted of all randomized participants who took at least one dose of study drug (MK-0941 or Placebo) and had a baseline or post-randomization measurement.
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 | MK-0941 | Total |
|---|---|---|---|---|
| Participants analysed | 34 | 34 | 68 | |
| Age, Continuous | years | 55.5 (SD 8.8) | 54.1 (SD 10.2) | 54.8 (SD 9.5) |
| Sex: Female, Male: Female | Participants | 15 | 16 | 31 |
| Sex: Female, Male: Male | Participants | 19 | 18 | 37 |
6. Primary Endpoint
The registry lists the primary outcome as Change From Baseline in Hemoglobin A1c (HbA1c) Level, measured over Baseline (Day 1) and End of Treatment (Week 20).
| Element | Registry entry |
|---|---|
| Result type | Least Squares Mean |
| Measure of spread | 95% Confidence Interval |
| Unit | % HbA1c |
| Endpoint classification | Continuous Endpoint |
The primary endpoint was change from baseline in hemoglobin A1c (HbA1c), expressed as % HbA1c, assessed from baseline on Day 1 to the end of treatment at Week 20. HbA1c is the percentage of hemoglobin that has glucose attached to it. As described in the registry record, HbA1c is related to average blood glucose concentration over the previous 2-3 months. A higher HbA1c indicates a higher average plasma glucose concentration, while a negative change from baseline indicates a reduction in HbA1c.
HbA1c is used as a continuous measure of glycemic control. In general, continuous outcomes retain information about the size and direction of change, rather than reducing results to whether a participant did or did not meet a selected cutoff. The reported least-squares means represent model-based average changes, and the confidence intervals convey uncertainty around those estimates.
The endpoint captures change over the study’s specified assessment period, not every fluctuation in glucose during that period. The registry record does not report a threshold defining a clinically important HbA1c difference, nor does it provide a secondary HbA1c endpoint. Interpretation should therefore focus on the reported estimates, their uncertainty, and the stated analysis population rather than assuming an unreported clinical threshold.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The least-squares mean change in HbA1c was -0.26 in the MK-0941 group and -0.15 in the placebo group. Negative values indicate reductions from baseline according to the endpoint description. The reported net mean difference was -0.11. Its 95% confidence interval ranged from -0.81 to 0.58, and the reported p-value was 0.745.
The confidence interval includes zero. In general, a confidence interval describes a range of values compatible with the data and the statistical model at the stated confidence level. Here, its span includes both negative and positive values, so the estimate is imprecise about the direction and size of the between-group difference. The interval also extends well beyond the point estimate on either side. The registry record does not report a clinical-importance threshold, so the interval cannot be classified against such a threshold.
The p-value is the result of the reported statistical test under its assumptions. A p-value of 0.745 is not evidence that the groups are identical, and it is not the probability that the null hypothesis is true. It indicates that the posted analysis did not produce a small p-value against the tested null. The result should be read alongside the effect estimate and confidence interval, which show the range of differences that remain compatible with the analysis.
The group-level estimates are close in magnitude, but the uncertainty around the comparison matters. A point estimate alone does not show how precisely the trial estimated the difference. The confidence interval indicates that the data do not pin down a narrow range of possible between-group effects. The trial’s enrollment was 68, with 34 participants in each group for the primary outcome, and that size limits how much precision can be expected from a single study, especially when the observed comparison is uncertain.
These are statistical observations about the posted results, not a conclusion that MK-0941 does or does not work. The registry record provides a Week 20 outcome and does not report a longer-term HbA1c comparison. It also does not report a predefined threshold for clinical importance. The results therefore address the measured mean change over the stated endpoint period and should not be extended to other outcomes, longer follow-up, or other populations.
Safety information is reported separately. The counts of participants with serious adverse events were 1 in each group, and other adverse events were reported for 13 participants receiving placebo and 11 receiving MK-0941. These descriptive counts do not resolve the uncertainty in the primary endpoint and should not be treated as a statistical test of safety differences. The number of participants and the available reporting do not support broad conclusions about uncommon events.
9. Statistical Methods Explained
The primary endpoint is continuous: it records the amount of change in HbA1c rather than classifying participants into outcome categories. The registry reports the least-squares mean change for each group and names a Longitudinal Data Analysis (LDA) model for the between-group comparison. The reported result is a mean difference (net) with a 95% confidence interval and p-value.
What does a least-squares mean represent?
In general, a least-squares mean is an estimated group mean from a statistical model. It can differ from a simple arithmetic average because it is derived within the model’s framework and may account for specified features of the data. The registry record reports least-squares mean changes of -0.15 for placebo and -0.26 for MK-0941. It does not provide enough detail to identify all model terms, covariates, or assumptions behind those estimates.
What is a longitudinal analysis?
