Background <p>Malnutrition is a common geriatric syndrome among older adults and is linked to other geriatric syndromes, such as dementia, falls, frailty, and sarcopenia. In 2019, the Global Leadership Initiative on Malnutrition (GLIM) introduced new criteria for diagnosing malnutrition.</p> Aim <p>This study aimed to compare the relationship between malnutrition and other geriatric syndromes using the GLIM and Mini Nutritional Assessment Short Form (MNA-SF).</p> Methods <p>This retrospective observational study included 228 geriatric outpatients enrolled between April 2023 and June 2024. MNA-SF 0–7 scores indicate malnutrition. The GLIM criteria were applied, except for low muscle mass, which was substituted by low hand-grip strength (GLIM-HG). Frailty, depression, chronic pain, polypharmacy, probable sarcopenia, urinary incontinence, and falls were also evaluated.</p> Results <p>Malnutrition rates were 6.6%, 21.1%, and 29.8% according to the MNA-SF, GLIM, and GLIM-HG, respectively. After screening for malnutrition using the MNA-SF, a second evaluation with the GLIM was performed for patients with malnutrition and at risk of malnutrition. Malnutrition was 17.5% with two-step GLIM. MNA-SF, GLIM, and two-step GLIM were significantly associated with falls, depression, probable sarcopenia, and frailty. According to the MNA-SF, malnutrition showed the strongest association with falls, depression, and frailty. The agreement between MNA-SF and GLIM was moderate (κ = 0.383; 95% CI: 0.232–0.533), whereas the agreement between GLIM and two-step GLIM was strong (κ = 0.888; 95% CI: 0.812–0.964).</p> Conclusion <p>The GLIM criteria are useful in outpatient settings. Applying GLIM after nutritional risk screening may help reduce the risk of overdiagnosis.</p>