The objective of the study is to describe the effect of mobile app usage on glycated hemoglobin for the management of adult patients with type 2 diabetes mellitus who participated in randomized controlled clinical trials.

To achieve this, a systematic review will be conducted on scientific publications from the last 5 years (January 2019 to October 2023), considering the following guiding question: How effective are mobile apps in managing people with type 2 diabetes mellitus? A descriptive and comparative analysis will be carried out on the differences in the level of HbA1c, looking for results in absolute values or changes between the beginning and the end of the intervention.

The systematic review protocol was designed following the recommendations of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses protocols [13] and will adhere to the standard methodological norms established by the Cochrane Collaboration [14]. The corresponding protocol has been registered in the International Prospective Register of Systematic Reviews (PROSPERO) at the University of York. Its registration number is CRD42023475528.

The search will be carried out in the MEDLINE (Ovid), Embase (Ovid), CINAHL (EBSCOhost), CENTRAL, WoS, Scopus, Epistemonikos and LILACS databases. The search strategy will be constructed with controlled and natural language. In addition, the Cochrane filter will be added to identify randomized controlled trials (RCTs). The bibliographic search will be conducted iteratively using keywords that correspond to the structure of the question, creating an adapted process by combining search terms using the Boolean operators "AND" to combine domains and "OR" for terms within the same domain. The search will be limited to the last 5 years. The results of the search strategy will be synthesized using a PRISMA flow diagram (Fig 1) [15].

A progressive approach will be used in the search for the inclusion of studies, which involves selecting the publications, first by analyzing the titles, and then evaluating the methodological aspects with an analysis of the abstracts. Two independent evaluators will review the selected texts. In cases where there is no agreement on a publication, a third author will be asked to act as a referee to decide on the selection (inclusion or exclusion of the study). The search results will be managed using Rayyan, an online platform that facilitates the process of detection of duplicates and assists in the blind assessment of eligibility among independent elimination reviewers [16, 17].

The review will include scientific articles reporting studies that present results from randomized controlled trials (RCTs), published in the last 5 years, with text in Spanish, English, or French, that utilize mobile applications for the management of adults (over 18 years old) with type 2 diabetes mellitus (T2DM), and whose results report effects on HbA1c. The inclusion of studies will not be limited when participants have coexisting chronic diseases. A mobile application is defined as software installed on the user’s cell phone, composed of modules in which various information is provided (use of medications, healthy habits, education about the disease, support for self-management, among other aspects).

On the other hand, publications that correspond to protocols, those not available in full text (for example, abstracts published in conference proceedings), and those that, referring to the use of technologies, use only text messages, emails, social networks, or phone calls, will be excluded from the study. Studies that do not provide data on the effects on HbA1c will also be excluded, as this is the primary outcome to be collected in this review, those whose design is not an RCT, and those that include a pediatric population among the participants.

The publications will be analyzed by observing the HbA1c level values of the participants in the RCTs. Since this data is quantitative and continuous, i.e., more objective, it facilitates the identification of the effects of mobile applications used for managing Type 2 Diabetes Mellitus in adults. This information will be transferred to an Excel spreadsheet. Furthermore, if sufficient data are available, a meta-analysis will be conducted using IBM-SPSS. The effect of the intervention will be estimated using the mean difference. The mean difference (MD) will be used as a summary statistic for continuous outcomes. The standardized mean difference (SMD) will be estimated if the results are reported on different scales. All point estimators will be accompanied by 95% confidence intervals (95% CI). A random-effects model will be used. Heterogeneity of results will be assessed using Cochrane’s Q and I2 statistics. The I2 statistic measures the between-study variation that cannot be attributed to chance and is expressed as a percentage. It is often classified as low, moderate, and high heterogeneity when the I2 value is <25%, 25 to 50%, and >50%, respectively. The fixed effects model will only be considered when the results are homogeneous (I2<25%) [22, 23].

Publication bias will be assessed using a funnel plot and Egger’s test. All analyses will be performed in Review Manager (RevMan) (version 5.2, Copenhagen: The Nordic Cochrane Centre, Cochrane Collaboration, 2012) [24]

In this systematic review, the primary outcome will be the level of glycated hemoglobin (HbA1c) obtained after the intervention. The results reported in the studies, whether they are absolute values or changes in levels between the start and end of the intervention, will be considered.