A Study of Non-invasive Measurement of Blood Glucose and Blood Pressure: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for A Study of Non-invasive Measurement of Blood Glucose and Blood Pressure (NCT05904769), a non-randomized na study. The primary outcome is Systolic Blood Pressure.

2. Clinical Question

3. Trial Design

This registry record describes a device study of non-invasive measurement of blood glucose and blood pressure, with an official title that also refers to extrapolation of the QRS complex using a wrist wearable photoplethysmography sensor. The sponsor is Mayo Clinic. The study is listed as phase NA and uses a non-randomized, parallel design with no masking. These features describe how the study was organized; they do not establish that the two groups were intended as interchangeable controls.

The LIFELEAF Smartwatch was the intervention. The record describes a Hospitalized Diabetic Group and an Electrophysiologic (EP) Group. The former was planned to include hospitalized people with diabetes receiving insulin and undergoing blood sugar checks four times daily, wearing the device throughout the hospital stay. The latter was to include people undergoing an EP procedure, wearing the device for the duration of the procedure. The settings and procedures differ, so outcomes from these groups should not be interpreted as a randomized comparison of the device against a control arm.

Enrollment is listed as 87. The status is terminated. The study start date is 2023-05-31, and the primary completion date is 2024-04-30. The primary endpoint description says that zero subjects were enrolled in the hospitalized diabetic arm because the study was terminated early due to a lack of staffing support. The registry record does not report a sample-size justification, details of any protocol amendments, or an explanation of staffing circumstances beyond that statement.

The broader study purpose was to compare smartwatch readings for blood glucose, blood pressure, and ECG with standard methods. The primary outcome listed is systolic blood pressure at baseline, defined as a mean continuous measure and described as a comparison of wrist-based PPG and invasive blood pressure measurements. The registry lists 3 outcome measures and 0 analyses. A numerical result for the primary endpoint is 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: Zero subjects were enrolled in the hospitalized diabetic arm as the study was terminated early due to a lack of staffing support.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Zero subjects were enrolled in the hospitalized diabetic arm as the study was terminated early due to a lack of staffing support.

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: Zero subjects were enrolled in the hospitalized diabetic arm as the study was terminated early due to a lack of staffing support.

6. Primary Endpoint

The registry lists the primary outcome as Systolic Blood Pressure, measured over Baseline.

The primary endpoint is systolic blood pressure, measured in mmHg, at baseline. The registry defines it as the difference between a measurement from the wrist-based photoplethysmography sensor and invasive blood pressure measurement. It is specified as a mean of a continuous measure, with standard deviation identified as the measure of dispersion. The endpoint is intended to describe how the two measurement approaches compare for systolic blood pressure.

In general, comparing a wearable measurement with a reference measurement can assess how closely the device readings correspond to the reference in the study setting. A mean difference describes the average direction and size of measurement differences across observations included in an analysis. A standard deviation describes how much individual observations vary around the mean; it is not, by itself, a measure of uncertainty in the mean or a statement about agreement for every individual reading.

The registry record does not report a numerical mean difference, standard deviation, confidence interval, or analysis population for this endpoint. It states that zero subjects were enrolled in the hospitalized diabetic arm because the study was terminated early due to a lack of staffing support. Without reported endpoint observations and an analysis, the record does not establish the size or precision of any systolic blood pressure difference. The endpoint definition should therefore be distinguished from evidence about the observed performance of the device.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The primary outcome is a continuous measurement: systolic blood pressure in mmHg. A mean is a summary of the central value of a set of observations. The registry’s endpoint description frames the quantity of interest as a difference between the wrist-based PPG measurement and invasive blood pressure measurement. Interpreting such a difference requires a clear definition of which measurement is subtracted from which, and a set of paired or otherwise appropriately matched observations. The registry record does not state the subtraction order or describe the measurement pairing procedure beyond naming the two methods.

What does the mean difference represent?

In general, a mean difference summarizes the average discrepancy between two measurement methods in the analyzed observations. Its sign depends on the order of subtraction, so a positive or negative value has meaning only when that order is clear. Its size describes an average and does not imply that every individual pair of readings has the same discrepancy. A mean alone can also conceal variation across observations, which is why the registry identifies standard deviation as a dispersion measure.

Standard deviation describes the spread of observations around their mean. It is different from a standard error, which describes the estimated uncertainty of a statistic, and from a confidence interval, which presents a range of values compatible with the data and a specified method. The record specifies standard deviation as the dispersion measure but does not report its value. It also does not report a standard error or confidence interval for the endpoint. Therefore, neither the observed variability nor the precision of an estimated mean difference can be evaluated.

