The purpose of this study is to investigate if MOBIGAME (an innovative, mobile phone-based game application) is suitable to increase daily physical activity and physical activity adherence as well as health parameters such as cardiorespiratory fitness, leg strength, glucose metabolism, vascular health and self-determination as well as health related quality of life in the course of a 24-week intervention in comparison to the control group receiving one-time lifestyle counseling.

In recent years, type 2 diabetes mellitus (T2DM) has grown into an emerging pandemic that is a key determinant of morbidity and mortality in both developed and developing countries worldwide. The successful treatment and prevention of T2DM is one of the biggest future health care challenges and most important to manage the enormous socio-economic burden that is associated with T2DM and its various comorbidities. Physical inactivity is known to be one of the most important risk factors for the development of obesity and T2DM. In contrast, increases in physical activity (PA) and fitness can lower the T2DM incidence, improve the patient's glucose metabolism and reduce morbidity and (premature) mortality, independent of body mass index (BMI) or other risk factors. Despite the obvious benefits of regular PA in the treatment and prevention of T2DM, most activity-promoting programs targeting T2DM patients are seldom successful in the long term due to diminishing patient motivation. A novel approach to motivate those individuals that are the least likely to engage in regular PA to be more physically active and adhere to regular PA are active video games or "exergames" that combine PA and video gaming. However, existing exergames do not offer fitness-level adjusted, individualized workouts and are normally stationary and bound to a TV, thus not enabling PA anywhere and at any time. To address these shortcomings, the investigators used sports scientific expertise to develop a smartphone-based, mobile gardening simulation game application, specifically designed for middle-aged T2DM patients, to induce a healthier, more active lifestyle as part of a successful T2DM treatment and management.

Inclusion Criteria:

• Informed Consent as documented by signature
• Non-insulin-dependent diabetes mellitus (doctor diagnosed)
• Body Mass Index >25 kg/m2
• Regular smartphone use during the last year before the study
• Motivation to participate in the study for its entire duration of 24 weeks

Exclusion Criteria:

• Other clinically significant concomitant disease states (e.g., renal failure, hepatic dysfunction, cardiovascular disease, etc.),
• Inability to follow the procedures of the study, e.g. due to language problems, psychological disorders, dementia, etc. of the participant
• Previous enrolment into the current study
• Participation in other studies in the last four weeks
• Systolic blood pressure > 170mmHg, diastolic blood pressure > 100 mmHg
• Regular physical activity before the study (≥150 min moderate intensity daily PA per week or >1 endurance or strength training session per week of more than 30 min in duration)