Psychological Factors and Self-Care Behaviors in Spanish Youth With Type 1 Diabetes: Age- and Sex-Based Comparisons and Associations

Psychological distress was assessed using the 2-item Diabetes Distress Scale (DDS2; short form of the Diabetes Distress Scale), a validated questionnaire that measures diabetes-related emotional burden and distress associated with disease management. The scale consists of two items scored from 1 to 6. The final score is calculated as the mean of the two item responses, resulting in a total score ranging from 1 to 6, with higher scores indicating greater diabetes-related psychological distress. A score of ≥3 is considered indicative of clinically significant diabetes distress.

Risk of eating disorders was assessed using the Diabetes Eating Problem Survey-Revised (DEPS-R), a validated questionnaire that screens for disordered eating behaviors in individuals with type 1 diabetes. The questionnaire consists of 16 items rated on a 5-point Likert scale (never, sometimes, often, usually, or always). The total score is calculated by summing the item responses, resulting in a score ranging from 0 to 80, with higher scores indicating greater risk of disordered eating behaviors. A score of ≥20 is considered indicative of risk for an eating disorder in adolescents with type 1 diabetes.

Self-perceived health status will be assessed using a single-item question ("How healthy do you think you are?"), rated on a 5-point Likert scale, where 1 represents "very unhealthy" and 5 represents "very healthy."

Age will be recorded in years at the time of study participation.

Gender will be self-reported by participants as part of the sociodemographic information.

Diabetes duration will be recorded as the number of years since the diagnosis of type 1 diabetes at the time of study participation.

Weight will be self-reported by participants in kilograms at the time of study participation.

Height will be self-reported by participants in centimeters at the time of study participation.

BMI was calculated as weight (kg) divided by height squared (m²).

Treatment adherence was assessed using the Diabetes Management Questionnaire (DMQ), a validated instrument that evaluates adherence to prescribed diabetes care regimens. The questionnaire consists of 20 items rated on a 5-point Likert scale. The total score is calculated by summing the item responses, with some items reverse-scored, resulting in a total score ranging from 0 to 100, with higher scores indicating better adherence to diabetes self-management and treatment recommendations. No established clinical cut-off values exist for adolescents with type 1 diabetes.

Adherence to the Mediterranean diet was assessed using the KIDMED questionnaire, a validated instrument that evaluates dietary habits and quality in young people. The questionnaire consists of 16 items with yes/no responses, with some items scored positively and others negatively. The total score is calculated by summing the item responses, resulting in a total score ranging from 0 to 12. Higher scores indicate better adherence to the Mediterranean diet. Adherence is categorized as follows: 8 points - Optimal Mediterranean diet, indicating excellent adherence; 4-7 points - Needs improvement, indicating a need to adjust dietary patterns toward the Mediterranean model; ≤3 points - Very low-quality diet, indicating poor adherence.

Physical activity was assessed using the Adolescent Physical Literacy Questionnaire (APALQ), a validated instrument that measures frequency, duration, and intensity of physical activity in young people. The questionnaire consists of 5 items rated on a Likert-type scale (never, 1-2 times a month, once a week, 2-3 times a week, and 4 or more times a week). The total score is calculated by summing the item responses, resulting in a total score ranging from 5 to 25, with higher scores indicating greater frequency and intensity of physical activity.