The Influence of Digital Affinity on the Continuous Glucose Monitoring System Choice by People With Type 1 Diabetes

Abstract

Background:

Since several years, continuous glucose monitoring (CGM) systems became a standard of care in patients with intensified conventional treatment (ICT) in many countries. CGM results in an ongoing record of digital information that provides an added value to patients with type 1 diabetes (T1D) and healthcare providers, among others. This implies the patient’s acceptance of data analyses and storage and an adjustment on self-management. The aim of the study was to investigate the influence of digital affinity on the CGM use and the choice of a particular system.

Methods:

In a quantitative survey 2102 patients with T1D were interviewed via an online questionnaire. The study is based on the technology acceptance model (TAM). Self-assessment of digital affinity was correlated with various features of CGM use and preferences. Significance of associations and correlations was tested.

Results:

Digital affinity correlated positively with CGM use for the self-management with ICT. Significant differences were found regarding the use of a particular system suggesting a correlation between digital affinity and the complexity of CGM data portrayal and interconnectivity with smart devices (eg, smartwatches).

Conclusions:

While suppliers of CGM systems focus on progress regarding the ease of use of their systems, they also provide a developing interconnectivity with smart devices and cloud-based data storage. This requires a higher digital affinity among users. While factors such as recommendations by physicians and coverage by health insurance companies have an impact on the system choice, the data demonstrate a correlation between digital affinity and particular CGM systems.

Introduction

Since the reimbursement decision of the German Federal Joint Committee (G-BA) in 2016, every insulin-dependent patient with diabetes and intensified conventional treatment (ICT) qualifies for a real-time continuous glucose monitoring (rtCGM) system. ¹ As a result, there has been an enormous increase in the use of such systems in Germany. ²

However, the main acceptance factors for patients with type 1 diabetes (T1D) who want to use a CGM system have not yet been investigated or cannot be derived from scientific data. Especially for manufacturers of medical devices, these ones would be important to know because future CGM systems may be either build simpler or even more complex.

The reported study is based on the technology acceptance model (TAM) by Davis ³ and Davis et al. ⁴ Thereby various acceptance factors emerged that (may) lead to the desire to wear a CGM system. These factors include perceived ease of use, perceived usefulness, monitoring fears, product/technology (use of social media and cloud storage services), fit to the person, aesthetics, design, social environment, physical influencing factors (strain), personality traits, and intention to use. The topic of this paper is specifically about digitization, in detail it addresses the aspect of “digital affinity.” The term “digital affinity” is not clearly defined in the literature. Herzing and Blom ⁵ speak of a “multidimensional classification of digital affinity.” Generally, digital affinity means the willingness to digitize or the pleasure in using the associated interest in new digital technologies ⁶ or rather the use of digital devices and digital efficacy. ⁷ Digital devices include smartphones, laptops, tablets, smart devices (smartwatches and smart wristbands), and virtual assistance devices. Digital affinity is measured by activities, that means the devices which people own and how confident they are when they utilize new technologies. ⁷ In this manner, digital affinity is based on several aspects: digital access divide, digital device divide, digital usage divide, and attitudes toward technological innovation. ⁵ A divide exists between the “use” and “non-use” of digital technologies which leads to a digital divide in society ⁸ —here: persons with T1D, in detail the CGM system users of FreeStyle Libre (FSL) 2 and Dexcom G6 (market access of both: 2018) which were the two most preferred systems at the time of the study in 2020. ⁹

The decision for one of the two systems with the highest market shares might be based on differences regarding their functions. First of all, the fundamental difference between the two systems is that the FSL 2 is an intermittent scanning continuous glucose monitoring (iscCGM) system (also called Flash Glucose Monitoring [FGM] system) compared with the Dexcom G6 (rtCGM) system. While the Dexcom G6 automatically and continuously determines a tissue glucose value every 5 minutes and transmits it to a receiver device, the FSL 2 requires scanning of the sensor with a reading device.^10,11 The approved official wear site, in addition to the back of the upper arm (FSL 2), is the abdomen and upper buttocks on the Dexcom G6. The FSL 2 is age-approved from 4 years, and the Dexcom G6 is age-approved from 2 years. In terms of wearing time, the systems differ by 4 days (FSL 2: 14 days; Dexcom G6: 10 days). Both systems do not need to be calibrated.^11,12

Relating to the digitization aspect, both systems have a customizable alarm function that alerts the patient in case of hyper- and hypoglycemia and a sharing function, whereby, for example, glucose values can be shared with multiple people. In addition, there is compatibility with various smart devices, so that the data can be transferred to a smartphone with the FSL 2 and even to a smartwatch with the Dexcom G5 Mobile or G6.^11,12

However, there are differences between the two CGM systems when evaluating glucose data. To get a better overview of the two systems (Dexcom G6, FSL 2), the technical-functional differences are subdivided into the areas “reader,” “app functions,” and “desktop/cloud software solution.”

