Sarcopenia is a condition characterized by the progressive loss of skeletal muscle mass and strength (1), which can lead to physical disability (2, 3), poor quality of life (4, 5), and increased mortality (6, 7). It is also associated with an increased risk of falls, which contributes substantially to healthcare costs, accounting for over $50 billion annually in medical expenses (8). In 2016, sarcopenia was officially recognized as a disease associated with aging by the World Health Organization and was assigned an ICD-10-CM code (M62.84) (9), reinforcing its clinical relevance and importance for public health (1). The prevalence varies between 10% and 27%, depending on the classification criteria used (10). Sarcopenia is particularly prevalent in older adults and can be exacerbated by chronic conditions such as type 2 diabetes mellitus (T2DM) (10). T2DM is one of the most commonly observed conditions and a significant contributor to sarcopenia among its various etiologies. T2DM is a metabolic disorder characterized by high blood sugar levels due to insulin resistance or insufficient insulin production (11, 12).

T2DM may also contribute to skeletal muscle degradation through extracellular matrix (ECM) remodeling, which disrupts insulin signaling and promotes muscle fibrosis and dysfunction, thereby accelerating sarcopenia progression (13). The combination of sarcopenia and T2DM in older adults poses significant health risks, including an increased likelihood of falls, fractures, and overall mortality (14). Currently, despite having a growing awareness of the impact of sarcopenia on health outcomes, significant gaps remain in understanding of sarcopenia affect mortality risk in older adults with T2DM. Although studies have investigated the link between sarcopenia and T2DM, comprehensive research examining their relationship in terms of increased mortality risk among older adults remains limited. To date, no systematic reviews or meta-analyses have been conducted on this topic. Understanding this relationship is crucial, as sarcopenia may not only worsen diabetes outcomes but also increase the risk of premature mortality. In fact, sarcopenia has been associated with up to a 45% higher risk of mortality in older adults compared to those without sarcopenia (15). This gap in knowledge underscores the need for an updated systematic review on the relationship between sarcopenia and mortality. This review aims to examine the association between sarcopenia and all-cause mortality in older adults with T2DM, while considering whether this relationship varies based on the population, the definition of sarcopenia, and the duration of follow-up. This will pave the way for developing effective treatment strategies to manage both conditions concurrently, ultimately improving health outcomes and survival rates.

Sarcopenia and T2DM are two health conditions that significantly impact mortality risk, particularly in older adults (17, 18). Investigating the relationship between these conditions can provide valuable insights into the associated risks and guide more effective management strategies. Older people diagnosed with T2DM experience a more pronounced and accelerated decline in both muscle mass (19, 20) and muscle strength (21, 22) compared to those without diabetes. T2DM is associated with a reduction in key components used to diagnose sarcopenia. Therefore, sarcopenia and T2DM coexist, the risk of mortality increases significantly. Individuals with both conditions tend to have poorer overall health and face a higher likelihood of severe complications and mortality (23, 24). This combination leads to a marked decline in physical health, further elevating the chances of serious complications and mortality.

Simultaneously studying sarcopenia and T2DM is essential for developing effective health management strategies that reduce mortality risk and improve the quality of life in older adults. A deeper understanding of the relationship between these conditions can drive more impactful research and enhance medical practices in caring for older adults. Current studies on sarcopenia and T2DM present mixed findings and fail to offer a clear understanding of the relationship between these conditions and mortality risk. A meta-analysis could integrate the available data, reduce heterogeneity, and enhance the precision of risk assessment. This approach would also provide greater insight into the combined effects of sarcopenia and T2DM on mortality, addressing an important research gap that requires further investigation.

However, several limitations should be considered. First, variations in the diagnostic criteria for sarcopenia (e.g., EWGSOP2, and AWGS) across studies may introduce heterogeneity that could affect the comparability of results. Second, differences in population characteristics, such as ethnicity and healthcare settings, may limit the generalizability of the findings. Third, the inclusion of only English-language publications may lead to language bias. Lastly, publication bias and the inherent limitations of observational studies (e.g., residual confounding) may also influence the pooled estimates.