The aim of this study was synthesize and evaluate the effects of Poly (D, L-Lactide-co-glycolide) (PLGA) Nanoparticles (NPs) of metformin (PLGA+ Met) on inflammation, and bone loss in a ligature-induced periodontitis rat model. The prepared NPs were characterized by mean diameter, size particle, polydispensity index and encapsulation efficiency by Atomic force microscopy (AFM). Male albino Wistar rats were randomly divided into four groups of 20 rats in each group, and given the following treatments for 10 days to evaluate in vivo activity: (1) Sham: no ligature + water; (2) Positive control: ligature + water (with Periodontal disease and Diabetes); (3) ligature + PLGA+ 10 mg/kg Met (With Periodontal disease and Diabetes); and (4) ligature + PLGA+ 100 mg/kg Met (with Periodontal disease and Diabetes). Water or PLGA + Met was administered orally by gavage. Maxillae were fixed and scanned using Micro-computed Tomography (μCT) to quantify linear of bone loss. Histopathological characteristics were assessed through immunohistochemical staining for Osteocalcin, Cathepsyn K, RANKL/RANK/OPG pathway. IL-1β and TNF-α from gingival tissues were analysed by Elisa immunoassay. Quantitative RT-PCR reaction was used to evaluate gene expression of AMPK, NF-κB p-65, Hmgb1 and TAK-1 from gingival tissues. Statistical analysis was performed using one-way ANOVA at 5% significance. The mean diameter of MET-loaded PLGA nanoparticles was in a range of 457.1 ± 48.9 nm with a polydispersity index of 0.285, zeta potential: 8.16 ± 1.1 mV and entrapment efficiency (EE) was 70%. The results suggest that the addition of MET in the core slightly affected the particle sizes. Treatment with PLGA+ 10 mg/kg Met showed low inflammatory cells, decreased bone loss and integrity cement and levels of IL-1β, and TNF-α (p < 0.05) were significantly reduced. Additionally, weak staining was shown by RANKL, Cathepsyn K, OPG, and osteocalcin. Radiographically, linear measurements showed a statistically significant reduction in bone loss after treatment with PLGA+ 10 mg/kg Met compared to the positive control (p < 0.05). RT-PCR showed increased AMPK expression (p < 0.05) and decreased expression of NF-κB P65, HMGB1 and TAK-1 after PLGA+ 10 mg/kg Met (p < 0.05). The PLGA nanoparticle + 10 mg/kg Met decreased glucose levels and also decreased the inflammatory response, and bone loss in ligature-induced periodontitis in rats.