Accuracy of Abott Freestyle Libre versus Dexcom G6 in a patient with pre-diabetes: a case report and review of literature

doi:10.21203/rs.3.rs-3893915/v2

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Case Report

Accuracy of Abott Freestyle Libre versus Dexcom G6 in a patient with pre-diabetes: a case report and review of literature

https://doi.org/10.21203/rs.3.rs-3893915/v2

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Abbott FreeStyle Libre and Dexcom G6 represent widely employed continuous glucose monitoring (CGM) systems globally. However, their precision remains unexplored concerning postprandial glucose levels in individuals with pre-diabetes following the consumption of diverse dietary regimens.

A 58-year-old Japanese man diagnosed with pre-diabetes (postprandial hyperglycemia) underwent simultaneous monitoring using Abbott FreeStyle Libre and Dexcom G6 following the consumption of diverse diets. In the pre-meal state, both systems exhibited comparable and reliable values (around 80-100 mg/dl). However, around 60 minutes following meals containing specific amounts of carbohydrates (approximately above 50 g), FreeStyle Libre demonstrated a more pronounced acceleration in the increase and peak glucose values compared to G6. These discrepancies were further validated through self-monitoring of blood glucose (SMBG) measurements, confirming the less accurate performance of FreeStyle Libre under these conditions. To this end, it appears that fermented products (beans, yogurt, cheese) could suppress postprandial glucose spikes.

The study results suggest that, when compared to G6, FreeStyle Libre yielded elevated glucose values and exhibited reduced accuracy in measuring postprandial glucose levels following the ingestion of a specific amount of carbohydrates in a patient with pre-diabetes.

pre-diabetes

postprandial hyperglycemia

CGM

FreeStyle Libre

Continuous Glucose Monitoring (CGM) is an invaluable device for the ongoing assessment of interstitial fluid glucose levels, particularly for individuals undergoing insulin injections. Various CGM systems, utilizing diverse technologies, are currently available or in developmental stages. Comparative studies with self-monitoring blood glucose (SMBG) demonstrate that CGM not only reduces HbA1c but also diminishes the duration and frequency of hypoglycemic events (1). Presently, two widely utilized systems, Abbott FreeStyle Libre (Abbott, Chicago, USA) and Dexcom G6 (Dexcom, San Diego, USA), have gained prominence worldwide. Notably, these systems eliminate the need for calibration with SMBG (2).

A distinguishing feature of FreeStyle Libre, classified as a flash glucose monitoring (FGM) or intermittently scanned continuous glucose monitoring (isCGM) system, is its ability to continuously measure interstitial fluid glucose levels within the sensor at 15-minute intervals for up to 8 hours. Unlike many other CGM systems, including G6, FreeStyle Libre stores all data internally in the sensor (2). While the original FreeStyle Libre has been discontinued in some countries, it remains available in others, such as Japan. The newer versions, FreeStyle Libre 2 or 3, are recommended, offering enhancements like alarms for high or low glucose levels and more frequent glucose measurements (every 1 minute). Despite these updates, the fundamental technology remains consistent (3). Several comparative reports evaluating glucose trends between FreeStyle Libre (original and versions 2) and other CGMs, including G6, in various specific circumstances suggest that FreeStyle Libre is less accurate under certain conditions (2, 4, 5, 6).

To date, there has been no comprehensive investigation involving the simultaneous use and comparison of two different CGM systems in an individual with pre-diabetes subjected to diverse dietary conditions. Prediabetes is characterized by blood glucose levels exceeding the normal range but not reaching the threshold for a diagnosis of type 2 diabetes (T2DM). The initial anomaly in glucose metabolism often manifests as an elevation in postprandial glucose levels due to diminished first-phase insulin secretion. Over time, a progressive decline in beta-cell function contributes to an increase in fasting glucose levels (7, 8). Patients with pre-diabetes frequently present as asymptomatic and may not undergo routine examinations. Halting the progression to overt T2DM necessitates the identification of populations at risk for prediabetes, coupled with encouragement for lifestyle modifications, including dietary changes and regular exercise. In such instances, CGM emerges as a highly beneficial method for continuous monitoring of blood glucose levels.

In this study, CGM data were collected from a single patient diagnosed with prediabetes, characterized by elevated postprandial glucose levels alongside normal fasting blood glucose (FBG) and HbA1c. The participant concurrently wore both FreeStyle Libre and Dexcom G6 systems, allowing for the simultaneous measurement of glucose levels. The investigation involved monitoring glucose responses following the consumption of various traditional and modern Japanese diets.

The patient under scrutiny in this report is a 58-year-old male who has exhibited elevated postprandial glucose levels for the past decade. Despite maintaining normal fasting blood glucose and HbA1c levels (ranging from 87-102 mg/dl and 5.4-5.8%, respectively), his post-meal glucose levels vary (ranging from 130-184 mg/dl) depending on dietary choices. One healthcare professional diagnosed him with "pre-diabetes." The patient does not have any other clinically significant disorders and is not currently on any medication. His physical attributes include a height of 179 cm and a weight of 75 kg.

To monitor blood glucose levels, the patient had been utilizing FreeStyle Libre and SMBG devices, such as Medisafe Fit Kit (Termo, Tokyo, Japan) or OneTouch Ultra Vue (LifeScan Japan, Tokyo, Japan). However, discrepancies in the data, particularly after meals, have been observed between these devices. To assess the accuracy and reliability of FreeStyle Libre data, the patient opted to simultaneously wear FreeStyle Libre (on the left upper arm) and G6 (on the right lower abdomen). This dual monitoring approach was employed to compare the data gathered after consuming various daily traditional and modern Japanese diets. As a control measure, intermittent SMBG tests were conducted to validate the data acquired from these two distinct CGMs.

