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 An Evaluation of Novel Glucose Sensing Technology on Hypoglycaemia in Type 1 Diabetes (IMPACT) (NCT02232698), a randomized na study. The primary outcome is Time Spent <70 mg/dL.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT02232698 |
| Phase | NA |
| Condition | Type 1 Diabetes Mellitus |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | None (open label) |
| Enrollment | 328 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Abbott Diabetes Care |
| Results posted | Yes |
2. Clinical Question
Population
Adults with type 1 diabetes using insulin were the intended study population. The registry lists type 1 diabetes mellitus as the condition and records enrollment of 328 participants. The primary-outcome description notes that 1 subject in the standard blood glucose monitoring group had no baseline sensor data and could not be included in the analysis of sensor data. The registry does not report further eligibility details, such as age criteria or duration of diabetes.
Intervention
The intervention was the Sensor Based Glucose Monitoring System, described as standard sensing system use for 6 months. The study was designed to assess whether this monitoring approach changed time spent below the glucose threshold used for the primary endpoint.
Comparator
The comparator was Standard Blood Glucose Monitoring. Participants assigned to this group were given blood glucose meters for monitoring during the 6 months study duration. The registry does not provide further details about monitoring instructions or how often participants were expected to test.
Primary question
The primary question concerned the difference between groups in time spent below 70 mg/dL, measured in hours per day. The endpoint description specifies assessment during days 194 to 208, with adjustment for baseline during days 1 to 15. The registry does not report a single numerical estimate or confidence interval for this primary comparison, so its direction and precision cannot be assessed from the record.
3. Trial Design
This was a randomized, parallel-group study with no masking reported in the registry. It compared the Sensor Based Glucose Monitoring System with Standard Blood Glucose Monitoring in adults with type 1 diabetes using insulin. The study is listed as completed, with enrollment of 328 participants. The sponsor was Abbott Diabetes Care. The registry records a start date of 2014-09 and primary completion in 2015-10.
The intervention description specifies standard sensing system use for 6 months. Participants assigned to the control group were given blood glucose meters for monitoring for the 6 months study duration. The registry does not report the allocation ratio, randomization sequence method, concealment procedures, or the detailed instructions given to participants and study staff. Masking is recorded as none, but the record does not explain which study roles, if any, were aware of assignment.
The primary endpoint was a continuous measure: time spent below 70 mg/dL, expressed in hours per day. The primary assessment period was days 194 to 208, and the comparison was described as adjusting for baseline measurements from days 1 to 15. The record identifies the summary measure as a mean with standard deviation. It also notes that one participant in the standard-monitoring group lacked baseline sensor data and could not be included in the analysis of sensor data.
Secondary outcomes included HbA1c at 6 Months; time spent below 55 mg/dL and below 40 mg/dL; frequency of episodes below 70 mg/dL, below 55 mg/dL and below 40 mg/dL; time spent above 180 mg/dL and above 240 mg/dL; time in range; number of glucose measurements; system utilisation; and change in Diabetes Treatment Satisfaction Questionnaire scores from Day 1 to Day 208. The registry lists 9 outcome measures and 13 analyses. A protocol, detailed statistical analysis plan, and explanation of how these outcomes were prioritized 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: A total of 328 subjects consented and enrolled into the study. Eighty-seven (87) of these failed screening or withdrew before randomisation. Two hundred and forty-one (241) subjects were randomised and 211 completed the study.
Overall Study
| Stage | Sensor Based Glucose Monitoring System | Standard Blood Glucose Monitoring |
|---|---|---|
| STARTED | 120 | 121 |
| COMPLETED | 110 | 101 |
| NOT COMPLETED | 10 | 20 |
Reasons for not completing this period:
| Reason | Sensor Based Glucose Monitoring System | Standard Blood Glucose Monitoring |
|---|---|---|
| Pregnancy | 1 | 1 |
| Met exclusion criteria | 1 | 1 |
| Had device-associated symptoms | 7 | 0 |
| Non-compliance with study device | 1 | 4 |
| Allocated to control group | 0 | 3 |
| Withdrawal by Subject | 0 | 11 |
Analysis population for the primary outcome, as defined in the registry: 1 subject from the standard blood glucose monitoring group had no baseline sensor data and could not be included in the analysis of sensor data.
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.
