Impact of periodontitis on diabetic complications

Background + Aims

• Diabetic nephropathy (kidney damage caused by diabetes) is a leading cause of end-stage kidney disease (ESKD) and dialysis.
• Periodontitis (chronic gum inflammation) shares a bidirectional link with type 2 diabetes mellitus (T2DM) and is thought to raise systemic inflammatory markers (e.g. CRP, TNF-α) that can accelerate kidney decline.
• Whether regular periodontal care actually reduces the risk of needing dialysis had not been directly tested.
• This study aimed to:
  • Assess whether dental attendance with periodontal care is associated with a lower risk of dialysis initiation in adults with T2D.

Materials + Methods

• Retrospective cohort study using the Japan Medical Data Center (JMDC) nationwide claims database (medical, dental and health-check data), Jan 2015 – Aug 2022.

  • 99,273 adults aged 40–74 with T2DM

    • Mean age 54.4 years

    • 71.9% male

    • Median follow-up 3.62 years.

• Exposure (1-year window after inclusion), 4 groups:
  • No dental attendance (49.5%)
  • Dental visit without periodontal care (7.2%)
  • Periodontal care ≥1×/year (21.8%)
  • Periodontal care ≥1×/6 months (21.5%)
  • NB: Periodontal care defined as periodontal exam, scaling, root planing, pocket curettage, periodontal surgery or antibiotic pocket application.
• Outcome: dialysis initiation identified via severe CKD combined with dialysis procedures (haemodialysis or peritoneal dialysis).
• Cox proportional hazards models adjusted for 17 covariates (age, sex, insurance type, Charlson Comorbidity Index, diabetes treatment intensity, HbA1c, hypertension, hyperlipidaemia, urine protein, smoking, alcohol, physical activity, chewing difficulty, BMI, diabetes duration).
• Further analyses: accelerated failure time model, inverse probability weighting (IPW — a method that re-weights participants so exposure groups look similar on measured factors), multiple imputation for missing data, and E-values (a measure of how strong an unmeasured confounder would need to be to explain away the finding). A 2-year exposure analysis (n = 81,785) was also performed.

Results

• Overall dialysis incidence: 0.92 per 1,000 person-years.

• 1-year exposure (adjusted HR vs no attendance):

  • Dental visit without periodontal care: 0.93 (95% CI 0.63–1.37) – not significant

  • Periodontal care ≥1×/year: 0.68 (0.51–0.91), p < 0.05 – 32% relative risk reduction (RRR)

  • Periodontal care ≥1×/6 months: 0.56 (0.41–0.77), p < 0.001 – 44% RRR
• 2-year exposure (adjusted HR):
  • Care in either year: 0.62 (0.45–0.85) – 38% RRR
  • Care in both years: 0.53 (0.38–0.74) – 47% RRR
•  Sensitivity analyses (IPW Cox, binary exposure): HR 0.63 (0.50–0.80) at 1 year and 0.58 (0.45–0.74) at 2 years – consistent with the primary results.
• E-values ranged 2.30–3.18, meaning an unmeasured confounder would need a fairly strong association with both exposure and outcome to explain away the result.

Limitations

• Observational design – shows association, not causation.

• JMDC covers only employer-sponsored insurance (mainly employees of large firms and dependents), so generalisability to older adults, self-employed people or those in poverty is limited.

• Presence or severity of periodontal disease itself was not captured and specific periodontal procedures could not be analysed separately.

• Health behaviours (smoking, activity) were self-reported and crudely categorised.

• Socioeconomic status was unavailable — residual confounding is possible.

• Adherence to care may change over time; time-varying confounding not modelled (intention-to-treat approach).

• Findings apply to middle-aged Japanese adults with T2DM and may not extend to other populations or diabetes stages.

Conclusion

• Routine periodontal care (even at an intensity of x1 or x2/year) is associated with a substantially lower risk of progressing to dialysis in people with type 2 diabetes, and more frequent visits show a stronger association.
• Since more than half of the T2DM cohort received no periodontal care, the findings support integrating regular periodontal assessment and treatment into standard diabetes management and strengthening collaboration between medical and dental teams.
• Randomised trials are still needed to establish causality, but the results reinforce that oral health is a modifiable component of diabetes complication prevention.