The Effectiveness of Intervention on Insulin Injection: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for The Effectiveness of Intervention on Insulin Injection (NCT03324451), a non-randomized na study. The primary outcome is Change in Glycosylated Hemoglobin (HbA1c) Levels.

2. Clinical Question

The question concerns a behavioral intervention intended to support insulin initiation, not a direct comparison of insulin products or doses. HbA1c is the primary endpoint named in the registry record; its interpretation would depend on the observed values, their variability, and the analysis used to compare groups. Those numerical results and analysis details are not reported in the registry record. Therefore, the clinical question can be stated, but the available registry information does not show whether the groups differed in HbA1c change or how precisely any difference was estimated.

3. Trial Design

This completed study is registered as NCT03324451 and is titled The Effectiveness of Intervention on Insulin Injection. Its official title describes an application of the Transtheoretical Model for insulin-naïve patients with type 2 diabetes. The registry lists enrollment of 151 and a parallel-group design. The listed start date is 2018-03-01, and the primary completion date is 2020-03-01.

Allocation is listed as non-randomized, and masking is listed as none. The intervention arm received the TTM Intervention for Insulin Initiation, described as individual intervention plus insulin injection follow-up management. The control arm received usual care from the hospital hosting that arm, including regular patient education. The registry also explicitly cautions that this is not a randomized comparison and that the arms are not a like-for-like control comparison.

That distinction matters for interpretation. Without random assignment, the groups may differ in ways that also relate to HbA1c change. The registry record does not describe the allocation procedure, the reasons participants entered one arm rather than the other, or any methods used to address baseline differences. It is therefore not possible from this record to determine whether measured or unmeasured group differences were accounted for.

The primary outcome is change in HbA1c, measured at baseline and 12 months after the intervention. Other listed outcomes are changes in Diabetes Empowerment Process, Diabetes Distress, Quality of Life, and Body Mass Index. The record lists five outcome measures in total and zero analyses. It does not report a statistical analysis plan, a sample-size justification for the trial itself, or whether any interim analyses were planned.

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

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 Glycosylated Hemoglobin (HbA1c) Levels, measured over At baseline and 12 months after the intervention.

The primary endpoint is change in glycosylated hemoglobin (HbA1c) levels, expressed in percent of glycosylated Hb. The registry describes HbA1c as collected from a blood test and specifies measurement at baseline and 12 months after the intervention. HbA1c is used in clinical research as a continuous measure of glycemic status, making it suitable for assessing change over time rather than simply classifying participants into event categories.

A change endpoint requires a clear definition of how the baseline and follow-up values are combined, such as whether the analysis compares each participant’s change or compares follow-up values while accounting for baseline. The exact analysis approach is not reported in the registry record. Nor are the group means, standard deviations, changes, or between-group estimate reported, so the size and direction of any difference cannot be described from this record.

For a continuous outcome, a group average gives a summary of the central tendency, while a standard deviation describes variation among observations. Both are relevant to understanding the endpoint, but the registry record does not include numerical results for either group. The named endpoint and measurement times identify what the study intended to assess; they do not, on their own, establish what happened to HbA1c or whether a difference between arms was estimated precisely.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

Statistical methods help translate measurements into estimates and describe how much uncertainty surrounds those estimates. The registry record names a continuous primary endpoint measured at baseline and 12 months, but does not report an analysis method or the resulting estimates. The explanations below describe general statistical concepts; they are not claims about methods used in this study.

What does a mean summarize?

For a continuous measure such as HbA1c, the mean is the arithmetic average of observed values. A mean can describe the average outcome in a group or the average change within a group. It does not show how similar or different individual participants’ values were. The primary outcome is specified as a mean, with standard deviation as the dispersion measure, but numerical group means and standard deviations are not reported in the registry record.

The standard deviation describes the spread of individual values around a group mean. A relatively broad spread means participants’ measurements vary more, while a narrower spread means measurements are more clustered. It is not the same as the standard error, which describes the uncertainty of an estimated mean. Both the variability in observations and the number of observations contribute to the precision of an estimate.

Why distinguish change within groups from a difference between groups?

A group’s average change from baseline describes what happened within that group. The intervention question, however, concerns whether change differs between the intervention and control groups. A change in both groups could occur for many reasons, including usual care, participant characteristics, or changes over time. Comparing the groups’ changes is therefore not the same as showing that an intervention caused a change.

There are several possible ways to analyze baseline and follow-up measurements, including comparing individual changes or modeling follow-up values while accounting for baseline. These approaches can yield different estimates and rely on different assumptions. The registry record does not identify which approach was used, so no particular method should be attributed to the study.

What does a confidence interval communicate?

In general, a confidence interval gives a range of values compatible with the data under a specified statistical procedure and its assumptions. It communicates precision as well as a plausible range for an estimated effect; a narrow interval indicates greater precision than a wide interval. A confidence interval is not reported for the primary endpoint in the registry record. There is therefore no interval from which to assess precision or to distinguish a well-estimated small difference from an uncertain estimate.