In general, longitudinal methods are designed for measurements collected over time. They can use repeated observations to estimate change and compare patterns between groups while accounting for the relationship among measurements from the same participant. The registry names an LDA model, but it does not report the model specification, covariance structure, handling of incomplete measurements, or whether other covariates were included. Those details should not be inferred from the model name alone.
The registry states that the primary outcome timeframe ran from baseline on Day 1 to end of treatment at Week 20. The posted result is an endpoint change comparison. The record does not provide a sequence of intermediate group estimates or a detailed account of how measurements at intermediate visits contributed to the fitted model. Consequently, the model’s precise use of all available longitudinal observations is not reported in the registry record.
How should the confidence interval be read?
In general, a confidence interval describes uncertainty around an estimate under the statistical model and its assumptions. The reported 95% confidence interval for the net mean difference extends from -0.81 to 0.58. Since it includes zero, the data are compatible with no difference as well as with differences in either direction. A confidence interval is not a guarantee that the true value lies in its bounds, and it does not identify which values would be clinically important. No clinical-importance threshold is reported for this endpoint.
What does the p-value add?
The reported p-value is 0.745. In general, a p-value describes how unusual data at least as incompatible with a specified null hypothesis would be if that null hypothesis and the test assumptions were correct. It is not the probability that the null hypothesis is true. It also does not measure the size or clinical relevance of a difference. In this trial, the p-value should be interpreted together with the net mean difference and its confidence interval, not in isolation.
Why can the model result differ from a simple calculation?
In general, an unadjusted calculation from group summaries may not match a model-based comparison. The model may use participant-level repeated measurements and specified analysis assumptions, whereas group-level summaries condense the data. The record’s posted group values are least-squares means, and the reported contrast is from an LDA model. A simple contrast reconstructed from summary values would not necessarily reproduce that model result.
The record does not contain a separate simple recalculated two-arm contrast for this continuous endpoint. The displayed model-based net difference, confidence interval, and p-value are therefore the inferential results to use when describing the registry’s own analysis. The lack of a separate recalculation does not mean that the model result is free of assumptions; it means that a distinct unadjusted comparison is not available in the posted record.
What does over-dispersion mean in general?
Over-dispersion is a concern for some count-based models when observed variability exceeds what the assumed model allows. The primary HbA1c endpoint is continuous and is analyzed using a longitudinal data analysis model, so a count-model over-dispersion explanation is not applicable to this posted primary comparison. In general, analysts choose a model appropriate to the outcome type and its distribution; the record does not describe additional diagnostic checks for the LDA model.
The registry identifies a Full Analysis Set consisting of randomized participants who took at least one dose of study drug and had a baseline or post-randomization measurement. In general, defining an analysis population makes clear which participants contribute to an estimate. The record does not report the number of randomized participants who did not meet this definition, how missing Week 20 measurements were handled, or sensitivity analyses for missing data. These omissions limit assessment of how robust the estimate is to incomplete outcome measurement.
For planning, the registry’s stated illustration assumptions use a two-sided significance level of 0.05, equal allocation, a normal approximation, and effects defined as fractions of the observed effect. Such calculations are planning illustrations based on an observed effect, not observed power and not evidence about the trial’s original design rationale. The protocol’s sample-size justification is not reported in the registry record. No planning count should be interpreted as an observed trial result.
10. Analyses Reported by the Sponsor
| Method | Estimate | 95% CI | P-value |
|---|---|---|---|
| Longitudinal Data Analysis (LDA) model | Mean Difference (Net) -0.11 | -0.81 to 0.58 | 0.745 |
The registry’s reported comparison is a Longitudinal Data Analysis model result: a net mean difference of -0.11, a 95% confidence interval from -0.81 to 0.58, and p = 0.745. The registry record does not flag a discrepancy between that analysis and any recalculation. However, it does not report a separate simple recalculated contrast for this continuous two-arm comparison.
The group estimates are least-squares means, while the inferential comparison is explicitly attributed to the LDA model. In general, a direct subtraction of group summaries is not necessarily equivalent to a longitudinal model’s estimated contrast, particularly when the model uses repeated measurements or other specified terms. The model details needed to reconstruct its result are not reported in the registry record.
Accordingly, the sponsor’s posted model result is the appropriate reported inferential comparison to quote. Its confidence interval includes zero, and its p-value is 0.745. These statistics describe the model-based comparison and its uncertainty; they do not establish equivalence, nor do they define clinical importance. The registry record does not report the complete statistical plan needed to assess every modeling choice independently.
11. Multiplicity, Missing Data and Analysis Populations
The registry lists 2 outcome measures and 2 analyses, while the posted results identify no secondary outcome results. The primary endpoint is change in HbA1c from baseline to Week 20. Other outcome results, if any, are not reported in the registry record. It is therefore not possible to assess how the primary comparison fits into a broader family of planned efficacy tests.
