Mastication and risk for diabetes in a Japanese population: a cross-sectional study.

Background: Associations between mastication and insufficient nutrient intake, obesity, and glucose metabolism have been shown in previous studies. However, the association between mastication and diabetes has not been clarified. Our objective was to examine the association between mastication, namely masticatory performance or rate of eating, and diabetes in a population-based cohort.

Methods: We conducted a cross-sectional study of the association between mastication and diabetes in the Nagahama Prospective Cohort Study, an ongoing study which recruits citizens of Nagahama City in Shiga Prefecture, central Japan. 2,283 male and 4,544 female residents aged 40-74 years were enrolled from July 2009 to November 2010. Masticatory performance was evaluated by spectrophotometric measurement of color changes after masticating color-changeable chewing gum. Categorical rate of eating (fast, intermediate or slow) was self-assessed using a questionnaire.

Results: 177 males (7.7%) and 112 (2.4%) females were diagnosed with diabetes. We divided participants into four groups by quartile of masticatory performance, namely Q1 (lowest), 2, and 3 and 4 (highest). Compared to the lowest performance group, the multivariable adjusted odds ratio (OR) of diabetes was 0.91 (95% confidence interval (CI), 0.58-1.4) in Q2, 0.77 (95% CI, 0.48-1.2) in Q3, and 0.53 (95% CI, 0.31-0.90) in the highest group in males, and 1.2 (95% CI, 0.73-2.0), 0.95 (95% CI, 0.54-1.6) and 0.56 (95% CI, 0.30-1.0) in females. We also estimated ORs of diabetes by rate of eating. Compared to the fast eating group, ORs in males were 0.87 (95% CI, 0.61-1.2) in the intermediate group and 0.38 (95% CI, 0.16-0.91) in the slow group, and ORs in females were 0.92 (95% CI, 0.59-1.4) and 1.5 (95% CI, 0.73-3.0).

Conclusions: These findings support the hypothesis that higher masticatory performance and slow eating prevent the occurrence of diabetes.