A p-value, when reported, assesses how unusual the data would be under a specified null hypothesis and statistical model. It does not measure the probability that the null hypothesis is true, the size of an effect, or its clinical importance. No primary outcome p-value is reported in the registry record. Without the estimate and its uncertainty, a threshold-based conclusion would be especially uninformative.

Why does non-randomized allocation matter?

In a non-randomized study, differences between groups may be related to who entered each group, their health status, their care setting, or other factors. If such factors are associated with both group membership and outcome, a simple group comparison may combine intervention effects with those differences. Statistical adjustment can address measured factors when suitable data and methods are available, but it cannot automatically remove bias from unmeasured factors. The registry does not report an adjustment strategy, covariates, or an adjusted estimate. It also warns that the arms are not a like-for-like comparison.

Parallel-group design means the arms are followed as separate groups rather than participants crossing from one study treatment to another. This design label alone does not ensure comparability; in this study, the non-randomized allocation remains important when interpreting any comparison.

What does over-dispersion mean in general?

Over-dispersion arises when observed variation is greater than a statistical model expects. It is most often discussed for count outcomes, where a simple model may underestimate variability and consequently overstate precision. The primary outcome in this study is continuous, and the registry record does not report a model or an over-dispersion assessment. The concept is general and should not be taken to mean that over-dispersion was observed in this study.

How should sample-size illustrations be understood?

Sample-size planning asks how many participants would be needed to detect a chosen effect under stated assumptions. The registry’s planning illustration is described as based on the observed effect, with a two-sided significance level of 0.05, equal allocation between arms, and a normal approximation. It considers effects defined as stated fractions of the observed effect. For non-time-to-event outcomes, the stated convention is participants per arm. These are planning assumptions, not a report of the trial’s observed power, and not evidence that the study was designed using those assumptions.

The computed sample-size quantities and the observed effect used for that illustration are not reported in the registry record. A planning calculation based on an observed effect is also dependent on the reliability of that observed estimate. It should not be interpreted as proof that the study could detect an effect of a particular size, especially when the primary analysis estimate and its uncertainty are not reported.

10. Confidence Intervals for Each Arm

No two-arm comparison is shown for this trial, but each arm's mean can be given with a t-based 95% confidence interval computed from the posted mean, spread and number of participants.

R code and output

arm <- c("Intervention Arm", "Control Arm")
n   <- c(65, 41)
m   <- c(-1.47, -2)
sp  <- c(2.23, 2.29)
sd  <- sp      # posted standard deviations
for (i in seq_along(n)) {
  se <- sd[i] / sqrt(n[i]); h <- qt(0.975, n[i] - 1) * se
  cat(sprintf("CARM|%s|%d|%.3f|%.3f|%.3f|%.3f\n", arm[i], n[i], m[i], sd[i], m[i] - h, m[i] + h))
}

CARM  Intervention Arm  65  -1.470  2.230  -2.023  -0.917
CARM  Control Arm  41  -2.000  2.290  -2.723  -1.277

11. Multiplicity, Missing Data and Analysis Populations

The registry record lists five outcome measures: change in HbA1c, Diabetes Empowerment Process, Diabetes Distress, Quality of Life, and Body Mass Index. When a study examines multiple outcomes or multiple time points, the chance of obtaining at least one apparently notable result can increase. Statistical plans may address this through a prespecified hierarchy, adjusted testing, or a clear distinction between primary and secondary outcomes. The registry identifies a primary endpoint, but does not report whether or how multiplicity was handled.

Missing-data methods can also affect interpretation. If some participants lack a follow-up measurement, an analysis may use complete cases, imputation, or another approach; each relies on assumptions. The registry record does not report the number of participants with primary outcome measurements, the amount or pattern of missing data, or any method for handling missing values. It does not report an analysis population or whether participants were analyzed according to a prespecified rule.

These omissions matter because the endpoint is measured at baseline and 12 months after the intervention. Without follow-up completeness and analysis-population details, it is not possible to assess whether the analyzed participants represent those enrolled or how missing measurements may have affected the estimates. The registry lists zero analyses, so there are no posted analysis results against which to evaluate multiplicity or missing-data decisions.

The statistical plan, any prespecified outcome hierarchy, and analysis-population definitions are not reported in the registry record. These details should not be inferred from the endpoint list or the study design description.

12. Safety Results

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

Deaths

Other (non-serious) adverse events

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

The registry lists serious adverse event counts of zero in the TTA Intervention group, with 97 participants at risk, and zero in the Control Arm, with 54 participants at risk. It also lists zero deaths in each group, with the same respective numbers at risk. These are the posted counts for the categories shown in the record.

A zero count means that no event was recorded in that category for the listed group in this registry record. It does not prove that the intervention is free of risk, and it does not establish that the groups had equivalent safety. The record does not report a statistical comparison of safety outcomes or a confidence interval for the event counts. It also does not give details about event definitions, ascertainment, follow-up completeness, or whether events were assessed as related to the intervention.