Multiplicity arises in general when several outcomes, time points, groups, or statistical tests are considered. If many comparisons are examined, the chance of obtaining a nominally unusual result can increase unless the analysis plan addresses that issue. The registry record does not report whether an adjustment for multiplicity was planned or used, whether the primary endpoint was selected before analysis, or whether other comparisons were designated as exploratory. No adjustment should be assumed.
The reported Full Analysis Set included randomized participants who took at least one dose of study drug and had a baseline or post-randomization measurement. The number of participants excluded from this population and reasons for any exclusions are not reported in the registry record. The group outcome results each list 34 participants, but that alone does not describe every stage of participant flow or establish whether every participant had a Week 20 measurement.
Details about missing outcome data are also not reported in the registry record. The record does not state how incomplete follow-up measurements were handled in the LDA model, whether imputation was used, or whether sensitivity analyses tested alternative missing-data assumptions. These details matter because estimates may depend on how incomplete data are treated, especially if missingness is related to outcome or group assignment.
The protocol’s sample-size justification, interim analyses, and full statistical analysis plan are not reported in the registry record. Consequently, the posted results cannot establish whether the trial was designed to detect a particular effect size, whether any interim decision rules existed, or whether the final analysis followed a prespecified multiplicity strategy. The p-value should be read as the p-value attached to the reported comparison, not as evidence that all design and analysis decisions are known.
12. 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 |
|---|---|---|---|
| Placebo | 1 | 34 | 2.9% |
| MK-0941 | 1 | 34 | 2.9% |
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 |
|---|---|
| Placebo | 13 of 34 |
| MK-0941 | 11 of 34 |
Most frequent serious adverse event terms
| Event term | Organ system | Placebo | MK-0941 |
|---|---|---|---|
| Abdominal pain upper | Gastrointestinal disorders | 0 of 34 | 1 of 34 |
| Hypoglycemia | Metabolism and nutrition disorders | 1 of 34 | 0 of 34 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Placebo | MK-0941 |
|---|---|---|---|
| Hypoglycaemia | Metabolism and nutrition disorders | 4 of 34 | 8 of 34 |
| Back pain | Musculoskeletal and connective tissue disorders | 2 of 34 | 2 of 34 |
| Headache | Nervous system disorders | 2 of 34 | 2 of 34 |
| Myalgia | Musculoskeletal and connective tissue disorders | 3 of 34 | 0 of 34 |
| Fatigue | General disorders | 2 of 34 | 0 of 34 |
| Insomnia | Psychiatric disorders | 0 of 34 | 2 of 34 |
| Nasopharyngitis | Infections and infestations | 2 of 34 | 0 of 34 |
| Pain in extremity | Musculoskeletal and connective tissue disorders | 0 of 34 | 2 of 34 |
Serious events with the highest arm-level rate: abdominal pain upper (2.9%), hypoglycemia (2.9%).
The registry reports serious adverse events for 1 of 34 participants in the placebo group and 1 of 34 participants in the MK-0941 group. It also reports other adverse events for 13 of 34 participants receiving placebo and 11 of 34 receiving MK-0941. These are counts of participants recorded as affected in each category, not measures of the primary HbA1c outcome.
The listed top serious adverse event terms are abdominal pain upper at 2.9% and hypoglycemia at 2.9%. The record does not identify which group is associated with each listed term, so those terms should not be assigned to a treatment group. Death counts are not reported in the registry record. The record also does not provide the full event-level descriptions, timing, duration, severity grading, or relatedness assessments needed for a detailed safety interpretation.
In general, adverse-event counts are descriptive. They do not by themselves establish whether a treatment caused an event or whether the groups differ reliably. With 34 participants reported in each group for the primary outcome, uncommon events may be poorly characterized. The safety figures should therefore be read as the events recorded in this trial, not as comprehensive estimates of risk or proof of a treatment-related effect.
13. What the Result Does, and Does Not, Mean
The result is an estimate of the difference in mean HbA1c change between randomized groups over the endpoint period from baseline on Day 1 to Week 20. The posted least-squares mean changes were -0.15 with placebo and -0.26 with MK-0941. The reported net mean difference was -0.11, with a 95% confidence interval from -0.81 to 0.58 and p = 0.745. The confidence interval includes zero, and the estimate is uncertain in both direction and magnitude.
This does not establish that the groups were identical. In general, failure to obtain a small p-value is not a demonstration of equivalence. Equivalence requires a prespecified margin and an analysis designed to assess whether the plausible difference lies within that margin; no such margin or equivalence analysis is reported in the registry record. The confidence interval also does not determine clinical importance without a threshold for meaningful change, which is not reported.