What can a confidence interval add?

In general, a confidence interval helps readers distinguish the estimated effect from its uncertainty. It should be interpreted in the context of the analysis method, the amount and structure of available data, and the assumptions underlying that method. An interval is not a guarantee that the true value lies within its limits, and it does not by itself establish practical importance. No primary endpoint confidence interval is reported in the registry record, so those interpretations cannot be made for this study’s primary comparison.

The study is listed as non-randomized, unmasked, and parallel. In general, non-random allocation can leave groups different in ways that affect outcomes, while masking can reduce some forms of measurement or assessment bias. Those design considerations matter when interpreting comparisons. In this record, the two described groups also differ in setting: one involves hospitalization and diabetes, while the other involves an EP procedure. The registry cautions that the arms are not a like-for-like control comparison. The primary endpoint is a measurement comparison, not a randomized treatment contrast.

How should the planning assumptions be read?

The record describes a planning illustration based on the observed effect, with a two-sided significance level of 0.05, equal allocation between arms, and a normal approximation. It states that the effect to detect is a stated fraction of the observed effect. These are assumptions for planning illustrations, not a report of the trial’s design justification or observed statistical power. The registry record does not report the trial’s own sample-size justification. It also does not report numerical planning outputs in the information available for this analysis.

In general, a planning calculation estimates the amount of information that might be needed under specified assumptions. Its result depends on the assumed effect, variability, allocation, and statistical method. A calculation based on an observed effect can be especially uncertain when the underlying estimate is imprecise or not reported. It should not be described as observed power, and it cannot repair the absence of a reported endpoint analysis.

Over-dispersion is a general concern when observed variability is greater than a model assumes. For a continuous endpoint, an incorrect variance assumption can make uncertainty estimates unreliable. The record does not report an analysis model or sufficient endpoint statistics to assess this issue. No claim about the use of a particular model, adjustment, or variance correction can be made from the registry information.

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("Electrophysiologic (EP) Group")
n   <- c(81)
m   <- c(13.08)
sp  <- c(17.22)
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  Electrophysiologic (EP) Group  81  13.080  17.220  9.272  16.888

11. Multiplicity, Missing Data and Analysis Populations

The registry lists 3 outcome measures and 0 analyses. It names systolic blood pressure at baseline as the primary outcome, but the information reported does not provide numerical results for that endpoint. The registry record does not describe how the other outcome measures were analyzed or how their results relate to the primary question.

Multiplicity is a general statistical issue that arises when several outcomes, comparisons, time points, or analyses are considered. Examining many results can increase the chance of observing an apparently notable finding by chance. Researchers may address this through a prespecified hierarchy, adjustment method, or a clear distinction between confirmatory and exploratory analyses. The registry record does not report a multiplicity strategy, and no adjustment should be inferred.

Missing-data methods are also not reported in the registry record. The statement that zero subjects were enrolled in the hospitalized diabetic arm is a report about the primary endpoint population, not a description of individual missing measurements or a missing-data procedure. The record does not explain whether any measurements were incomplete in the EP group, how unusable readings were handled, or whether any imputation or sensitivity analysis was performed.

The analysis populations are not reported in the registry record. It does not specify which enrolled participants contributed to each endpoint, what inclusion criteria were applied to measurements, or how repeated measurements, if any, were handled. Without those details and an endpoint analysis, the extent to which the reported enrollment contributes to the primary comparison cannot be determined.

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 adverse-event information lists the Hospitalized Diabetic Group with 0 at risk for serious adverse events and 0 affected, and 0 at risk for other adverse events and 0 affected. The EP Group is listed with 87 at risk for serious adverse events and 0 affected, and 87 at risk for other adverse events and 0 affected. Deaths are listed as 0 for each group. No serious adverse-event terms are listed.

These figures describe the entries in the registry; they should not be read as proof that no adverse events could occur or that the device is safe in other populations or settings. The hospitalized diabetic group has no participants at risk in the adverse-event record, consistent with the primary endpoint description that zero subjects were enrolled in that arm. A zero affected count in a group with participants at risk means no affected participants are recorded in that registry entry; it does not establish that risk is absent.

The record does not provide event narratives, severity details beyond the serious/other distinction, follow-up duration for safety, or an explanation of how adverse events were collected. These counts therefore have limited scope and should be interpreted alongside the study’s early termination and the absence of reported primary endpoint results.

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

The record establishes that the study was intended to examine readings from the LIFELEAF Smartwatch against standard measurement methods, with a primary focus on systolic blood pressure measured by wrist-based PPG versus invasive measurement. It also describes a broader interest in blood glucose, blood pressure, and ECG readings. The primary endpoint was defined as a mean continuous measure at baseline, with standard deviation named as the dispersion measure.

