Association between gestational diabetes mellitus and periodontal inflammation in a South African cohort

Objectives To investigate the association between gestational diabetes mellitus (GDM), periodontal status, and systemic inflammatory gene expression among pregnant women in South Africa. Materials and methods This case–control study included 105 pregnant women, comprising 52 women with GDM and 53 normoglycaemic controls. Participants were classified into four groups according to GDM and periodontal status. Periodontal assessment included probing depth (PD), clinical attachment level (CAL), and bleeding on probing (BOP). Peripheral blood expression of CRP, IL-6, TNF-α, MMP-8, and MMP-9 was assessed using quantitative real-time PCR and expressed as relative gene expression. Multivariable logistic regression was adjusted for maternal age, BMI, gestational age, parity, smoking status, ethnicity, and toothbrushing frequency. Results PD, CAL, and BOP differed significantly across the four groups (all p < 0.001), with the highest BOP observed in women with both GDM and periodontitis. By GDM status, BOP was significantly higher in women with GDM [median 32.5% (range 8–70) vs. 13.0% (range 1–38); p < 0.001], whereas PD and CAL did not differ significantly in unadjusted analyses. After adjustment, BOP, PD, and CAL were significantly associated with GDM. MMP-9 relative expression differed overall across the four groups ( p = 0.047), although adjusted post-hoc pairwise comparisons were not significant. IL-6 differed by GDM status in unadjusted analysis ( p = 0.039) but not after adjustment. Conclusion GDM was associated with greater periodontal inflammatory burden, particularly BOP. Systemic inflammatory gene-expression differences were less consistent and showed no independent associations with GDM after adjustment.