Should we prescribe systemic antibiotics alongside periodontal therapy for diabetic patients?

This single-centre, short-term randomized control trial (RCT) assesses the effect of systemic amoxicillin and metronidazole as an adjunct to SRP in patients with severe periodontitis and type 2 diabetes mellitus (T2DM) on glycaemic control, over a 3-month period. The authors hypothesize that adjunctive systemic antibiotics will decrease systemic inflammation and subsequently improve glucose control. Baseline periodontal examinations and haematological tests were performed for all subjects. Subsequently, subgingival scaling and root planning (SRP) procedures were performed by a single periodontist for both the test and control groups. The test group received 500 mg amoxicillin and 200 mg metronidazole TDS for 7 days in the same week of the SRP procedure. Three months later, periodontal examinations were repeated by blinded examiners and haematological tests were repeated. Maintenance periodontal therapy was provided at this time.

A convenience sample of patients visiting the periodontal department between 2016-2022 was used. Participants included were aged 40-75; diagnosed with T2DM for >2 years; HbA1c of 6.5-10%, had stable medication regimens and >15 remaining teeth. Participants had a periodontal diagnosis of generalized severe chronic periodontitis or stage III-IV generalized periodontitis based on the 1999 and 2018 classifications respectively. Exclusion criteria related to coexisting inflammatory or infectious diseases (e.g. malignancy, coronary heart disease or hepatitis); adjustment in diet or glycaemic control strategy; severe diabetic complications; pregnancy or lactation; allergies to amoxicillin or metronidazole; periodontal treatment or antibiotics within 3 months prior; smoking and alcohol abuse. The primary clinical outcome was a change in HbA1c. Secondary outcomes included the effect on periodontal parameters and haematological markers of inflammation.

Periodontal parameters measured were probing depth (PD), bleeding index (BI), Plaque index (PI), periodontally inflamed surface area (PISA), and clinical attachment level (CAL). Haematological parameters were glycated haemoglobin (HbA1c), fasting blood glucose (FBG), neutrophil-to-lymphocyte ratio (NLR), and white blood cell (WBC) count. For data analysis, poorly controlled T2DM was defined as baseline HbA1c > 7.5%. Statistical significance was defined as p < 0.05. Analysis within and between the two groups was analysed with Student's t-tests when data followed a normal distribution and the Mann-Whitney U test for non-normally distributed data. Chi-square testing was used to compare categorical variables. Uni- and multivariable binary logistic regression was employed to analyze the effectors related to HbA1c decrease. Intention-to-treat analysis was carried out for all enroled participants.

49 participants were enroled in the study; 23 were assigned to the SRP-only group and 26 to the SRP + antibiotics group. Nine participants were lost to follow-up. HbA1c levels decreased significantly after treatment in both the SRP group (7.6 ± 0.98% vs. 7.22 ± 0.88%, p = 0.001) and the SRP + antibiotics group (7.95 ± 1.23% vs 7.42 ± 1.14%, p = 0.004). Following multivariable regression analysis, female sex, adjunctive antibiotic use and high baseline HbA1c levels were associated with a greater decrease in HbA1c levels following periodontal therapy (OR = 9.358, 95%CI: 1.863-47.015; OR = 4.551, 95%CI: 1.012-20.463; OR = 7.162, 95% CI:1.359-37.753). Periodontal parameters significantly improved by a similar amount in both groups after treatment (p < 0.05). When the baseline PD was >6 mm, the SRP+ antibiotic group had more sites of improvement in PD than the SRP only group (698 sites vs 545 sites, p = 0.008).

SRP alone and SRP with adjunctive antibiotics both proved beneficial for improving glycaemic control and periodontal health at 3 months following periodontal therapy. Participants with baseline HbA1c > 7.5% were more likely to show an improvement in HbA1c when receiving adjunctive antibiotics. Adjunctive antibiotic use slightly increased the degree of improvement in probing depths for patients with pocket depths >6 mm and T2DM.