Abstract
Context: The plausibility of a bidirectional link between periodontitis and type 2 diabetes has recently been acknowledged. However, little is known of the relationship between the two conditions at an earlier stage in the dysglycaemia continuum.
Objective: To describe the natural histories of periodontitis and dysglycaemia over 12 years through the third and fourth decades of life, to identify predictors of both conditions, and to explore the bidirectional relationship between them.
Methods: This study used data from the Dunedin Multidisciplinary Health and Development Study (DMHDS), a long-running prospective study of a birth cohort, and the utilisation of advanced statistical techniques to analyse these data. Both periodontal and glycated haemoglobin (HbA1c) data were gathered during the age-26, age-32 and age-38 assessments. Group-based trajectory analysis (GBTM) was used to assign Study members to trajectories of (a) periodontal experience (using mean % of sites with 4+mm attachment loss) and (b) dysglycaemia experience (using mean HbA1c). Generalisations of the model allowed the statistical linking of baseline characteristics to group membership probability, and identified effect modifiers associated with deviations from the group trajectory.
Results: Prevalence, extent and severity of periodontitis, and mean HbA1c, all increased with age, as did the prevalence of prediabetes, type 2 diabetes and dysglycaemia. Both periodontitis and dysglycaemia were highly prevalent by age 38, and health status at 26 predicted health status at 38. Four periodontal trajectory groups were identified: “Very low” 54.0%, “Low” 31.3%, “Medium” 11.3%, and “High” 3.5% (with mean % of sites with 4+mm attachment loss at age 38 of 0.0%, 2.9%, 19.6% and 64.4% respectively). Periodontal status, male sex, smoking, marijuana use, low SES, high plaque score and episodic use of dental services at age 26 were found to be predictors of poorer periodontal status 12 years later. Three HbA1c trajectory groups were identified: “Low” 11.0%; “Medium” 54.0%; and “High” 35.0% (with mean HbA1c at age 38 of 29.9 mmol/mol, 34.2 mmol/mol and 38.5 mmol/mol respectively). HbA1c levels, male sex, smoking, high waist circumference and high waist-height ratio at age 26 were predictors of dysglycaemia 12 years later. The influence of dysglycaemia at age 38 on the extent of periodontitis was found to be minimal and inconsistent, and periodontitis was found to have no influence on HbA1c at any age.
Conclusions: Trajectories of both periodontitis and HbA1c begin relatively early in adulthood with a greater risk of poor outcomes being established in the middle of the third decade of life. Periodontal and glycaemic health status at 38 were predicted by periodontal and glycaemic health status respectively at 26. Both conditions were highly prevalent by age 38. No relationship was found between periodontitis and dysglycaemia at this stage in the life course. The findings reinforce the importance of smoking and central adiposity as risk factors for poor health outcomes; they establish that health status at 26 has an influence 12 years later; and recommend that planning for the future burden of disease, early cardiometabolic screening, smoking reduction policies, and measures to tackle the obesogenic environment should be prioritised.