INS and diabetes mellitus: Patients with severe periodontitis usually have unfavourable blood glucose control and are more likely to have diabetes-related complications, such as cardiovascular disease, retinopathy, or diabetes neuropathy.5 Diabetes is a metabolic disease with high fatality and disability rates worldwide.6 By 2030, the number of diabetes patients worldwide may reach 552 million.7 Approximately 90% of diabetes patients suffer from type 2 diabetes, whose main pathological feature is ineffective insulin use by the body which leads to insulin resistance (IR).