Smoking modifies the effect of diabetes on severe tooth loss: Cross-sectional analysis of Hawai'i BRFSS data from 2012 to 2020.

Smoking and diabetes have detrimental effects on tooth loss, though few studies have examined their interaction. Using five waves of cross-sectional data from the state of Hawai'i in the United States, this study aimed to examine the interaction effects between smoking and diabetes on severe tooth loss (≥6) among adults, using a weighted logistic regression approach. In Hawai'i, the overall prevalence of severe tooth loss was 9.7%. Among never smokers, diabetes was associated with a 10.3% higher prevalence of severe tooth loss compared with those without diabetes. The differences due to diabetes were nearly doubled among former smokers (19%) and current smokers (16.2%). After adjusting for sociodemographic factors, the differences were smaller but still statistically significant, indicating the aggravating effect of smoking on tooth loss among those with diabetes. Awareness of the interaction between smoking and diabetes is crucial for the development of policies aimed at improving health equity.