Population: 2 pregnant subjects (1 in each group) were excluded from all efficacy analysis (as stated in the protocol).
| Characteristic | Unit | Sensor Based Glucose Monitoring System | Standard Blood Glucose Monitoring | Total |
|---|---|---|---|---|
| Participants analysed | 119 | 120 | 239 | |
| Age, Continuous | years | 42.4 (SD 13.1) | 45.0 (SD 14.6) | 43.7 (SD 13.9) |
| Sex: Female, Male: Female | Participants | 42 | 61 | 103 |
| Sex: Female, Male: Male | Participants | 77 | 59 | 136 |
| Screening HbA1c | % | 6.73 (SD 0.52) | 6.74 (SD 0.59) | 6.74 (SD 0.56) |
| Screening HbA1c | mmol/mol | 50.1 (SD 5.7) | 50.2 (SD 6.5) | 50.1 (SD 6.1) |
6. Primary Endpoint
The registry lists the primary outcome as Time Spent <70 mg/dL, measured over Baseline and Days 194 to 208.
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | Standard Deviation |
| Unit | hours per day |
| Endpoint classification | Continuous Endpoint |
The primary endpoint measures the average amount of time per day that glucose readings were below 70 mg/dL. The registry expresses this quantity in hours per day and specifies a primary assessment window of days 194 to 208, compared with baseline measurements from days 1 to 15. The stated comparison is between the sensor-based monitoring group and the standard blood glucose monitoring group, adjusted for baseline.
In general, a continuous endpoint preserves information about the amount of time spent below the threshold rather than reducing the data to whether a participant did or did not cross it. It can therefore describe the extent of low-glucose exposure over the assessment period. A mean summarizes the group’s average value, while a standard deviation describes variation among participant values; these are different quantities and should not be read interchangeably.
The threshold is part of the endpoint definition, not a result. Likewise, the assessment windows describe when measurements were intended to represent baseline and follow-up; they do not establish what the observed group values were. The registry record does not report a single numerical estimate of the primary contrast, its confidence interval, or its statistical test result. The primary comparison’s magnitude, direction, and precision therefore cannot be described from the registry record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry defines a randomized comparison of sensor-based monitoring with standard blood glucose monitoring, but it does not report a single numerical estimate for the primary endpoint. The named endpoint is time spent below 70 mg/dL in hours per day, assessed during days 194 to 208 and described as adjusted for baseline during days 1 to 15. Without group estimates and an estimate of the between-group contrast, it is not possible to determine from the registry record whether the groups differed, in which direction, or by how much. A p-value or confidence interval for that contrast is also not reported in the registry record.
This absence matters for interpretation. The outcome name and assessment window identify what the study intended to compare, but they do not reveal the observed data. The registry’s record of means and standard deviations as the summary approach does not itself provide any means or standard deviations. Nor does the fact that the study was completed establish what the findings were. The primary outcome is described, but a single result is not available in the record.
The study also specified secondary outcomes covering HbA1c, other glucose thresholds, episode frequency, time in range, monitoring use, and treatment satisfaction. Those outcomes could provide complementary descriptions of glucose measurements and participant-reported experience. However, their names are not numerical findings. The registry record does not report estimates, uncertainty intervals, or test results for those secondary outcomes in the registry record for this analysis. It is therefore not possible to characterize their observed patterns or compare their strength of evidence.
The record identifies one participant in the standard-monitoring group who had no baseline sensor data and could not be included in the analysis of sensor data. This is a specific analysis-population note, not a complete account of missing data. The number of participants contributing to the primary analysis, the amount of missing follow-up data, and the handling of missing outcomes are not reported in the registry record. The implications of missing observations for the estimated comparison therefore cannot be assessed.
In general, a confidence interval communicates the range of effect estimates that are compatible with the data and the method used to calculate it. Its width conveys precision; it is not a guarantee that the true effect lies within the interval. Because no primary contrast or confidence interval is reported in the registry record, neither the estimated effect nor its precision can be evaluated. No conclusion about the primary endpoint should be inferred from the trial’s design description alone.
The registry includes serious adverse event counts and a short list of serious-event terms, but these are safety summaries and do not supply the missing primary outcome estimate. They should be read as separate information. Overall, the record establishes the question, groups, endpoint definition, and some study characteristics; it does not permit a statistical interpretation of the primary treatment contrast.
9. Statistical Methods Explained
The trial is described as randomized and parallel-group. In general, random assignment is intended to make comparison groups similar, on average, with respect to characteristics that could influence outcomes. Randomization does not ensure that every characteristic is balanced in a particular trial, and it does not replace reporting the analysis. The registry records no masking. It does not describe the randomization sequence, allocation concealment, or detailed procedures used to implement assignment.
What does the primary comparison estimate?