With regard to the first area “reader,” the basic difference between the two reporting systems is that the FSL 2 requires the reader (or the smartphone) for scanning glucose values. The patient can only see the determined glucose value including the trend arrow on the reader without gaining insight into the past glucose history of the last 24 hours as with the Dexcom G6.^11,12 In contrast to the FSL 2, the glucose values of the Dexcom G6 are automatically and continuously transferred to the reader (alternatively: smartphone or smartwatch) every 5 minutes. ¹¹

Second point of data evaluation of the glucose values is the area “app functions.” Both CGM systems (Dexcom G6, FSL 2) with their app “Dexcom G6 App” and “FreeStyle Libre Link app” have the features of trend arrow, alarm limits, add notes, current glucose value and glucose history but the Dexcom G6 is more detailed when it comes to the individually adjustable alarm functions.^11,12 For example, the night can be limited to an individual time window, in which glucose values may not exceed or fall below the target corridor. A predictive alarm function is also possible with the Dexcom G6. The patient is warned 20 minutes in advance if severe hypoglycemia (< 55 mg/dl) is imminent (called: urgent low soon). Countermeasures can still be taken in time with the help of time advance. ¹¹

The difference of the detailed glucose value representation becomes particularly clear with the third aspect “desktop/cloud software solution.” The FSL 2 requires the reader to be connected to the computer or the smartphone with the FSL Link app to upload the data. With the Dexcom G6, on the other hand, data exchange can take place automatically once the physician has given permission.^13,14 Regarding the evaluation of glucose data, the Dexcom G6 uses a cloud-based reporting system called “Dexcom CLARITY,” the FSL 2 “LibreView.”^13,14 When using the respective apps, FSL data are uploaded automatically to the cloud and are available in the Libre View environment.

In addition, the full glycemic profile, also called ambulatory glucose profile (AGP), ¹⁵ is mapped in more detail with the Dexcom G6. While only a simplified display of the glucose profile is visible on the FSL 2 scanning device, with the FSL PC software additional evaluation options such as snapshots for the respective specified period, daily course and daily log are given. In comparison, the Dexcom G6 offers a more detailed AGP.^14,15 The data evaluation of the glucose values presents the data in more detail, especially glucose statistics such as pattern and time in range (TIR). ¹³

The decision for one or another CGM system might be made on patient’s preference but in many cases will be influenced by the prescribing physician or even by the health insurance. ¹⁶ Recently, the differences in price led to measures urging physicians to prescribe the systems with the lowest costs.

Of particular interest is the extent to which digital affinity plays a role in the simultaneous use of a CGM system and continuous subcutaneous insulin infusion (CSII) by insulin pump with respect to hybrid closed-loop (HCL) systems. With an HCL system, an approximately closed control loop is established between CGM system and insulin pump. Based on an algorithm, the pump automatically delivers as much insulin as necessary until the glucose value transferred by the transmitter reaches the target value of, for example, 120 mg/dl. This is why it is also referred to as “artificial pancreas.” ¹⁷

At the time of the study, there were 121 000 insulin pumps used by patients with T1D in Germany. With 373 000 persons with T1D this means that around one in three people used a pump, especially individuals with T1D are being provided with a pump when the disease manifests in childhood. The share of CGM systems alone was 117 000 users (T1D); together with FGM systems (175 000), it was 292 000 users (T1D), which corresponds to about 78% of a total of 373 000 patients with T1D in Germany, and thus about three quarters of all patients with T1D use such a system. ¹⁸

The assumption that a young age in combination with a high digital affinity justifies a more complex CGM system will also be investigated in the following. Only recently, Dexcom sensors (high digital affinity) became interoperable with some insulin pumps, enhancing the complexity of the system use. ¹⁹

Methods

To analyze who is using which CGM system, a quantitative survey was conducted over a four-month period in 2020 (July 1-October 31), in which a total of 2102 patients were interviewed via an online questionnaire.

