 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 patients 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. 