The endpoint is a continuous measure: time spent below 70 mg/dL, expressed as hours per day. The record says that the difference between intervention and control was assessed during days 194 to 208, adjusting for baseline during days 1 to 15. In general, a baseline-adjusted comparison accounts statistically for the baseline value when estimating the follow-up difference. The registry does not identify the model, the exact adjustment method, or the assumptions used for that analysis. It would therefore be inappropriate to name a particular regression model or claim that a specific model assumption was checked.
The registry identifies the summary parameter as a mean and the dispersion measure as a standard deviation. In general, the mean describes the average outcome, while the standard deviation describes how spread out individual observations are around that average. The standard deviation is not the standard error of the mean, and neither quantity alone is a between-group effect estimate. To interpret a comparison, readers need the group estimates and the estimated contrast, together with a measure of uncertainty. Those numerical primary results are not reported in the registry record.
How should uncertainty be understood?
In general, a confidence interval presents a range of values compatible with the observed data under the statistical procedure used. A narrower interval indicates greater precision than a wider one, all else equal. A confidence interval also helps distinguish a small estimated contrast with substantial uncertainty from a more precisely estimated contrast. The registry record does not report a confidence interval for the primary comparison, so its precision cannot be judged. The primary result’s p-value is also not reported in the registry record; statistical significance cannot be inferred from the outcome definition or study completion status.
General statistical interpretation should keep the estimate, uncertainty, and clinical context conceptually separate. The estimate describes the observed contrast; uncertainty describes how imprecisely it has been estimated; and substantive importance requires context beyond a test result. No numerical primary estimate is available to evaluate any of these dimensions. No clinical threshold for a meaningful difference is reported in the registry record.
Why do analysis populations matter?
The primary-outcome description says that 1 subject from the standard blood glucose monitoring group had no baseline sensor data and could not be included in the analysis of sensor data. This makes clear that at least one randomized participant was excluded from that analysis for the stated reason. The record does not say whether all other randomized participants were included, whether the analysis followed assigned groups regardless of actual monitoring use, or whether additional exclusions occurred. The analysis population and the handling of all missing data are not reported in the registry record.
In general, excluding participants can affect comparability if the reasons for exclusion relate to outcomes or differ between groups. Missing-data methods also require assumptions about why measurements are absent. Without details about follow-up completeness and the analysis approach, readers cannot assess whether the reported or intended estimate would be sensitive to missing observations. The record’s note about one baseline omission should not be treated as a full missing-data analysis.
What do the design and planning details establish?
The registry describes a randomized study with two parallel groups and 328 enrolled participants. It does not report an allocation ratio or sample-size justification. General sample-size planning depends on the target effect, outcome variability, significance level, desired power, allocation, and analysis method. Those design inputs and the original justification are not reported in the registry record, so the adequacy of the planned enrollment cannot be judged from this information.
The planning illustration described in the record is based on the observed effect, a two-sided significance level of 0.05, equal allocation, and a normal approximation; its effect to detect is a stated fraction of the observed effect. Such illustrations are not observed power and do not establish that the original design was based on those assumptions. The record’s description also distinguishes participant-per-arm planning for outcomes other than time-to-event outcomes, for which total event counts are used. No specific calculated sample-size illustration is included in the registry record.
In general, when outcome variation exceeds what a simple model assumes, over-dispersion can make model-based standard errors too small and confidence intervals too narrow unless the method accounts for it. This is a general concept, not a finding about this trial. The registry does not report a dispersion assessment or a model for count outcomes among the secondary measures. Likewise, it does not report interim analyses, stopping rules, or a detailed statistical analysis plan. Those elements should not be assumed to have been used or absent; they are not reported in the registry record.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists several secondary outcomes and records 13 analyses across 9 outcome measures. These include measures at different glucose thresholds, episode frequency, HbA1c, time in range, monitoring behaviour, and treatment satisfaction. Testing or estimating many outcomes can create a multiplicity concern: in general, the more comparisons considered, the greater the chance that some apparently notable findings arise by chance. How to interpret multiple results depends on whether outcomes were prespecified, which were primary or secondary, and whether any adjustment or hierarchy was used.
A multiplicity strategy, the full analysis plan, and any distinction between confirmatory and exploratory comparisons are not reported in the registry record. The available record also does not provide numerical secondary-outcome results, so the multiplicity issue cannot be evaluated against a set of observed findings. The primary outcome is described across specified time points, and the record notes that it was not reduced to a single comparison. No single numerical primary comparison is reported in the registry record.
