The Aging Endocrine Pancreas: Characterization of the Entero-insular Axis Physiology in the Elderly: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for The Aging Endocrine Pancreas: Characterization of the Entero-insular Axis Physiology in the Elderly (NCT00843479), a registered phase not stated study. The primary outcome is Homeostasis Model Assessment Insulin Resistance (HOMA-IR) Index.

2. Clinical Question

3. Trial Design

This is a completed clinical study sponsored by the University of Campinas, Brazil. The registry lists enrollment of 24. Its stated focus is characterizing the entero-insular axis in elderly participants in relation to middle-age participants. The record describes two groups: elderly normoglycemic subjects aged 65-80 years and middle-age normoglycemic subjects aged 35 to 50 years.

The registry does not describe a treatment assignment. It explicitly notes that this is not a randomized comparison, that allocation is not stated, and that the arms are not a like-for-like control comparison. This matters for interpretation: the principal contrast is between age-defined groups, not between randomly assigned treatments. Differences between groups cannot automatically be attributed to age alone, because the record does not provide information that would establish balance on other characteristics.

The planned assessments include a meal tolerance test for incretin hormone measurements and a hyperglycemic clamp followed by an arginine test for beta-cell function and acute insulin response. Body composition and basic biochemistry are also described. The primary outcome is HOMA-IR, with measurement specified within 1 month from the screening visit. Secondary outcomes include serum DPP-IV concentration and GLP-1 area under the curve.

The registry gives a start date of 2009-06, a primary completion date of 2010-09, and a status of completed. It does not report detailed eligibility criteria, recruitment procedures, allocation procedures, masking, protocol deviations, or the statistical analysis plan. Those features should not be inferred from the study title or the description of the assessments.

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: Cross-sectional study conducted with 24 non-obese patients with normal glucose tolerance. Two groups formed: middle-aged (n=12) and aged(n=12). They were healthy and had no significant illness. None were taking drugs that affect insulin sensitivity/secretion or incretin hormones.

Overall Study

Analysis population for the primary outcome, as defined in the registry: minimum number required to find a significant difference between groups considering the intra-subject variation

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 Homeostasis Model Assessment Insulin Resistance (HOMA-IR) Index, measured over within 1 month from screening visit.

The primary endpoint is the Homeostasis Model Assessment Insulin Resistance index, or HOMA-IR. The registry describes it as a calculated index using glucose and insulin: glucose multiplied by insulin, divided by 22.5. Glucose is expressed in mmol/L and insulin in milli-units per liter. The record states that higher HOMA-IR values indicate lower insulin sensitivity.

As a continuous measure, HOMA-IR can describe variation across participants rather than reducing the result to a simple category. The registry specifies that the endpoint is summarized as a mean with a standard deviation and measured within 1 month from the screening visit. In general, a mean gives the average observed value, while the standard deviation describes the spread of individual values around that average. These quantities do not, by themselves, show how precisely a difference between groups has been estimated.

HOMA-IR is used in this study as an index relevant to insulin sensitivity. It is not a direct measure of every aspect of glucose regulation, and its interpretation depends on the recorded glucose and insulin measurements and the stated calculation. The registry describes a minimum number required to find a significant difference between groups considering intra-subject variation, but it does not report the assumptions behind that planning statement or the resulting group estimates. The posted record does not include HOMA-IR means, standard deviations, a between-group estimate, or a confidence interval.

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 and standard deviation. These are descriptive statistics: the mean represents the arithmetic average of measured values, and the standard deviation indicates how dispersed those measurements are around the mean. General statistical interpretation distinguishes this within-group spread from the uncertainty in a comparison between groups. A standard deviation is not itself a confidence interval for the group contrast.

For a comparison of means, the estimated difference describes the contrast between group averages. A confidence interval communicates the uncertainty associated with that estimate under the method used. A p-value, when reported, addresses compatibility between the observed data and a specified null model; it does not measure the size or clinical importance of a difference. The registry record does not report an estimated contrast, confidence interval, or p-value for HOMA-IR. Accordingly, no conclusion about the precision or statistical evidence for a difference can be drawn from the posted outcome information.

The endpoint calculation is stated as HOMA-IR = (Glucose * Insulin) / 22.5, with glucose measured in mmol/L and insulin in milli-units per liter. The record says that higher values indicate lower insulin sensitivity. This is an index derived from two measurements, rather than a direct readout of every physiological process relevant to insulin action. Interpretation should therefore retain its specified meaning and not extend beyond the measurement described.

The study also describes a meal tolerance test, hyperglycemic clamp, and arginine test. In general, a meal-based assessment can collect hormone responses in relation to a meal, while a clamp and a stimulation test can characterize aspects of glucose regulation and beta-cell response under test conditions. The record states that these procedures were intended to assess incretin hormones, beta-cell function, and acute insulin response. It does not report the detailed test procedures, timing of samples, assay methods, or analysis methods for these measurements.

GLP-1 AUC is a secondary outcome. In general, an area under the curve represents an accumulated response across a specified measurement interval. Its interpretation depends on how the interval and curve are defined and how measurements are handled. Those details are not reported in the registry record. Serum DPP-IV concentration is another listed secondary outcome; the record does not report its group estimates or the methods used to analyze it. The study description also mentions DPP-IV activity, but the listed secondary outcome is serum DPP-IV concentration, so activity results cannot be assumed.

