Abstract Aim To analyse if body mass index (BMI) could be used as a fast proxy indicator of poor oral hygiene habits (POHH) among the adult population with diabetes mellitus. Methods Adults, aged 25-74, from the Slovenian 2016 nationwide cross-sectional survey based on the Countrywide Integrated Non-Communicable Disease Intervention (CINDI) Health Monitor methodology, who reported being diabetic, were included in the study (n=560). We assessed the relationship between POHH and BMI, adjusted to confounders, using multiple binary logistic regression. Results In the total sample, the POHH prevalence was 50.9%. Taking into account BMI, POHH prevalence in participants with normal BMI values was only 37.8%, in the overweight group it was 1.22-times higher (46.0%), while in the obese group it was 1.63-times higher (61.6%) (p<0.001). Also, the odds for POHH were 2.64-times higher in the obese group in comparison to the normal BMI group (95% CI: 1.55-4.51; p<0.001). After adjustment for confounders, this OR decreased only moderately (OR=2.45; 95% CI: 1.35-4.44; p=0.003). Conclusions BMI could be used as a readily assessable, fast, simple, and cheap tool indicating higher odds for having POHH among the diabetic population. By defining the high-risk group it could be easier for physicians and dentists to take further referrals and actions for promoting oral health in this group. The suggested tool can save time and could have an important positive impact on the quality of life of diabetics, as well as on health expenditures.