The primary-outcome description identifies 1 participant in the standard-monitoring group who lacked baseline sensor data and could not be included in the sensor-data analysis. Further details about missing baseline or follow-up observations, reasons for missingness, and methods used to address missing data are not reported in the registry record. The record does not give the number analyzed for each outcome or state whether participants were analyzed according to their randomized assignment. These omissions limit assessment of the analysis population and the possible influence of missing data.
In general, complete-case analysis uses only participants with the measurements required for a particular analysis; other methods may use additional observed information under explicit assumptions. The registry does not identify which approach was used. It also does not report sensitivity analyses that might show whether conclusions depend on assumptions about missing values. Thus, the isolated note about a baseline omission should not be mistaken for a complete account of missingness or its treatment.
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 |
|---|---|---|---|
| Sensor Based Glucose Monitoring System | 4 | 120 | 3.3% |
| Standard Blood Glucose Monitoring | 4 | 121 | 3.3% |
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 |
|---|---|
| Sensor Based Glucose Monitoring System | 33 of 120 |
| Standard Blood Glucose Monitoring | 24 of 121 |
Most frequent serious adverse event terms
| Event term | Organ system | Sensor Based Glucose Monitoring System | Standard Blood Glucose Monitoring |
|---|---|---|---|
| hypoglycaemia | Metabolism and nutrition disorders | 2 of 120 | 3 of 121 |
| atrial fibrillation | Cardiac disorders | 1 of 120 | 0 of 121 |
| retroperitoneal haematoma | Gastrointestinal disorders | 1 of 120 | 0 of 121 |
| hyperglycaemia | Metabolism and nutrition disorders | 0 of 120 | 1 of 121 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Sensor Based Glucose Monitoring System | Standard Blood Glucose Monitoring |
|---|---|---|---|
| nasopharyngitis | Infections and infestations | 19 of 120 | 17 of 121 |
| influenza | Infections and infestations | 7 of 120 | 7 of 121 |
| medical device site reaction | General disorders | 10 of 120 | 0 of 121 |
Serious events with the highest arm-level rate: hypoglycaemia (2.5%), atrial fibrillation (0.8%), retroperitoneal haematoma (0.8%), hyperglycaemia (0.8%).
The registry lists serious adverse events for the two groups. In the Sensor Based Glucose Monitoring System group, 4 of 120 participants at risk were recorded as affected by serious adverse events. In the Standard Blood Glucose Monitoring group, 4 of 121 participants at risk were recorded as affected. These are counts reported for each group; they are not an estimate of a between-group effect and do not, by themselves, describe uncertainty or establish a difference.
The registry also reports other adverse events: 33 of 120 participants at risk in the sensor-based group and 24 of 121 participants at risk in the standard-monitoring group. The record does not explain the definitions or collection procedures for this category in the information. It also does not provide an adjusted comparison, confidence intervals, or a statistical test for these counts.
The listed serious-event terms and percentages are hypoglycaemia, 2.5%; atrial fibrillation, 0.8%; retroperitoneal haematoma, 0.8%; and hyperglycaemia, 0.8%. The registry does not identify group-specific percentages for these terms in the registry record. Death counts are not reported in the registry record. These safety summaries should be read separately from the primary glucose-time endpoint and should not be treated as evidence about its result.
12. What the Result Does, and Does Not, Mean
The registry record establishes that a randomized parallel-group study compared sensor-based glucose monitoring with standard blood glucose monitoring in adults with type 1 diabetes using insulin. It specifies time spent below 70 mg/dL, in hours per day, as the primary endpoint and identifies the baseline and follow-up assessment periods. It also records enrollment, study status, the monitoring approaches, and a note about one participant who lacked baseline sensor data.
Those design details do not establish the observed primary outcome. The registry record does not report a single numerical estimate of the primary comparison, a confidence interval, or a statistical test result. Consequently, the direction and size of the primary contrast, and the precision with which it was estimated, cannot be described. The endpoint threshold and its measurement units are definitions, not findings.
The registry lists secondary outcomes, including HbA1c, glucose time at other thresholds, episode frequency, time in range, monitoring measures, and treatment satisfaction. Listing an outcome does not show how participants performed on it. Numerical estimates and uncertainty for those outcomes are not reported in the registry record available for this analysis. No claim about the study’s results should be drawn from the outcome list alone.
The safety information is also limited to event counts and listed terms. Counts do not establish that risks differ between groups, and no comparative uncertainty estimates are reported. Deaths are not reported in the registry record. Interpretation of safety therefore remains descriptive and limited to the specific information recorded.