The groups are defined by age, and the registry explicitly says that this is not a randomized comparison. In general, random assignment can help make groups comparable with respect to both measured and unmeasured characteristics. Without randomization, observed group contrasts may also reflect differences in participant characteristics or other factors. The record does not state an allocation process, and it cautions that the groups are not like-for-like controls. It does not report adjusted estimates or identify a set of covariates used for adjustment.

The primary endpoint description refers to a minimum number required to find a significant difference between groups while considering intra-subject variation. This is a planning statement, not an outcome result. Detailed assumptions, a target effect, and a sample-size justification are not reported in the registry record. Any planning illustration based on an observed effect is distinct from the trial's original design justification. Such an illustration is not observed power and does not establish what the study was designed to detect.

General statistical planning for a mean comparison depends on assumptions about the effect to detect, variability, allocation, significance level, and analysis method. The registry record does not give the study's own complete planning assumptions or a full statistical analysis plan. It also does not report whether interim analyses occurred. No conclusions about those procedures should be inferred from the stated endpoint or enrollment.

Multiplicity concerns arise when several outcomes or several analyses are tested. In general, conducting multiple tests can increase the chance of at least one nominally unusual result unless the analysis plan addresses that issue. The registry lists a primary outcome and secondary outcomes, and it reports six outcome measures and six analyses in the record. However, it does not state whether multiplicity adjustments were planned or applied, how the six analyses relate to outcomes, or which tests were designated confirmatory. No multiplicity-adjusted result is reported.

Missing-data methods affect how incomplete measurements contribute to an analysis. General approaches may use complete observations, imputation, or model-based methods, but the appropriate approach depends on why data are missing and on the analysis plan. Missing-data procedures, analysis populations, and outcome-specific denominators are not reported in the registry record. The enrollment figure alone does not establish that every enrolled participant contributed data to every endpoint.

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("Elderly Normal Glucose Tolerance (NGT)", "Middle-age Normal Glucose Tolerance (NGT)")
n   <- c(12, 12)
m   <- c(1.91, 0.84)
sp  <- c(1, 0.21)
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  Elderly Normal Glucose Tolerance (NGT)  12  1.910  1.000  1.275  2.545
CARM  Middle-age Normal Glucose Tolerance (NGT)  12  0.840  0.210  0.707  0.973

11. Multiplicity, Missing Data and Analysis Populations

The registry lists a primary outcome, HOMA-IR, and secondary outcomes that include serum DPP-IV concentration and GLP-1 AUC. It also records six outcome measures and six analyses. These entries establish that more than one outcome or analysis is part of the record, but they do not explain how the analyses were organized or which results were considered confirmatory.

In general, multiplicity matters when several statistical tests are conducted because the probability of obtaining at least one apparently notable result can rise across a family of tests. A prespecified testing hierarchy or adjustment can address that issue, but the registry record does not report whether any such approach was planned or used. It also does not report adjusted p-values or identify a family of hypotheses.

Missing-data handling is not described. The record does not state how incomplete HOMA-IR measurements, hormone measurements, or other assessments were handled, nor does it provide endpoint-specific analysis denominators. The enrollment of 24 does not show how many participants contributed to each analysis.

Analysis populations are also not defined in the registry record. No intention-to-treat or per-protocol population is described, and the study is not presented as a randomized treatment trial. The statistical analysis plan, covariate adjustment procedures, interim analyses, and handling of protocol deviations are not reported in the registry record. These omissions limit reconstruction of how the investigators intended to move from measurements to reported estimates.

12. 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.

The registry reports zero serious adverse events among 12 participants at risk in the elderly NGT group and zero among 12 at risk in the middle-age NGT group. It also reports zero other adverse events among 12 participants at risk in each group. The serious-event listings contain no terms, and the registry gives no death count for either group.

These figures should be read as the entries recorded for the listed groups and categories, not as a complete account of safety monitoring. The registry record does not describe how adverse events were defined, how they were collected, or the period covered by the safety fields. Because the death fields are not reported, a death total cannot be inferred from the zero event entries.

In general, a zero count means no events were recorded in that category for the participants represented in the field; it does not establish that an event is impossible. These safety entries also do not address the primary physiological outcomes or indicate whether the groups differed in HOMA-IR, incretin measures, or other assessments.

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

The study addresses a physiological question: whether measures related to insulin sensitivity and the entero-insular axis differ between elderly and middle-age normoglycemic groups. The registry describes HOMA-IR as the primary endpoint and lists assessments of incretin hormones, beta-cell function, acute insulin response, body composition, and basic biochemistry. It identifies GLP-1 AUC and serum DPP-IV concentration among the secondary outcomes.

The record does not report numerical outcome results. There is therefore no basis in the posted information to state which group had higher or lower HOMA-IR, whether a difference was statistically distinguishable from no difference, or how precise an estimate might be. The same limitation applies to the listed secondary outcomes and physiological assessments. The study's completed status is not itself evidence about the direction or magnitude of any result.

