Figure 6c shows a significant negative correlation between insulin levels and sarcopenia (SMD = −0.70, 95% CI (−0.94, −0.45), K = 9, N = 10,032, I2 = 93.5%). Among the nine studies, only the research by Hyung Eun Shin et al. (2022) [54] showed reduced insulin levels in individuals with sarcopenia. In the subgroup analysis, a negative correlation was found in the sarcopenia population aged <75 years, community populations, and those in developing countries with a higher proportion of males (Figure S34). No correlation was observed between insulin levels and the SO population (Figure S35). The gene discussed is INS; the disease is sarcopenia.