The record lists no top serious-event terms. It separately reports zero other adverse events in both groups. These figures should be read as registry entries rather than as a comprehensive account of every possible symptom or adverse experience. Because the study was non-randomized, any comparison between groups would also need to account for differences in who entered each arm and how they were followed.

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

The record establishes that a completed, non-randomized, parallel-group study evaluated a Transtheoretical Model intervention for insulin initiation in insulin-naïve patients with type 2 diabetes. It identifies the intervention components, the usual-care comparator, total enrollment, and a primary endpoint of HbA1c change from baseline to 12 months after the intervention. It also lists secondary outcomes and safety counts.

What the record does not establish is the size or direction of any HbA1c change, whether the arms differed, or how precisely a difference was estimated. Primary outcome means, standard deviations, between-group estimates, confidence intervals, and p-values are not reported in the registry record. The record lists zero analyses. This is not equivalent to a finding of no effect; it means that the relevant analysis result is not reported in the registry record.

The design also limits causal conclusions. Because allocation was non-randomized and the registry cautions that the arms are not a like-for-like comparison, observed differences could reflect group characteristics as well as the intervention. The record does not report methods that would allow readers to judge whether such differences were addressed.

The sample-size illustration is a planning exercise based on the observed effect and stated assumptions, not a measure of the trial’s observed power. It cannot substitute for the missing outcome estimate or quantify how much uncertainty surrounds the result. Likewise, zero listed serious adverse events and deaths should not be interpreted as proof of no risk or as a complete safety assessment.

Thus, the registry record is informative about the study question and design, but not about the primary efficacy result. No claim that the intervention did or did not change HbA1c relative to usual care is supported by the posted outcome information.

14. Why This Trial Matters Statistically

This study raises a useful statistical question about how an intervention supporting insulin initiation might be evaluated using a continuous clinical measure. The endpoint is defined at two time points, and the record distinguishes an intervention combining individual support with follow-up management from usual care that includes regular patient education. Describing these features clarifies what a comparison is intended to address.

At the same time, the non-randomized allocation demonstrates why design information is essential alongside outcome values. A numerical difference between groups would not, by itself, isolate an intervention effect if groups differed before treatment or entered care through different processes. Readers need both an estimate and enough information about allocation and analysis to judge the credibility of the comparison.

The record also illustrates the importance of complete result reporting. Naming HbA1c as the primary endpoint is not enough to understand the findings: readers need the group results, an estimate of the between-group difference, and an indication of precision. Reporting analysis populations and missing-data handling would further clarify which participants contribute to the estimate and what assumptions support it.

Finally, safety counts require context. Zero recorded events can be informative, but interpretation depends on how events were defined, collected, and followed. The registry’s design and outcome listings make the study question identifiable, while the absence of outcome analyses leaves effectiveness and precision unresolved.

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.

Several limitations are specific to the registry information for this study. Allocation is non-randomized, and the registry explicitly states that the arms are not a like-for-like control comparison. The record does not explain how participants were assigned to arms or report whether baseline differences were measured and addressed. As a result, causal interpretation of any group difference would be limited even if outcome estimates were available.

The primary endpoint is specified, but numerical results are not reported. The record lists zero analyses and does not provide group means, standard deviations, changes, between-group estimates, confidence intervals, or p-values. It is therefore not possible to assess effect size, direction, precision, or statistical compatibility with different possible effects.

Details needed to assess the analysis are also absent. The registry does not report a statistical analysis plan, outcome hierarchy, multiplicity approach, missing-data method, analysis population, or the number of participants with 12-month measurements. It does not report a sample-size justification for the trial itself. The separate planning illustration should not be confused with evidence about the original design or observed power.

The record lists serious and other adverse-event counts but does not describe how events were defined or collected, the duration and completeness of safety follow-up, or any assessment of relatedness. These limitations concern what can be concluded from the registry record; they do not establish that the study did not collect additional information.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: The Effectiveness of Intervention on Insulin Injection — NCT03324451.
• Registry record last updated 2020-09-16; status last verified 2020-09.
• Results first posted 2020-09-16.
• 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.

19. Record Summary

NCT03324451 is a completed, non-randomized, parallel-group study of a Transtheoretical Model intervention for insulin-naïve patients with type 2 diabetes. Total enrollment was 151. The intervention included individual intervention and insulin injection follow-up management; the control arm received usual care, including regular patient education. Masking is listed as none.

The primary endpoint was change in HbA1c, measured at baseline and 12 months after the intervention. Four secondary outcomes are listed: changes in Diabetes Empowerment Process, Diabetes Distress, Quality of Life, and Body Mass Index. The record lists five outcome measures and zero analyses. Primary outcome estimates and their precision are not reported in the registry record.

The registry lists zero serious adverse events, other adverse events, and deaths in both groups. It also cautions that the non-randomized arms are not a like-for-like control comparison. The design and intended question are described, but the posted results do not establish the direction or magnitude of an HbA1c difference.