Use of the FreeStyle Navigator Continuous Glucose Monitoring System to Enhance Education and Glycaemic Control: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Use of the FreeStyle Navigator Continuous Glucose Monitoring System to Enhance Education and Glycaemic Control (NCT01214824), a na na study. The primary outcome is Change in HbA1C From Baseline to 6 Months.

2. Clinical Question

3. Trial Design

The registry record describes a completed, single-group device study sponsored by Abbott Diabetes Care. It lists 32 participants and identifies the FreeStyle Navigator Continuous Glucose Monitoring System as the intervention. The study start is recorded as 2010-11 and primary completion as 2012-02. Phase is listed as NA, allocation as NA, and masking as NONE. These entries describe the registry classification; they do not supply a fuller account of the conduct or analysis.

Because this was a single-group study, the primary outcome is framed as a change over time within the study population rather than a contrast between randomized groups. The baseline measurement provides a reference for the later measurement, but it cannot by itself account for other changes over time. There is no separate untreated or alternative-treatment group identified in the registry record. Accordingly, the posted design does not support a direct randomized treatment comparison.

The registry summary states an aim of demonstrating whether short or intermittent use of continuous glucose monitoring could support better longer-term glycaemic control and HbA1c in patients with persistent poorly controlled diabetes. That statement describes the intended question, not a result. Device-use schedule, education procedures, visit schedule, adherence measures, and any co-interventions are not reported in the registry record. The protocol’s sample-size justification, detailed analysis plan, and interim-analysis plans are also not reported in the registry record.

The primary outcome is specified for an intention-to-treat analysis, but the registry record does not explain how that population was defined in practice or how participants without complete measurements were handled. It records four outcome measures and two analyses. The listed secondary outcomes concern a reduction in HbA1c of > or = 0.5% and proportions of time in hypoglycaemia under masked and unmasked conditions. Numerical results for those outcomes 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

Analysis population for the primary outcome, as defined in the registry: Intention to treat analysis

5. Baseline Characteristics

The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.

6. Primary Endpoint

The registry lists the primary outcome as Change in HbA1C From Baseline to 6 Months, measured over Baseline and 6 months.

The primary endpoint is mean change in HbA1c from baseline to 6 months, expressed in HbA1c %. The registry description defines the change as the 6-month measurement minus the baseline measurement and identifies the intention-to-treat population. It also identifies the mean as the measure of central tendency and the standard deviation as the dispersion measure. The actual means, change estimate, and standard deviation values are not reported in the registry record.

HbA1c is used as a measure of longer-term glycaemic control, which makes it relevant to the study’s stated interest in whether short or intermittent monitoring could be followed by longer-term change. The endpoint therefore focuses on a clinical measure at two time points rather than on glucose readings at a single moment. The record does not give the laboratory procedures, timing windows, or rules for handling measurements outside the planned timeframe.

In general, a mean change conveys the average direction and size of within-population change, while the standard deviation describes how much individual observations vary around a mean. Neither alone establishes why change occurred. In a single-group before-and-after study, a change from baseline may reflect the intervention, other events over time, or a combination. Without a numerical estimate and uncertainty measure in the registry record, the primary endpoint’s observed magnitude and precision cannot be assessed.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry identifies the primary outcome as a continuous measure summarized by a mean, with standard deviation as the dispersion measure. It defines the endpoint as change in HbA1c from baseline to 6 months and specifies the intention-to-treat population. Those details identify the kind of quantity being assessed, but they do not reveal the numerical result or all steps of the statistical analysis. The exact statistical test or model, handling of incomplete measurements, and confidence-interval method are not reported in the registry record.

What does a mean change represent?

In general, a mean change is the average of the participant-level changes included in an analysis. A positive or negative value would be interpreted in light of how change was defined; this record defines it as the 6-month value minus baseline. The mean can summarize the overall direction of change, but it may not describe every participant’s experience. Participants can have changes that differ in size or direction while the average gives a single summary.

In general, standard deviation describes spread among observations, not uncertainty in the mean itself. A larger standard deviation indicates more variation in the observations around their mean. The standard deviation and the standard error answer different questions: the former describes observed spread, while the latter describes sampling uncertainty in an estimated mean. The registry record identifies standard deviation as the dispersion measure but does not report its value. No standard error is reported either.

Why does the single-group design matter?

In general, comparing measurements from the same participants over time can account for stable differences between those participants, but it does not create a control group. The observed change can be described as a temporal change in the study population. Without a concurrent comparison, that change cannot be separated from other influences that may also vary over time. This distinction matters when interpreting an intervention intended to affect a later measurement.

A baseline measurement is useful for defining the starting reference and for calculating change. It does not show what would have happened over the same period without the intervention. In general, a randomized concurrent group can help estimate that counterfactual comparison by balancing factors between groups, although no such group is identified in this record. The registry lists allocation as NA and the model as single-group.

How should uncertainty be understood?

