Distinguishing osteoporosis in older adults with type 2 diabetes mellitus (T2DM) remains clinically challenging because metabolic and skeletal abnormalities often coexist. Blood biomarkers that reflect these changes may support earlier identification of osteoporosis in this population.

A retrospective study published in the Journal of Diabetes Investigation examined the relationship of serum C1q/tumor necrosis factor-related protein 3 (CTRP3) and cystatin C (CysC) with metabolic indicators and bone health parameters in older adults with T2DM. The analysis included 235 patients with T2DM treated at Taizhou Municipal Hospital between January 2021 and June 2024. Patients were categorized into a T2DM group (n = 131) and a T2DM with osteoporosis group (n = 104). An additional control group included 95 older adults without diabetes or osteoporosis.

Serum CTRP3 concentrations were lower, and CysC levels were higher in individuals with T2DM and osteoporosis. Both biomarkers showed correlations with indicators of glucose and lipid metabolism, bone metabolism markers, and bone mineral density. Diagnostic analysis showed moderate discriminatory performance for each biomarker individually, with area under the curve values of 0.719 for CTRP3 and 0.702 for CysC. When evaluated together, the biomarkers showed improved discrimination for T2DM complicated by osteoporosis, with an AUC of 0.773, sensitivity of 76.92%, and specificity of 64.89%.

Multivariable analysis indicated that higher CysC levels were independently associated with T2DM accompanied by osteoporosis (OR 1.422; 95% CI 1.161-1.742), while CTRP3 showed an inverse association (OR 0.960; 95% CI 0.943-0.976). These findings suggest that combined measurement of CTRP3 and CysC may assist in distinguishing osteoporosis among older adults with T2DM.