Background: Worldwide increasing rates of prediabetes and type 2 diabetes are creating a significant public health challenge, and treatment strategies should integrate physical and mental health care. Studies have shown that physical activity plays a role in reducing the complications associated with type 2 diabetes. However, there has been little randomized controlled trial evidence of any sustained impact on the prevention of mental disorders by such implementation. Ecological issues, primarily climate variables, can also interfere with physical activity levels, but how they influence individual daily life, especially for people with chronic diseases, will require considerable research. The integration of eHealth tools could facilitate self-management. More research is required concerning end-user's perceptions of electronics health (eHealth) technologies in primary care settings to enable physical to be promoted effectively. Thus, this thesis aimed to evaluate the effects of a physical activity promotion intervention—both with and without counseling—on preventing mental illness in individuals with prediabetes or type 2 diabetes. It also investigated associations between physical inactivity and comorbidities with mental health trajectories, explored the relationship between weather variations and daily self-monitored step counts over two years, and examined perspectives on eHealth technology for promoting physical activity in primary care.

Methods: Study I, a three-armed randomized controlled trial, was conducted with adults diagnosed with prediabetes or type 2 diabetes recruited from primary care settings. Participants were assigned to a multi-component intervention group (self-monitoring steps with counseling), a single-component intervention group (self-monitoring only), or a standard care control group. Mental health symptoms, comprising depression and anxiety assessed with the Hospital Anxiety and Depression Scale, perceived stress measured with the Perceived Stress Scale, diabetes distress evaluated with the Problem Areas in Diabetes Scale, and health-related quality of life as evaluated with the EuroQol EQ-5D-3L, were assessed at baseline and 12-, 24-, 48-, and 96-weeks postintervention. Analyses employed a robust linear mixed-effects model. This longitudinal study also included data from the Sophia Step Study, study II, which evaluated mental health at baseline, two years, and 5-9 years. We used the mental health assessment instruments in Study I applied also in Study II, except for the instrument for diabetes distress assessment, and used only the EQ-5D visual analog scale in the quality-of-life  assessment. Baseline physical activity levels measured by accelerometers were dichotomized based on whether the participants met the World Health Organization's recommendation for 150 minutes per week of moderate to vigorous-intensity physical activity. Study III was conducted using data from the Sophia Step Study. The daily step counts using self-reported data and environmental factors (daily average temperature, precipitation, and hours of sunshine) from the Swedish Meteorological and Hydrological Institute employed in the analysis. A robust linear mixed-effects model examined the association between weather variations and daily selfmonitored steps. To explore eHealth perspectives, qualitative focus group discussions were conducted with  prediabetic and type 2 diabetic individuals and healthcare providers, followed by qualitative content analysis.

Results: The randomized controlled trial (Study I) revealed no significant changes in mental health symptoms from baseline to 24 months, nor any significant differences between intervention and control groups. Study II indicated that physical inactivity and comorbidities did not significantly impact mental health outcomes, while female sex, longer disease duration, and higher BMI were associated with increased anxiety and depression. The Secondary Analysis (Study III) produced no significant indications that variations in weather influenced daily step counts, with only 10% of variance explained by the weather; individual characteristics constituted 38%. The qualitative analysis uncovered themes of utility, the adoption process, and accountability related to eHealth tools, which are motivational but also raise accessibility concerns.

Discussion/conclusion: In study I, the findings suggest that structured interventions promoting physical activity were not effective in preventing mental health in individuals with prediabetes and type 2 diabetes since stable mental health was observed throughout the study. Study II revealed that physical activity levels and comorbidities were not significantly associated with mental health outcomes over time. However, the individual characteristics, such as a longer duration of type 2 diabetes and female gender, were positively correlated with anxiety and perceived stress. In addition, subjects with BMI ≥ 30 kg/m² were at risk for depression and low quality of life. Weather variation, as in Study III, influences could only be associated with daily step counts of 10%. Still, weather variations account for more than 38% of individual factors like gender, age, and BMI, which could influence existing physical activity levels. Finally, using eHealth technologies in Study IV seemed encouraging for self-management approaches. However, there is still a lack of resolution of the issues relating to eHealth illiteracy and the additional strain placed upon healthcare providers.

The thesis presented, therefore, essential lessons concerning the multifaceted nature of promoting physical activity and mental health management for those with prediabetes and type 2 diabetes. It underlines the necessity of future research to help develop refined interventions focusing on personalized support while integrating eHealth effectively in primary care settings. Future work must optimize community strategies that promote physical activity integrated with eHealth tools to improve health outcomes in this population.