Osteoporosis is a common diabetic consequence that negatively affects patients' health and quality of life. Nevertheless, there is mutual interference between clinical drugs intended to regulate blood glucose and bone metabolism. Therefore, it is crucial to look for new treatment targets that effectively control blood glucose and safely protect the bone health of patients with diabetes. In this study, mice given a high-fat diet were shown to be resistant to osteoporosis and diabetes when protein phosphatase 5 (PP5) knockout (KO) mice were used. Serum markers of bone remodeling show that PP5 KO mice are resistant to decreased bone formation and increased bone resorption brought on by diabetes. The absence of PP5 resists the reduction of osteoblast differentiation and the enhancement of osteoclast differentiation in diabetic mice, according to the in vitro osteoblast differentiation of bone mesenchymal stem cells and osteoclast differentiation of bone marrow-derived macrophages. Subsequent investigation revealed that PP5 deficiency increases the expression of the key regulator of osteoblast differentiation, runt-related transcription factor 2, and decreases the activity of the receptor activator of the nuclear factor-κB ligand/osteoprotegerin pathway, a crucial regulatory signaling pathway for osteoclast differentiation. In conclusion, we discovered that PP5 deficiency protects diabetic mice against osteoporosis for the first time.