That description is not a finding about measurement accuracy or agreement. The registry record does not report the numerical primary endpoint result, the variability of the observations, or an interval showing the estimate’s precision. It therefore does not support a conclusion about the size or direction of the difference between methods. Nor does the lack of a reported estimate show that there was no difference.

The endpoint population is especially important: the record states that zero subjects were enrolled in the hospitalized diabetic arm because the study was terminated early due to a lack of staffing support. The presence of enrollment of 87 in the record and adverse-event entries for the EP Group does not provide the missing primary comparison for the hospitalized diabetic population. The two groups were not randomized and are not described as a like-for-like control comparison.

In general, evidence about a measurement device depends not only on an average difference but also on the spread of individual differences, the methods used to collect and pair readings, and the precision of the estimates. Those details and results are not reported in the registry record. The posted information can therefore be used to understand the study’s aims, design, endpoint definition, and reported safety counts, but it does not establish how the device performed on the primary endpoint.

14. Why This Trial Matters Statistically

This study illustrates why an endpoint definition and an endpoint result are not the same thing. A registry can specify a meaningful measurement comparison—in this case, systolic blood pressure from a wrist-based PPG sensor versus invasive measurement—without reporting the numerical estimate needed to judge the observed difference or its precision. For statistical interpretation, the distinction is fundamental: a planned question describes what investigators intended to learn, while analyzed observations are needed to answer it.

The record also highlights the importance of the target population. The primary endpoint description states that zero subjects were enrolled in the hospitalized diabetic arm because of early termination related to staffing support. That limitation prevents the registry from presenting an estimate for the stated population. Enrollment reported elsewhere in the record does not automatically resolve this gap, particularly because the EP group represents a different setting and the allocation is non-randomized.

For researchers, this case underscores the value of clearly reporting analysis populations, measurement procedures, estimates, variability, uncertainty, and the handling of missing or unusable readings. Those details let readers distinguish device performance from the limits imposed by study conduct and data availability. The record lists 3 outcome measures but 0 analyses, making transparent outcome reporting especially important for understanding what evidence was obtained.

The statistical lesson is not a conclusion about whether the wearable is useful. It is that design descriptions, planned endpoints, safety counts, and quantitative comparative results answer different questions. Keeping those categories separate helps avoid treating an incomplete record as evidence of equivalence, benefit, harm, or measurement accuracy.

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 main limitation is that the registry record does not report a numerical result for the primary systolic blood pressure endpoint. It supplies no mean difference, standard deviation value, confidence interval, or analysis. The endpoint’s precision and direction therefore cannot be assessed.

The endpoint description states that zero subjects were enrolled in the hospitalized diabetic arm because the study was terminated early due to a lack of staffing support. This leaves the population named in the primary endpoint without enrolled participants, as described in the record. Enrollment is listed as 87, but the record does not provide a primary endpoint analysis that would clarify which observations contributed to the intended comparison.

The design is non-randomized, unmasked, and parallel. The record cautions that the arms are not a like-for-like control comparison. The groups also differ by setting and procedure, so results from one should not be assumed to represent the other. The registry does not report the detailed measurement protocol, how paired readings were obtained, or the analysis population for each outcome.

Further limitations are that missing-data procedures, multiplicity handling, and the statistical analysis plan are not reported in the registry record. Although 3 outcome measures are listed, the record lists 0 analyses. The adverse-event entries provide counts but no event narratives or follow-up details. The record also does not report a sample-size justification or further detail about the staffing issue. These omissions restrict interpretation of both the intended comparison and the information available from the study.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: A Study of Non-invasive Measurement of Blood Glucose and Blood Pressure — NCT05904769.
• Registry record last updated 2025-10-08; status last verified 2025-09.
• Results first posted 2025-10-08.
• 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 record describes NCT05904769, a Mayo Clinic device study of the LIFELEAF Smartwatch for non-invasive measurement of blood glucose and blood pressure, with the official title also referring to QRS-complex extrapolation. It is listed as phase NA, non-randomized, unmasked, and parallel. Enrollment is 87; the status is terminated. The study start date is 2023-05-31, and the primary completion date is 2024-04-30.

The primary endpoint is baseline systolic blood pressure, defined as a mean continuous measure comparing wrist-based PPG with invasive measurement. The record states that zero subjects were enrolled in the hospitalized diabetic arm because of early termination related to staffing support. It lists 3 outcome measures and 0 analyses. No numerical primary endpoint result is reported in the registry record.