Objective: Obesity and diabetes mellitus (DM) are major risk factors for osteoarthritis (OA), but it remains unclear how comorbidity affects apoptosis signaling in OA. This study investigated the effect of metabolic diseases on apoptosis and apoptosis-related intracellular and extracellular signaling in OA. Methods: Excision materials of human articular cartilage from total knee arthroplasties were collected. The samples were divided into four groups as, control OA, OA+DM, OA+Obese, and OA+DM+obesity. Protein activities were determined using Western blot and ELISA. Results: Caspase-3 levels were significantly increased in chondrocytes in which OA was associated with DM or obesity. However, an increase in Bcl-2 activity was also observed in these comorbidities. The increased levels of CaMKII in the same groups also indicate an increase in cellular activity in comorbidities. While IL-6 and TNF-α did not show significant changes, matrix regulatory protein CYR61 levels reflected the intracellular apoptotic activity. Conclusion: Metabolic diseases have a stimulatory effect on the etiopathology of osteoarthritis by enhancing cellular signaling towards apoptosis and that matrix signaling proteins may play a key role in regulating these effects. Examining OA with its accompanying diseases will lead to a better understanding of the cellular mechanisms that differ in OA.