Background and objective:
Poor oral health and type 2 diabetes mellitus (T2DM) are chronic conditions affecting a wide proportion of the population. Both conditions share many risk factors and are linked by a chronic inflammation state. This review aimed at identifying public health interventions that could promote oral health and diabetes control in patients with poor oral health and T2DM.

Methods:
The systematic review was performed according to the PRISMA Statement and registered in the International Prospective Register of Systematic Reviews (PROSPERO registration: CRD42022310974). Seven electronic databases were searched (PubMed, Scopus, Embase, Web of Science, CINAHL, PsycInfo, Cochrane Library) from inception to 21 January 2022, and additional hand searching was performed across reviews’ references. A qualitative analysis was conducted, including all primary studies on diabetic patients, about interventions whose effectiveness and/or feasibility was measured for at least one outcome related to oral health or T2DM.

Results:
Of the 3153 records obtained after deduplication, 89 studies were considered eligible for inclusion. The most frequently evaluated outcomes were HbA1c and fasting glucose for T2DM, and parameters such as probing depth, bleeding on probing and clinical attachment loss for periodontitis. Most studies assessed the use of non-surgical periodontal treatment (especially scaling and root planing, sometimes corroborated by antibiotics): evidence confirmed effectiveness on periodontal parameters, but was more contrasting regarding T2DM outcomes. Three studies evaluated interventions involving group education for lifestyle modification, which showed to be effective on both outcomes. Also, community-based oral hygiene interventions and glycaemic control appeared to improve T2DM and periodontal outcomes.

Conclusions:
A variety of interventions are described in the literature. Of those included in this review, many indicated that there is a potential opportunity to promote good oral health alongside T2DM. An integrated approach involving health education, oral hygiene and glycaemic control may offer synergic improvement of both conditions.