The questionnaire was developed using the TAM by Davis ³ and Davis et al. ⁴ In addition to the acceptance factors already mentioned, such as perceived ease of use, perceived usefulness, and fit to the person, different items were sought for a total of all 11 acceptance factors. For this purpose, the authors Venkatesh and Davis ²⁰ and Brockner ²¹ , among others, were consulted. After the questionnaire with regard to diabetes was set up, the items were first reviewed by 6 experts (2 diabetologists, 2 diabetes consultant, 3 persons with diabetes, 1 employee of the company Dexcom)—whereby diabetologist and employee also having diabetes themselves—for their content and sense.

Before the pretest was carried out by a total of 17 subjects in two diabetology practices, a positive ethics vote was obtained from the Joint Ethics Committee of the University of Bavaria (GEHBa). The feedback of the 17 participants was again included in the questionnaire before the main study started.

Among these, 1642 patients answered the questionnaire completely. Inclusion criteria were an existing T1D, at least 18 years old, and residence in Germany. Participants were recruited by various cooperation partners and via newsletters, e-mails, homepage, information letters to 1000 physician practices throughout Germany and external services of companies and institutions. These included the company Dexcom Deutschland GmbH (Mainz), the Institute for Diabetes Technology (IfDT) of the University of Ulm, Diabetikerbund Bayern e. V., Diabetes-Journal, diabetes-online.de, and DiaExpert GmbH. In addition, people with T1D were recruited via social networks such as Facebook, Instagram, and various forums for patients with diabetes, as well as via diabetes bloggers. Attention was also drawn to the study via an information letter from a nursing expert in the department of Internal Medicine at the Marienhaus Klinikum Mainz (MKM). Statistical analyses were performed by using SPSS software.

One of the acceptance factors investigated in the study with regard to CGM system use was “digital affinity.” Based on this, two hypotheses were formulated and tested, which will be discussed in more detail below.

• H1a: Digital affinity has an influence on whether a CGM system is used (yes/no).

• H1b: Digital affinity has an influence on which CGM system is used, if one is used.

Digital affinity was consisting of the items “I like to use social networks (Facebook, Instagram, Twitter, . . .),” “I enjoy learning about new technologies,” “I store my data in clouds without hesitation,” “I generally get along well with technologies,” and “For me it would be important to display my glucose history on a watch (smartwatch),” with the response options of a 4-point Likert scale: “do not agree,” “rather do not agree,” “rather agree,” and “agree.”

First, the mean value of all five items was calculated to be 3.0429. Then, the Kolmogorov-Smirnov goodness-of-fit test was used to check whether digital affinity was normally distributed. With a sufficiently large sample size of n = 1642, the two-tailed P value after significance correction according to Lilliefors was 0.000 (P ≤ .05, P ≤ .01). Thus, a normal distribution could be excluded; non-parametric tests (Mann-Whitney U and Kruskal-Wallis) were used for further investigation. Ordinal data level as a minimum requirement for the dependent variable “digital affinity” was given.

For the Mann-Whitney U test, two independent samples were tested for significant differences based on the ranks of the dependent variable.

In the study, the independent variable was the use of CGM systems (“Are you currently using a CGM system [Continuous Glucose Monitoring System]?”). The hypothesis to be rejected in the Mann-Whitney U test is the H0 hypothesis, which states that there is no difference in the central tendency of the groups regarding their digital affinity or that the mean ranks of both groups are equal.

Thus, whether a CGM system is used depends on the digital affinity of a person with T1D, so that H1a could be confirmed. Then, it is also important to investigate which system is used (H1b) by using the Kruskal-Wallis test. It compares more than two independent samples based on the ranks of the dependent variable for significant differences and has the same prerequisites as the Mann-Whitney U test.

The hypothesis to be rejected in the Kruskal-Wallis test is the H0 hypothesis, which states that there is no difference between the medians of the three or more independent groups or that the dependent variable (here: digital affinity) has no difference in medians between the groups.

If both hypotheses are confirmed, then the item of app usage and the associated CGM system must subsequently be addressed to derive/present possible user preferences regarding the CGM system and digital affinity.

To investigate the extent to which digital affinity plays a role in the simultaneous use of a CGM system (“Are you currently using a CGM system (Continuous Glucose Monitoring system)?” and CSII by insulin pump (“What form of therapy is used for you?”) or for the use of HCL systems a cross tabulation was used. The same analysis was made for ICT by taking into account the factor of age (“How old are you?”).

Results

There is a significant correlation between digital affinity and the use of CGM systems (P = .000; P ≤ .05; P ≤ .01) (Table 1).

Table 1.

Correlation Between Digital Affinity and CGM System Use.

