RESUMO
Background: The results of Shahroud Eye Cohort Study (ShECS) showed a high 5-year incidence of diabetes mellitus with female predominance in 40-64 years old Iranian population. The aim of this report was to decompose the observed sex differences in the incidence of diabetes. Methods: Sex-specific incidence rate of diabetes was calculated between the two phases of ShECS (2009-2014). The gap decomposition was done by the twofold Blinder-Oaxaca decomposition model. Results: The results showed that from the total gap (11.19%-15.55% = -4.36%) between the two sexes, 3.46% which forms 79.4% of the total gap is related to the difference in obesity in both genders. In contrast to obesity, age and overweigh status had a decreasing influence on gender inequality. Conclusions: Obesity of Iranian women compared with men is the most important reason for an increase in the incidence of diabetes in women.