The result does not answer every question about MK-0941. It concerns the specified HbA1c measure and the Week 20 endpoint in the defined analysis population. It does not establish the effect on other clinical outcomes, longer-term outcomes, or populations beyond the adults with type 2 diabetes and inadequate glycemic control on insulin described in the registry record. Secondary outcome results are not reported in the registry record.
Nor does the primary endpoint result settle safety. The registry reports serious and other adverse-event counts, but the available summaries do not establish causation or characterize uncommon events in detail. Safety and efficacy are distinct questions and require their own interpretation.
The appropriate statistical reading is therefore limited: the registry reports modestly different point estimates across groups, alongside a wide confidence interval that includes zero and a p-value of 0.745. The posted data do not provide a precise estimate of the between-group difference, a clinical-importance threshold, or the information needed to conclude equivalence or broader benefit. This is a description of the evidence in the record, not medical advice.
14. Why This Trial Matters Statistically
This trial illustrates why a point estimate, confidence interval, and p-value should be read together. The group-level least-squares mean changes are -0.15 for placebo and -0.26 for MK-0941, while the reported model-based net difference is -0.11. Without the confidence interval, the point estimate would give little indication of the uncertainty. The 95% interval, from -0.81 to 0.58, includes zero and spans values in both directions.
The example also shows that a model-based comparison is not necessarily interchangeable with a simple calculation from group summaries. The outcome was measured over time, and the registry identifies an LDA model for the comparison. Because the complete model specification is not reported, readers should distinguish the sponsor’s reported inferential result from any hypothetical unadjusted reconstruction.
Analysis populations and missing-data procedures are part of statistical interpretation, not administrative details. The Full Analysis Set is defined, but participant flow, Week 20 completeness, and missing-data handling are not reported in the registry record. Without that information, readers cannot fully assess which observations informed the estimate or how sensitive the result might be to incomplete follow-up.
Finally, the study’s Phase IIa designation and enrollment of 68 participants frame the scale of the evidence. The record supports describing the posted outcome and its uncertainty, but not treating the p-value as a complete summary of the trial or extending the result to unreported outcomes. This is a useful example of separating what an analysis estimates from what its available precision and reporting can support.
15. 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 comparison is based on a relatively small trial record: 68 participants were enrolled, and the reported primary outcome groups each include 34 participants. The confidence interval for the net mean difference is wide and includes zero. The result is therefore not a precise estimate of the between-group difference. The registry record does not report a clinical-importance threshold that could help interpret the range of plausible effects.
The analysis is described as an LDA model, but its detailed specification is not reported in the registry record. Covariates, covariance structure, model diagnostics, and exact use of repeated measurements are not described. The posted Full Analysis Set definition is available, but the participant flow into that set and the handling of missing endpoint data are not reported. These gaps limit independent assessment of the modeling assumptions and robustness.
The record does not report the protocol’s sample-size justification, planned interim analyses, full statistical analysis plan, or multiplicity strategy. It also does not report secondary outcome results. Therefore, the primary p-value cannot be placed in the context of all planned comparisons, and the basis for the original design cannot be evaluated from this record alone.
The endpoint is change in HbA1c through Week 20. The record does not report longer-term primary outcome results or a clinical threshold for meaningful change. Safety reporting is similarly limited in the available summary: death counts are not reported, and the listed serious adverse event terms are not assigned to groups. Event-level details and follow-up duration for safety are not reported in the registry record.
These limitations do not invalidate the posted estimates. They define what can be concluded from the available record: the reported model comparison, its uncertainty, and the described analysis population, without stronger claims about clinical importance, equivalence, missing-data robustness, or longer-term outcomes.
16. Related Tutorials
17. Related Statistical Calculators
18. Sources
- ClinicalTrials.gov: A Study to Test MK-0941 in Adults With Type 2 Diabetes Mellitus With Inadequate Glycemic Control on Insulin (MK-0941-018) — NCT00824616.
- Registry record last updated 2015-07-28; status last verified 2015-07.
- Results first posted 2012-08-21.
- 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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19. Record Summary
The record describes a completed Phase IIa, multicenter, randomized, double-blind, placebo-controlled parallel-group trial of MK-0941 added to insulin in adults with type 2 diabetes and inadequate glycemic control. It lists 68 participants enrolled and reports 34 participants in each group for the primary outcome.
The primary endpoint was change in HbA1c from baseline on Day 1 to end of treatment at Week 20. Least-squares mean changes were -0.15 for placebo and -0.26 for MK-0941. The reported LDA model comparison was a net mean difference of -0.11, with a 95% confidence interval from -0.81 to 0.58 and p = 0.745.
The registry also reports serious and other adverse-event counts. Secondary outcome results, detailed missing-data methods, the full statistical plan, and a clinical-importance threshold are not reported in the registry record.