Mann-Whitney test
Ranks
	Use of CGM systems	N	Mean rank	Sum of ranks
Digital affinity (1 = low, 4 = high)	no	67	589.09	39 469.00
	yes	1575	831.39	1 309 434.00
	Total	1642
Test statistics a
		Digital affinity (1 = low, 4 = high)
Mann-Whitney U		37 191.000
Wilcoxon W		39 469.000
Z		−4.117
Asymptotic Significance (2-tailed)		.000

Abbreviation: CGM, continuous glucose monitoring.

^aGrouping variable: use of CGM system.

The effect size of this mean difference was calculated with 0.102 (r = |−4.117/√1.642|), indicating a medium or almost weak effect.

A significant difference (P ≤ .05, P ≤ .01) was found between the CGM systems “No-Dexcom G6” (P = .000) and “FreeStyle Libre 2 − Dexcom G6” (P = .000). The effect size of these mean differences between the groups “No-Dexcom G6” was 0.140, r = |4.741/√(67+1078)|, which indicates a medium effect, as well as for the groups “FreeStyle Libre 2 − Dexcom G6” with r = 0.130, r=|4.852/√(308+1078)|. Due to the highest number of users (n = 1078 and n = 308), the Dexcom G6 and FSL 2 systems were specifically used for the CGM comparison (Table 2).

Table 2.

Difference Between Groups of CGM Users Regarding to Digital Affinity.

Ranks
	Are you currently using a CGM system (Continuous Glucose Monitoring System)?	N	Mean rank
Digital affinity (1 = low, 4 = high)	Dexcom G4 PLATINUM	7	335.29
	Dexcom G5 Mobile	12	614.13
	Dexcom G6	1078	825.93
	Medtronic: Guardian Connect (with Enlite sensor and MiniMed 640G/ 670G insulin pump)	125	759.84
	Medtrum: A6 TouchCare (with patch pump)	2	875.00
	Roche/Senseonics: Eversense XL	29	841.43
	FreeStyle Libre	14	672.32
	FreeStyle Libre 2	308	683.41
	Total	1575
Test statisticsa,b
		Digital affinity (1 = low, 4 = high)
Kruskal-Wallis H		34.684
df		7
Asymptotic Significance		.000

Abbreviation: CGM, continuous glucose monitoring.

^aKruskal-Wallis test.

^bGrouping variable: Are you currently using a CGM system (Continuous Glucose Monitoring System)?

Both Hypotheses (H1a and H1b Could be Confirmed): Whether and Which CGM System to Use Depends on Digital Affinity

Figure 1 shows the 95% confidence interval (CI) for the mean of “Digital Affinity.” With a high digital affinity (4 = high), the CGM systems: Medtrum: A6 TouchCare (with patch pump), Roche/Senseonics: Eversense XL, and Dexcom G6 are preferred. The means of these systems are highest at 3.20. Medtrum with n = 2 and Roche/Senseonics with n = 29 fall out of consideration, as the sample size is too small (n < 30) to draw conclusions about the population. Thus, with a high digital affinity, the Dexcom G6 (n = 1078) is most preferred. Although the FSL 2 has only the sixth highest mean (out of a total of eight systems) of 2.92 with n = 308, it has a small range, so it should not be excluded from the study. The FSL (n = 14) falls out of closer examination despite its mean of 2.94. Like the FSL 2, the Medtronic: Guardian Connect (with Enlite sensor and MiniMed 640G/670G insulin pump) must also not be disregarded (at n = 125). Medtrum excluded, due to their high digital affinity mean of 3.11 (Dexcom G6) and 2.92 (FSL 2) and their smallest range, the Dexcom G6 and the FSL 2 are the two CGM systems with the highest potential for further investigation in complex technology.

Figure 1.

Digital affinity and CGM system use. Abbreviations: CI, confidence interval; CGM, continuous glucose monitoring.

With this in mind, it is important to also address the item of app usage and the associated CGM system (grouped) (Table 3). In the questionnaire, the item that examined the visual aesthetics of the CGM system was “The CGM system app is creatively designed.” A cross tabulation revealed that most users of Dexcom and Abbott (FreeStyle) as CGM system also used an app, n = 1097 (Dexcom), n = 322 (Abbott); N = 1575, not considered the non-user.

Table 3.

CGM System and App Usage.

