BackgroundTo assess the efficiency of periodontal treatment (PT) in improving diabetes‐related outcomes in adults with type 2 diabetes mellitus (T2DM) and periodontitis, providing an updated and comprehensive synthesis from economic evaluations (EE).MethodsSeven databases and one register were independently searched by two reviewers for articles published up to 8 May 2024. Studies that assessed the efficiency of PT versus no treatment or other dental treatments were included. Risk of bias was assessed using the Cochrane RoB 2, ROBINS‐I and ECOBIAS tools for the first stage of EE and the CHEERS checklist and NICE quality appraisal tool for overall EE. Qualitative and quantitative syntheses of the articles were conducted and assessed using the GRADE approach.ResultsEleven studies were included. PT reduces total healthcare costs, including inpatient and outpatient, diabetes‐related costs and other drug costs (low to moderate certainty). A total incremental net benefit of USD 12 348 (2022 currency, 95% CI 12 195–12 500) was estimated from three high‐quality model‐based cost‐utility analyses (high certainty).DiscussionThe inclusion of PT in the comprehensive treatment of patients with T2DM and periodontitis is cost‐effective. Future research is required to ensure the transferability of these findings and inform decision makers from different countries.RegistrationPROSPERO CRD42023443146.