Diactive-1: Scaled-up Personalized mHealth Program for Youth With Type 1 Diabetes

Handgrip strength measured in kilograms using the Takei III Smedley Type Digital Dynamometer

The daily insulin dose requirements will be measured in units per kilogram of body weight. Assessment will rely on participant-reported data from insulin pumps or injection logs, gathered for 7 days prior to the intervention and after the intervention.

Glycated hemoglobin (measured in percent)

Number of participants with a glycated hemoglobin level lower than 7%

The percentage of time a person spends with their blood glucose levels in the target range (70-180 mg/dL or 3.9-10 mmol/L) (measured in percent)

The percentage of time a person spends with their blood glucose levels below the target range (<70 mg/dL or <3.9 mmol/L, i.e., hypoglycemia) (measured in percent)

The percentage of time a person spends with their blood glucose levels above the target range (>180 mg/dL or 10 mmol/L, i.e., hyperglycemia) (measured in percent).

Glycemic variability measures the fluctuation in blood glucose levels over time, expressed as a percentage. Lower glycemic variability indicates more stable levels, while higher glycemic variability suggests greater fluctuations.

Physical activity at different intensities (average min/day), sedentary time (average min/day) and sleep (average min/day) will be measured using self-reported questionnaires.

Aerobic and muscle-strengthening activities will be assessed using two separate ad hoc questions. Participants will have response options ranging from 0 to 7 days per week, with increments of 1 day.

The International Fitness Scale (IFIS) will be used to assess self-reported physical fitness. This scale includes five elements that will employ a 5-point Likert scale to inquire about children's overall perception of their physical fitness, as well as their perception of their cardiorespiratory fitness, muscular fitness, speed-agility, and flexibility compared to their peers. The Likert scale will provide choices ranging from 'very poor' to 'poor,' 'average,' 'good,' and 'very good' physical fitness.

Sleep duration will be determined by recording the number of hours slept each day

Physical literacy will be assessed using the Spanish Perceived Physical Literacy Instrument (S-PPLI), a 9-item questionnaire that evaluates three dimensions: knowledge and understanding; self-expression and communication; and sense of self and self-confidence

We will use the Spanish adaptation of the Physical Activity Barriers Scale for pediatric type 1 diabetes (PABS-1), a validated instrument for assessing perceived barriers to physical activity in children and adolescents with type 1 diabetes

For assessing adherence to the Mediterranean Diet, the KIDMED index will be employed. This index provides a score on a scale of 0 to 12, with higher scores indicating stronger adherence.

Disordered eating will be screened using the mSCOFF questionnaire. This questionnaire consists of six straightforward yes/no questions. A positive response to two or more of these questions suggests a potential eating disorder, often requiring further evaluation.

Subjective well-being will be assessed using the CUBE questionnaire, which comprises five items that evaluate different aspects of life satisfaction and emotional states.

Health-Related Quality of Life will be evaluated using the Screening for and Promotion of Health-Related Quality of Life in Children and Adolescents (KIDSCREEN-10).

Health-Related Quality of Life in the context of a chronic illness will be evaluated using the Spanish version of the 'Questionnaire for Young People with Diabetes' (DISABKIDS).

Microalbuminuria will be evaluated as an indicator of early kidney involvement. A first-morning urine sample will be collected, and the albumin-to-creatinine ratio (ACR) will be determined using standardized laboratory procedures. Values will be expressed in mg/g. Microalbuminuria will be defined as an ACR between 30 and 300 mg/g, according to international diabetes guidelines.

Retinal imaging will be performed to assess early signs of diabetic retinopathy. Images of both eyes will be captured following standard ophthalmologic protocols and evaluated by trained specialists. Findings will be categorized as no retinopathy, mild, moderate, or severe diabetic retinopathy, based on international classification criteria.

Weight and height will be combined to report body mass index in kg/m^2

The usability of the app will be evaluated using the Spanish Version of the User Version of the Mobile Application Rating Scale (uMARS).

We will employ the Spanish adaptation of the Mobile Application Rating Scale (MARS), a standardized instrument for expert appraisal of mHealth applications.