Glycaemic status and periodontitis severity Among patients attending a South African tertiary oral health centre: a prospective cross-sectional study

Background Diabetes mellitus (DM) and periodontitis are chronic inflammatory conditions with a well-established bidirectional relationship. Given the strong association between these conditions, individuals with periodontitis may have an increased likelihood of dysglycaemia that has not previously been recognised. This study aimed to determine the prevalence of diabetes and prediabetes among patients with periodontitis and to examine the relationship between glycaemic status and periodontitis severity. Aim To determine the prevalence of DM and prediabetes among patients with periodontitis attending a tertiary oral health centre in South Africa and to examine the relationship between glycaemic status and periodontitis severity. Methods A prospective cross-sectional study was conducted among 73 adults diagnosed with periodontitis at the University of Pretoria Oral Health Centre. Participants underwent comprehensive periodontal assessment and HbA1c testing. Previously diagnosed diabetes was recorded from the medical history. Among participants without a previous diagnosis, HbA1c ≥ 6.5% was considered a diabetic-range result for study screening purposes and HbA1c 5.7%–6.4% was considered the prediabetic range. Exact 95% confidence intervals (CIs) were calculated for prevalence estimates. HbA1c distributions were compared by periodontitis stage using the Kruskal–Wallis test. An exploratory multivariable logistic regression examined factors associated with dysglycaemia (diabetes or prediabetes). Results Participants had a mean age of 50.7 years (SD 15.2); 47 (64.4%) were female. Generalised periodontitis was present in 69 (94.5%), with 46 (63.0%) classified as Stage 4 and 56 (76.7%) as Grade C. Thirteen participants had previously diagnosed diabetes. Among the 60 participants without a previous diagnosis, 6 (10.0%, 95% CI 3.8–20.5) had HbA1c values ≥6.5%, while 25 (41.7%, 95% CI 29.1–55.1) had HbA1c values of 5.7%–6.4%. Overall, 19/73 (26.0%) participants had either established diabetes or a diabetic-range HbA1c result, while 25/73 (34.2%) had HbA1c values in the prediabetic range. Median HbA1c was 5.7% (IQR 5.4%–6.1%). Stage 4 participants had a wider HbA1c range and a higher upper quartile than Stage 3 participants, but the difference was not statistically significant ( P = 0.423). In exploratory regression analysis, increasing age was associated with dysglycaemia (OR 1.08, 95% CI 1.04–1.13; P < 0.001), while sex and Stage 4 status were not significantly associated. Conclusion A substantial burden of dysglycaemia was identified among patients presenting with periodontitis, including diabetic-range HbA1c results among participants without previously diagnosed diabetes. These findings support consideration of appropriate glycaemic risk assessment and referral within periodontal care pathways. Larger multicentre studies, including periodontally healthy comparison groups, are required to further investigate this relationship and evaluate screening strategies.