The comparison is between age-defined groups and is not randomized. The registry says allocation is not stated and cautions that the arms are not like-for-like controls. Any observed difference, if reported elsewhere, would describe these groups under the study's measurement conditions; the registry information alone would not establish that age caused the difference. Adjustment for other factors and the analysis population are not reported in the registry record.

More broadly, results from a physiological comparison in normoglycemic volunteers would answer a different question from a randomized evaluation of treatment. The study description discusses the potential relevance of incretin physiology to elderly-onset type 2 diabetes, but the record does not describe a therapeutic intervention or report treatment outcomes. It therefore cannot establish an effect of an incretin-based treatment. Its stated focus is characterization, and the available record lacks the outcome estimates needed to assess even the group contrasts directly.

The safety fields record zero serious and zero other adverse events in each group, with 12 participants at risk per group; death counts are not reported. These entries should be interpreted narrowly, alongside the absence of further safety-method details. Overall, the registry outlines the question and measurements but does not provide the results required to judge the magnitude, uncertainty, or broader implications of the physiological comparisons.

14. Why This Trial Matters Statistically

This study is statistically interesting because it frames a biological question through several kinds of measurements rather than through a treatment-versus-control contrast. HOMA-IR is the primary continuous endpoint, while the description also includes meal-related incretin measurements, a clamp, an arginine test, and assessments of body composition and basic biochemistry. Such a design raises questions about how different measures relate and how a primary result should be distinguished from secondary or exploratory findings.

The age-defined groups also make the comparison vulnerable to interpretive limits that are different from those in a randomized trial. The registry says the comparison is not randomized, allocation is not stated, and the arms are not like-for-like controls. Statistical adjustment can sometimes address measured differences, but the record does not report whether adjustment was used or which factors were considered. A group contrast should therefore not be read automatically as an isolated effect of aging.

Multiple outcomes and analyses make transparent reporting important. The registry lists six outcome measures and six analyses, but it does not explain the analysis hierarchy, multiplicity handling, missing-data methods, or analysis populations. Those details affect how readers interpret the reliability and scope of any reported results. In this record, the numerical outcome estimates are not reported, so the statistical value lies in identifying both the intended measurements and the information needed for a complete assessment.

The record also illustrates why enrollment and completion status are not substitutes for results. Knowing that 24 participants were enrolled and that the study is completed does not reveal endpoint distributions, group contrasts, or their precision. A transparent statistical account would need to connect the measurement procedures to estimates and uncertainty while clearly distinguishing descriptive findings from causal conclusions.

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 key limitation for interpreting the findings is that numerical outcome results are not reported in the registry record. Group-specific HOMA-IR means and standard deviations, contrasts, confidence intervals, and p-values are absent from the registry entries. The same is true for the secondary outcomes and the other described physiological assessments. The magnitude and precision of the intended comparisons therefore cannot be evaluated.

The registry describes an age-group comparison that is not randomized, with allocation not stated, and says the arms are not like-for-like controls. The record does not provide enough information to assess baseline comparability or to determine whether analyses adjusted for other characteristics. This limits causal interpretation of any potential group differences.

The stated enrollment is 24, but participant flow and endpoint-specific denominators are not reported. Eligibility criteria beyond the group descriptions, recruitment details, missing-data procedures, and analysis populations are also not reported in the registry record. It is not possible to determine from enrollment alone whether all participants completed every assessment.

Additional methodological details are absent, including assay procedures, precise definitions and timing for secondary outcomes, the statistical analysis plan, multiplicity procedures, and any interim analyses. The registry's sample-size wording does not provide the complete assumptions or a detailed justification. Safety information is similarly limited: event counts are listed, but event definitions, observation periods, collection methods, and death counts are not reported.

Finally, the study description concerns normoglycemic volunteers and physiological characterization, not a therapeutic comparison. The registry's discussion of possible relevance to elderly-onset type 2 diabetes does not make the study a treatment-efficacy evaluation. These limits should guide interpretation of the scope and completeness of the record.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: The Aging Endocrine Pancreas: Characterization of the Entero-insular Axis Physiology in the Elderly — NCT00843479.
• Registry record last updated 2013-04-22; status last verified 2013-03.
• Results first posted 2013-04-22.
• 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

The registry describes a completed study sponsored by the University of Campinas, Brazil, with enrollment of 24. Its focus is the entero-insular axis in elderly participants compared with middle-age normoglycemic participants. The listed age ranges are 65-80 years and 35 to 50 years.

The primary outcome is HOMA-IR, summarized as a mean and standard deviation and measured within 1 month from the screening visit. The described assessments include a meal tolerance test, a hyperglycemic clamp followed by an arginine test, body composition, and basic biochemistry. Listed secondary outcomes include serum DPP-IV concentration and GLP-1 AUC.

The registry states that the comparison is not randomized, allocation is not stated, and the arms are not like-for-like controls. It records zero serious and zero other adverse events in each group among 12 participants at risk per group; death counts are not reported. Numerical results, statistical uncertainty, missing-data methods, analysis populations, and multiplicity procedures are not reported in the registry record.