In general, a confidence interval expresses uncertainty around an estimate under a specified statistical method and its assumptions. A narrow interval indicates greater precision than a wide interval, but an interval does not correct biases arising from study design or missing data. A p-value addresses compatibility between data and a stated null hypothesis under a model; it is not the probability that the hypothesis is true and does not indicate the practical importance of an effect. The primary confidence interval and p-value are not reported in the registry record.

The sample-size assumptions recorded for planning illustrations include a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. The assumed effect to detect is described as a stated fraction of the observed effect. These are planning assumptions, not evidence that the trial itself used a two-arm design: the trial is recorded as single-group. The planning illustrations are not observed power, and their sample-size figures should not be mistaken for participant counts actually enrolled. The registry record does not report the trial’s own sample-size justification.

What can be inferred from the outcome descriptions?

The record lists four outcome measures and two analyses. The primary measure is continuous HbA1c change. The secondary outcomes include the number of subjects whose HbA1c reduction was > or = 0.5%, and proportion of time in hypoglycaemia under masked and unmasked conditions, with the threshold specified as <3.9 mmol/L. An outcome definition says what is intended to be measured; it does not supply the result. The secondary numerical findings are not reported in the registry record.

In general, analyses of proportions or counts require attention to how many participants contributed data and how repeated observations are treated. Proportions of time may also depend on the period observed and the measurement process. The record does not describe those details, so no particular model or calculation method can be attributed to these secondary outcomes. The primary outcome is identified as a mean, but its full estimation procedure is not reported.

What are the limits of the posted analysis details?

The intention-to-treat label indicates the population specified for the primary analysis. In general, intention-to-treat analysis aims to retain participants in the groups to which they were assigned, but this study has no randomized comparison group and the registry does not explain the operational definition used. It also does not report how missing measurements, withdrawals, or protocol deviations were handled. No assumptions about those procedures should be inferred.

Likewise, the registry does not report whether the analysis adjusted for baseline HbA1c or other variables, whether any sensitivity analyses were conducted, or whether interim analyses were planned. Without the effect estimate and its uncertainty, the posted statistical details cannot establish whether the change was distinguishable from sampling variation. The reported design and endpoint can be described, but the unreported outcome and analysis details limit further statistical interpretation.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists four outcome measures and two analyses. The primary endpoint is change in HbA1c from baseline to 6 months; the listed secondary outcomes include an HbA1c reduction of > or = 0.5% and proportion of time in hypoglycaemia under masked and unmasked conditions. The record does not identify a hierarchy among the secondary outcomes, a multiplicity adjustment, or a prespecified strategy for interpreting several outcomes together. Those details are not reported in the registry record.

In general, when multiple hypotheses are tested, the chance of at least one apparently unusual result can increase if each is interpreted separately without accounting for the number of tests. Adjustment methods or a prespecified hierarchy can address that issue, but no such approach can be attributed to this study from the registry information. Since numerical results and p-values are not reported, the impact of multiplicity on interpretation cannot be assessed.

The primary analysis population is identified as intention to treat. The registry does not report the number with outcome data at each time point, the amount or pattern of missing data, or the method used to address missing measurements. It also does not report whether any sensitivity analyses assessed the consequences of missingness. In general, missing-data methods rely on assumptions, and different assumptions can affect estimates. The available information is insufficient to judge which assumptions or methods were used.

Interim analyses, stopping rules, and the detailed statistical analysis plan are not reported in the registry record. Their absence from the record should not be treated as evidence that a particular procedure was or was not used.

11. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 0% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: right iliac fossa pain (3.1%), unresolving paronychia (3.1%), viral meningitis (3.1%).

The registry records an intervention group with 32 at risk for serious adverse events and 3 affected. It lists Right iliac fossa pain, Unresolving Paronychia, and Viral Meningitis, each with a recorded percentage of 3.1%. These are the serious adverse event terms and percentages reported for the group. The registry does not provide further event narratives, timing, duration, outcome, or an assessment of whether an event was related to the device.

The three term-specific percentages should be read as listed, not added together. The record does not say whether the listed terms occurred in distinct participants or whether an individual could contribute more than one term. It therefore does not support an inference about the total number of unique participants represented by those terms beyond the group-level affected count.

Deaths are recorded as null, which means death information is not reported in the registry record; it should not be interpreted as a confirmed count of zero. In general, serious adverse event counts describe events captured under the study’s reporting definitions and observation period. They do not by themselves establish causation or provide a complete comparison of safety between treatments. There is no separate control group identified in this single-group study, and the registry does not report a comparative safety analysis.

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

The record identifies a completed single-group study of the FreeStyle Navigator Continuous Glucose Monitoring System and a primary endpoint focused on mean HbA1c change from baseline to 6 months. Enrollment was 32. These registry entries describe the study’s scope and design, but the numerical primary result is not reported in the registry record. It is therefore not possible to state whether the mean changed, in which direction, by how much, or with what precision.

