This review is to systematically explore the relationship between muscle dysfunction and diabetes in adults, and to examine the impact of glycemic variability on muscle health and the development of diabetes-related complications. The review was conducted using three databases: MEDLINE, Scopus, and EMBASE, targeting peer-reviewed journal articles written in English and published from January 2014 to September 2024. The methodological quality assessment of the eligible studies was conducted using Joanna Briggs Institute Critical Appraisal Checklists. A total of 17 studies were included. Most studies were undertaken in Asian countries (n = 11) and focused on adults with type 2 diabetes (n = 12). There were 8,392 adults with diabetes, and their mean age ranged from 52 to 75 years old. The measurements for muscle function and glycemic variability varied across studies. The research findings regarding the relationship between muscle dysfunction and glycemic variability metrics among adults with diabetes, both with and without complications were inconsistent. For adults with diabetes and sarcopenic obesity, poor glycemic control was identified as an independent risk factor for sarcopenic obesity. Additionally, all included studies were rated as moderate or high quality in relation to their methodology. In conclusion, this review underscores the complex and inconsistent relationship between glycemic variability and muscle dysfunction in older adults with diabetes. Poor glycemic management is a significant risk factor for sarcopenic obesity, highlighting the need for tailored interventions to improve glycemic control and muscle health in this population.