The FreeStyle Libre CGM has a lifespan of 14 days, whereas the Dexcom G6 CGM is designed for a duration of 10 days. It is empirically recognized within the medical community that the data recorded at the commencement and conclusion of these monitoring periods tends to be less stable. Consequently, in this report, data from day 2 through day 9 following initiation were selectively analyzed. Throughout this period, the individual maintained a calm state and refrained from engaging in excessive physical exercise after meals.

The following the details of the CGM apparatus and data.

G6 receiver info: SN PG13705811

Transmitter SN 8PE5MM

PN 9500-91

LOT 5324787

FreeStyle Libre reader SN JCGX052-T0265

Libre sensor 0m000UJLL AO

To validate the aforementioned results, a second trial using new sensors and similar diets was conducted, yielding nearly identical outcomes (results not shown).

Postprandial hyperglycemia not only elevates the relative risk for developing type 2 diabetes (T2DM) but also heightens the likelihood of cardiovascular complications, such as angina, myocardial infarction, or strokes (7, 8). The mechanism by which postprandial hyperglycemia contributes to cardiovascular issues involves vascular oxidative stress, endothelial dysfunction, and an inflammatory response (7). Consequently, it becomes crucial to identify individuals with elevated postprandial glucose levels and implement appropriate interventions. The primary objective of this study was to evaluate the accuracy of the two most widely used CGMs, Abbott FreeStyle Libre and Dexcom G6, in an individual with pre-diabetes characterized by postprandial hyperglycemia. This investigation was prompted by the subject's suspicion regarding the accuracy of FreeStyle Libre, stemming from observed disparities in glucose values compared to SMBG.

This report demonstrates that, following the consumption of carbohydrate-rich diets (typically exceeding 40-50g), FreeStyle Libre consistently yielded higher and inaccurate glucose levels compared to reference SMBG data, while G6 provided more reliable glucose values (Figures 1, 4, 5). Conversely, pre-meal glucose levels exhibited comparability and accuracy in both devices (Figures 1, 2, 3, 4, 5). It is imperative for FreeStyle Libre users to exercise caution and validate glucose values with SMBG, particularly in instances involving insulin injection. Furthermore, the applicability of these findings in patients with overt diabetes remains an open question and warrants exploration under various circumstances such as surgical operations, hemodialysis, exercise, or periods of relaxation. Further investigation is needed to ascertain whether similar results would be observed in these diverse scenarios.

While the accuracy of FreeStyle Libre, including both the original version and the newer version 2, remains a subject of debate among researchers, particularly when assessed by the Mean Absolute Relative Difference (MARD) (2, 4, 5, 6), its cost-effectiveness and certain favorable features make it a valuable tool in various scenarios. For instance, it can be particularly useful for comparing the impact of different diets on blood glucose levels, such as comparing the effects of bananas versus oranges or pizza versus pasta. Additionally, it can aid in assessing the peak time after consuming diverse meals.

Traditionally, postprandial glucose evaluation is empirically conducted at 2 hours after a meal. However, emerging research suggests that the peak postprandial glucose occurs around 60 minutes after eating (9, 10). This time frame (around 60 minutes after meal) might serve as a more relevant predictor for the development of overt diabetes or cardiovascular disorders compared to the 2-hour mark. In the findings presented in this report, the peak glucose levels after meal ingestion were also approximately 60 minutes after ingestion (Figures 1, 3, 4, 5). CGMs may be valuable in comparing the time taken to reach peak glucose levels based on the diet consumed (pasta vs. rice vs. bread). This information can be crucial in determining the optimal timing for post-meal exercise.

Yogurt and cheese together with chocolate exhibited minimal glucose spikes in both devices though certain carbohydrates were ingested (Tables 3). This aligns with prior research indicating that dairy products can mitigate glucose excursions after a meal (11). Tofu and natto, both common Japanese foods derived from fermented soybeans, have been associated with potential protective effects against type 2 diabetes (T2DM) and the suppression of post-meal glucose spikes (12). In this study, little glucose spikes, if any, were noted with the consumption of tofu and natto (Figure 2). Notably, low-carbohydrate diets are recognized as an effective strategy for controlling post-meal glucose elevation. However, one common challenge with such diets is the potential dissatisfaction of satiety. Remarkably, certain diets utilized in this study, such as tofu, natto, yogurt, cheese, and chocolate, not only exhibited minimal glucose spikes (results not shown as Figure or Table) but also provided a satisfactory level of satiety.

In order to corroborate the findings of this study, it is imperative to conduct randomized, controlled dietary intervention trials encompassing diverse diets and a sufficiently large number of subjects. Such trials would shed light on the role of postprandial glycemia. Equally important is the exploration of the time course of postprandial glycemia to gain a comprehensive understanding of its potential impact.

FreeStyle Libre consistently yielded higher and inaccurate postprandial glucose values, while Dexcom G6 demonstrated greater reliability following the ingestion of specific carbohydrate amounts in a person with pre-diabetes. Despite these discrepancies, FreeStyle Libre remains a useful tool for tracking trends in glucose changes. However, for added safety and result verification, occasional confirmation with Self-Monitoring of Blood Glucose (SMBG) is recommended.

Ethical considerations

Informed consent was obtained from the patient for the publication of the present case report.

Declaration of interest

No potential conflict of interest was reported by the author.

Data availability statement

The data generated and analyzed in the presented study are available from the corresponding author on request.

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The authors declare no competing interests.

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Accuracy of Abott Freestyle Libre versus Dexcom G6 in a patient with pre-diabetes: a case report and review of literature

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Version 2

Abstract

Figures

Introduction

Case Presentation

Discussions

Conclusion and recommendation

Declarations

Ethical considerations

Declaration of interest

Data availability statement

References

Additional Declarations

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