The registry summary describes an intended question about whether short or intermittent continuous glucose monitoring could support longer-term glycaemic control and HbA1c. An intended research question is not a finding. The device is identified as the intervention, but its actual use pattern, adherence, and accompanying educational procedures are not reported in the registry record. The result cannot be attributed to any specific amount or pattern of device use from the information available.

In general, a single-group before-and-after study can document change among measured participants, but it cannot determine how much of that change was caused by the intervention. Other changes over time may contribute. A randomized control comparison is not identified here, so the record does not provide a direct estimate of a difference between intervention and control groups.

The secondary outcome definitions indicate that the study also considered a specified HbA1c reduction and time in hypoglycaemia under masked and unmasked conditions. Their numerical results are not reported in the registry record. Those definitions do not establish that outcomes improved or worsened. The record also does not provide enough information to assess missing-data handling, multiplicity, or the precision of secondary estimates.

The appropriate statistical reading is therefore limited: the registry specifies a clinical question, a single-group design, and an HbA1c endpoint, but does not provide the outcome values needed to evaluate the observed effect. No conclusion about effectiveness or lack of effectiveness follows from the missing numerical result.

13. Why This Trial Matters Statistically

This study is statistically instructive because its stated aim concerns a longer-term outcome, while the intervention is described as short or intermittent use of continuous glucose monitoring. That framing raises a question about whether a brief or intermittent exposure might be followed by a later change in HbA1c. The registry record identifies the intended question and the measurement interval, but does not report the outcome value needed to assess the observed change.

The single-group structure also illustrates the distinction between measurement and causal comparison. Repeated measurement can show how the study population changed over time, but a baseline value does not represent the outcome participants would have had without the intervention. In general, a control group helps distinguish intervention-associated change from other influences. No concurrent comparator is identified in this record.

The listed outcome set includes a continuous primary measure, an HbA1c threshold outcome, and hypoglycaemia proportions in masked and unmasked conditions. These outcomes represent different statistical summaries and can answer different questions. In general, multiple outcomes make a prespecified analysis strategy important, especially when findings are interpreted together. The registry does not report such a strategy or numerical results for these outcomes.

The record also highlights why an endpoint definition and an analysis result are not interchangeable. It specifies the measure, timeframe, population, and summary type for the primary outcome, yet omits the estimate and uncertainty. Without those values, neither magnitude nor precision can be judged. The study is therefore useful for understanding how design, endpoint specification, and complete reporting each shape what can be learned from a clinical trial record.

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 limitation specific to interpreting this study is the absence of numerical primary outcome results in the registry record. Although the endpoint and timeframe are defined, the baseline and 6-month means, mean change, standard deviation, and uncertainty estimates are not reported. The record therefore does not allow assessment of the magnitude or precision of the primary outcome. Numerical results for the listed secondary outcomes are also not reported.

The single-group design limits interpretation of change as an intervention effect. There is no concurrent comparator, and allocation is listed as NA. In general, a before-and-after comparison cannot separate intervention-associated change from other changes occurring during the same period. This is especially important when interpreting a longer-term outcome after a device-use period whose details are not reported.

Further study details are limited in the registry record. Eligibility criteria beyond the broad description, device-use schedule, adherence, educational procedures, co-interventions, and measurement procedures are not reported. The primary population is labeled intention to treat, but the handling of missing measurements, withdrawals, and protocol deviations is not described. The detailed statistical analysis plan, sample-size justification, interim analyses, and multiplicity strategy are not reported either.

The serious adverse event listing provides terms and percentages, but not event narratives or an assessment of relationship to the device. Death information is not reported in the registry record. Since there is no control group, the posted safety information does not supply a comparative estimate. These reporting and design constraints limit conclusions about both outcome changes and their attribution.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Use of the FreeStyle Navigator Continuous Glucose Monitoring System to Enhance Education and Glycaemic Control — NCT01214824.
• Registry record last updated 2013-07-02; status last verified 2013-06.
• Results first posted 2013-06-06.
• 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.

18. Record Summary

NCT01214824 is recorded as a completed, single-group device study sponsored by Abbott Diabetes Care. The intervention was the FreeStyle Navigator Continuous Glucose Monitoring System, and enrollment was 32. The registry lists the start as 2010-11 and primary completion as 2012-02. Allocation is NA, masking is NONE, and phase is NA.

The primary outcome is mean change in HbA1c from baseline to 6 months in the intention-to-treat population. The registry specifies standard deviation as the dispersion measure but does not report the numerical primary result or its uncertainty. Listed secondary outcomes concern an HbA1c reduction of > or = 0.5% and proportion of time in hypoglycaemia under masked and unmasked conditions.

One intervention group is listed for serious adverse events, with 32 at risk and 3 affected. Three serious event terms are listed, each at 3.1%. Death information is not reported in the registry record. The single-group design and absent outcome estimates limit assessment of effect magnitude, precision, and causality.