This study aimed to investigate the relationship between the sarcopenia index (SI), which is derived from serum creatinine and cystatin C levels, and osteoporosis in chronic kidney disease (CKD). This study initially included patients who underwent dual-energy X-ray absorptiometry (DXA) and serum creatinine and cystatin C testing between 2005 and 2022. Subsequently, patients diagnosed with CKD were selected for the final analysis, totaling 102 patients. Both traditional and new SI were calculated, with each participant categorized into one of two groups (non-osteoporosis and osteoporosis) according to bone mineral density. To enhance statistical validity, the patients were further divided into low- and high-index groups based on the median value of both indices for comparative analysis. The association between SI and the risk of osteoporosis was estimated using multivariable logistic regression analysis. Participants with lower SI values had lower bone mineral density and a higher diabetes mellitus prevalence. The non-osteoporotic group exhibited significantly higher mean values for both traditional and new SI. Multivariable logistic regression analysis identified three statistically significant variables: both indices, sex, and diabetes mellitus. Both traditional and new SI yielded individual odds ratios of 0.906 with estimated areas under the curve of 0.847 for traditional SI and 0.833 for new SI. This study confirmed that both traditional and new SI are associated with osteoporosis in patients with CKD. Therefore, clinicians can raise the suspicion of osteoporosis based on traditional and new SI in patients with CKD, even when DXA results are unavailable.