In order to cure diabetes and atherosclerosis, we have investigated iron nanoparticles that were created using green chemistry principles and an extract from Trifolium repens leaves. Characterization of the green-synthesized iron nanoparticles was carried out using FT-IR, XRD, FE-SEM, UV-Vis, EDX, and TEM. The spherical form of the nanoparticles, which range in size from 20 to 50 nm, is confirmed by the results of morphological examinations. In the in vivo study, the iron nanoparticles were administered intragastrically in diabetic rats. The iron nanoparticles demonstrate the capability to lower the increased levels of GGT, ALT, AST, and ALP enzymes and blood glucose. The blood glucose levels of the untreated diabetic animals increased by almost 500% (p <= 0.05). When streptozotocin-diabetic rats were given iron nanoparticles at both dose levels, their fasting blood sugar levels were decreased (p <= 0.05), which was similar to what happened when glibenclamide was administered. Following treatment with iron nanoparticles, a marked decrease in the liver and its subcompartments' volume was observed. In another part of the in vivo design, triglycerides, total cholesterol, LDL, and HDL were assessed in Wistar rats with hypercholesterolemic diet-induced atherosclerosis. The findings showed that the iron nanoparticles shielded the vessel wall against early atherosclerotic alterations. The sham group had increased vascular wall thickness and smooth muscle cell proliferation, but the groups treated with iron nanoparticles did not exhibit similar pathological alterations. This study highlights the anti-diabetic and anti-atherosclerotic properties of iron nanoparticles, suggesting their potential as a supplementary measure to prevent atherosclerosis and gestational diabetes mellitus while simultaneously providing benefits for liver protection.