In general, a trial’s design explains how a question was intended to be studied, whereas its results describe what was observed and how uncertain the estimates are. A complete interpretation needs both. Here, the design and endpoint are described, but the numerical primary comparison is not. This record therefore supports explanation of the statistical question and its limitations, not a conclusion about the effect of either monitoring approach.
13. Why This Trial Matters Statistically
This trial is statistically relevant because it frames a continuous monitoring outcome as time spent below a defined glucose threshold, rather than only as an event count or a binary classification. A mean time-per-day measure can describe the average duration of low-threshold readings, while the standard deviation can describe variability among participants. The registry also specifies a baseline period and a later assessment period, making the intended comparison a baseline-adjusted follow-up contrast.
The design illustrates why endpoint definition and result reporting are both essential. Knowing the threshold, units, and time windows tells readers what quantity was intended for analysis. It does not show the observed group values, the difference between groups, or the uncertainty around that difference. In this record, the primary result is not reduced to one numerical comparison, and a single estimate with uncertainty is not reported. Readers can identify the statistical target but cannot evaluate its estimated magnitude or precision.
The range of listed secondary outcomes also highlights a common interpretive challenge. Different thresholds and outcome types can capture different aspects of glucose measurements, but multiple outcomes require clear prioritization and transparent reporting. The registry lists 9 outcome measures and 13 analyses, while the multiplicity strategy and detailed analysis plan are not reported in the registry record. That gap limits understanding of how a complete set of results would be interpreted.
Finally, the note about a participant without baseline sensor data demonstrates why analysis populations and missing observations matter even in a randomized study. Randomization concerns assignment; the analysis still needs to explain which participants contributed to each outcome and how incomplete measurements were handled. The registry does not report those details comprehensively. The statistical importance of the study is therefore not a claim about its findings, but the opportunity to see how endpoint definition, baseline adjustment, outcome multiplicity, and transparent result reporting shape interpretation.
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 principal limitation for interpreting this trial from the registry record is that a single numerical primary comparison is not reported. The primary endpoint is defined, but the group means, between-group estimate, confidence interval, and test result are not available in the information. The direction, magnitude, and precision of the primary finding therefore cannot be evaluated.
The registry lists multiple secondary outcomes and analyses, but numerical estimates for those outcomes and a multiplicity plan are not reported in the registry record. Without those details, it is not possible to distinguish confirmatory from exploratory analyses or assess how multiple comparisons were handled. The full statistical analysis plan and any interim analyses are also not reported in the registry record.
The primary-outcome description identifies 1 participant in the standard blood glucose monitoring group who lacked baseline sensor data and could not be included in the sensor-data analysis. The record does not state the full analysis population, the number contributing to each outcome, the completeness of follow-up, or how other missing observations were handled. It also does not provide details of the baseline-adjustment model, randomization implementation, or allocation ratio. These omissions constrain evaluation of the analysis and its assumptions.
The study is recorded as unmasked, but the registry does not explain which roles were aware of treatment assignment or how that might have affected outcome collection and monitoring behaviour. Further eligibility criteria and detailed measurement procedures are not reported in the registry record. Safety reporting is limited to counts and listed serious-event terms in the registry record; deaths are not reported in the registry record, and comparative uncertainty estimates are absent. These are limitations of the information available for interpretation, not proof that the unreported procedures or analyses did not occur.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: An Evaluation of Novel Glucose Sensing Technology on Hypoglycaemia in Type 1 Diabetes (IMPACT) — NCT02232698.
- Registry record last updated 2017-04-10; status last verified 2017-02.
- Results first posted 2017-04-10.
- 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 study sponsored by Abbott Diabetes Care. It enrolled 328 participants with type 1 diabetes mellitus and compared the Sensor Based Glucose Monitoring System with Standard Blood Glucose Monitoring. The monitoring period was 6 months.
The primary endpoint was time spent below 70 mg/dL, measured in hours per day, with assessment during days 194 to 208 and baseline adjustment using days 1 to 15. The registry notes that 1 participant in the standard-monitoring group lacked baseline sensor data and could not be included in the sensor-data analysis. It lists 9 outcome measures and 13 analyses, including glucose, HbA1c, monitoring, and treatment-satisfaction outcomes.
A single numerical estimate of the primary comparison, its confidence interval, and its test result are not reported in the registry record. The detailed statistical plan, multiplicity approach, and comprehensive handling of missing data are also not reported in the registry record. Serious adverse event counts are listed for both groups, but deaths are not reported in the registry record.