Diabetes mellitus (DM) is a common endocrine disorder that affects more than 10% of the adult population globally, 90% of which are type 2 DM (T2DM).  DM was extrapolated to affect 20.5% of adult Jordanians by 2025, and around 50% of Jordanians attending dental clinics are at a moderate to high risk of developing T2DM in 10 years.

The main morbidities of DM are angiopathy, nephropathy, retinopathy, and neuropathy rendering diabetic patients at a higher risk of myocardial infarctions, chronic kidney disease, blindness, and peripheral neuropathological impairment respectively.  The common oral features associated with DM include gingivitis/periodontitis, dental caries, candidosis, xerostomia, sialosis, bacterial sialadenitis, burning mouth, halitosis, and dysgeusia.  DM is also accused of being a risk factor for the development of oral/head and neck cancer, potentially malignant disorders and oral lichen planus.

Metformin is the first-line treatment of T2DM with versatile use.  In addition to its blood glucose-lowering effect, metformin has pleiotropic effects that may influence patients' oral health and dental management. Metformin therapy has a positive impact on oral health such as decreasing the risk of gingivitis/periodontitis, ameliorating the xerostomia, accelerating the healing of periapical pathology following endodontic treatment, increasing the success rate of the dental implant and lowering the incidence and mortality rate of oral cancer, in addition to its anti-microbial activity.  On the other hand, metformin has a bitter taste, may cause taste alterations, decreases the orthodontic tooth movement rate, and can induce oral lichenoid reaction.  For optimum dental and medical healthcare, providers should be fully aware of the oral manifestation associated with DM and metformin therapy.