Contextual effects of monetary incentives on acceptance of unfair offers in the ultimatum game.

Type 2 diabetes mellitus (T2DM) is a major global health burden, with the affected population expected to rise to 1.31 billion by 2050. Although T2DM is already highly prevalent, its incidence continues to rise globally, probably due to environmental pollution, dietary shifts, and increasingly sedentary lifestyles. Despite advances in pharmacological treatment, current approaches for T2DM remain reactive and insufficient to counter the rising incidence. Thus, identifying individuals at high risk of type 2 diabetes is crucial for effective primary prevention. Several studies have found that physical activity (PA) is a key strategy for the prevention of T2DM. In reality, PA exists on a continuous spectrum and can be categorized into moderate-to-vigorous intensity physical activity (MVPA) and light-intensity physical activity (LPA). Evidence of its dose-dependent effect remains uncertain, particularly concerning whether small increases in activity yield meaningful preventive benefits. Sedentary behavior, representing the opposite end of the movement spectrum, has been associated with increased metabolic risk. However, the extent to which sedentary behavior is associated with the risk of T2DM remains unclear. Importantly, methodological limitations, particularly the widespread reliance on self-reported PA data that are prone to recall bias and social desirability, have likely contributed to inconsistencies in the literature and hindered accurate effect estimation. As highlighted by pivotal research, objective physical activity measures yield more robust risk estimates for cardiometabolic diseases compared with self-reported methods. Employing objective PA assessment methods is therefore essential to accurately quantify dose–response relationships and clarify the long-term preventive impact of PA on T2DM, a concept increasingly supported by recent accelerometer-based prospective studies. The metabolic benefits of physical activity are fundamentally dependent on the functional capacity of skeletal muscle, which serves as the primary tissue for insulin-mediated glucose uptake. Consequently, evaluating movement behaviors independently of an individual’s underlying muscle health may provide an incomplete assessment of their diabetes risk. Sarcopenia status, characterized by the progressive loss of muscle mass and physical function, is increasingly common among older adults. Reduction in muscle mass may contribute to insulin resistance and impaired glucose metabolism. While associations between muscle mass and T2DM have been examined in prior studies, most relied on self-reported physical activity data that are prone to substantial recall bias, limiting the precision of dose-response relationships. Moreover, few studies have comprehensively assessed sarcopenia status (a combined phenotype of reduced muscle quantity and function) in relation to incident T2DM. Critically, it remains unknown whether sarcopenia components (particularly grip strength) modify the protective effect of objectively measured physical activity on T2DM risk.