Are you actively using a CGM system (grouped)? * (The CGM system app is creatively designed [visual aesthetics].)
			The CGM system app is creatively designed (visual aesthetics).
			Do not agree	Rather do not agree	Rather agree	Agree	Total
Are you actively using a CGM system (grouped)?	Dexcom	Count	163	303	437	194	1097
		Expected count	168.6	295.3	451.3	181.8	1097.0
	Medtronic	Count	38	37	40	10	125
		Expected count	19.2	33.7	51.4	20.7	125.0
	Medtrum	Count	0	0	2	0	2
		Expected count	0.3	0.5	0.8	0.3	2.0
	Roche/Senseonics	Count	4	4	14	7	29
		Expected count	4.5	7.8	11.9	4.8	29.0
	FreeStyle	Count	37	80	155	50	322
		Expected count	49.5	86.7	132.5	53.4	322.0
Total		Count	242	424	648	261	1575
		Expected count	242.0	424.0	648.0	261.0	1575.0

Abbreviation: CGM, continuous glucose monitoring.

Most patients with T1D and a high digital affinity (under ICT) use the Dexcom G6 as preferred CGM system (n = 69, digital affinity = 3.20 and 3.40, respectively). Medtronic users are rare under ICT (n = 2), because patients choose Dexcom or Abbott as their system (decision bias). The FSL 2, as the second most frequently preferred system, has the highest digital affinity at 2.80 (with n = 29). It can be seen that Abbott’s CGM systems can be built more complex for their patients with ICT in the future. Summarized, it can be stated that patients (T1D) using a FSL 2 have a lower digital affinity than Dexcom G6 users.

Most patients with T1D on insulin pump therapy (CSII) and a high digital affinity (here: 3.40) use the Dexcom G6 as their CGM system (n = 81). The FSL 2 scores with a digital affinity of 2.40 with only n = 15 users. This is due to the fact that a high digital affinity with simultaneous CSII therapy prefers the use of a Dexcom G6, which also ensures HCL therapy. So the Dexcom G6 is suitable for patients with a high digital affinity and may therefore be complex for T1D. Consequently, patients with T1D and a high digital affinity require a high level of digital competence (Supplementary Table 1, see Appendix).

The findings can also be confirmed with regard to age. The study showed that younger patients (T1D, treatment-independent) (18-25 years and 26-35 years) have a higher digital affinity than older patients (≥ 66 years) and thus prefer the Dexcom G6 over the FSL 2. In addition, it could also be seen that the digital affinity of young FSL 2 users was rated higher than that of young Dexcom G6 users, except in the group: CSII at the age of 18 to 25 years. Thus, the newly launched FSL 3 particularly covers the digital competence of young patients. In the older age groups, on the other hand, digital affinity is perceived to be lower by FSL 2 users with CSII therapy than by Dexcom G6 users (Supplementary Table 2, see Appendix).

Discussion

It is important to consider all of the acceptance factors examined in the study. Digital affinity plays a crucial role in the 21st century, because digitization will continue to advance in the future (eg, Corona crisis).^22,23

Therefore, special attention must be paid to the aspects of “use of social networks,” “willingness/interest to learn about new technologies,” “data storage in clouds,” “safe handling of technologies in general,” and particularly “desire for data transfer to a smartwatch” by medical technology companies. The development of new CGM systems but also new automated insulin delivery (AID) systems, which are interoperable with each other, are two important topics of future therapy care for the companies.

Especially, the companies Abbott (market leader in CGM systems, as of 2019) and Dexcom are already advancing on the path of digitalization. ²⁴ This is particularly evident when reading glucose values via the smartphone app or when transferring the data to a smartwatch.

In summary, persons with T1D who use either a Dexcom G6 or a FSL 2 as CGM system have a high enough digital affinity to make future CGM systems more complex. In particular, users of a Dexcom G6 have a high digital affinity regardless of their form of therapy (ICT, CSII).

This finding is in line with Abbott’s development in replacing the FSL 2 and launching the FSL 3 for this purpose. ²⁵ The Dexcom G7, which has just received its Conformité Européene (CE) mark, will also be coming to the German market soon. ²⁶

On the other hand, future CGM systems must not be developed with too much complexity if patients with T1D have a low digital affinity or a high age.

As a limitation of the study, it should be mentioned that the respondents were predominantly Dexcom users (n = 1097; 69.7%) compared with Abbott (n = 322; 20.4%). In addition, no crossover design was possible with respect to the used systems, because real-world data were used.

Conclusions

Digital affinity is considered as an important acceptance factor for people with T1D in Germany with regard to CGM system use. Not only whether a system is used, but also, which one, depends in part on digital affinity. In the present study, the Dexcom G6 was most preferred with a high digital affinity. Despite limitations of the study, it can be assumed that digital affinity is an important factor in the management of patients with diabetes provided with a CGM system. Especially young patients with T1D and a high digital affinity might accept further digitalization in diabetes control and treatment optimization.