Effect change of obesity on diabetes depending on measurement: self-reported body mass index from 2012 Community Health Survey vs. directly measured from the Korea National Health and Nutrition Examination Survey.

Objectives: Obesity is a well-recognized risk factor for type 2 diabetes mellitus (DM) among young and middle-aged adults in South Korea. To elaborate on the association between obesity and Diabetes mellitus (DM), subjective data from self-reporting survey or objective data from health examination is generally used. This study was conducted to validate the change of association from using these different measurements.

Methods: Community Health Survey data and Korea National Health and Nutrition Examination Survey data, as subjective and objective data respectively, were used. Population, resident in Seoul and over 45 aged, were selected for the study and the association between obesity and DM were defined by using multivariate logistic regression model.

Results: In subjective data, DM prevalence was 12.4% (male, 14.7; female, 10.6) and obesity prevalence was 26.0% (male, 29.2; female, 23.4). Whereas, in objective data, DM prevalence was 15.0% (male, 17.8; female, 12.9), and obese population was 32.4% (male, 34.4; female, 30.8). Based on the effect of obesity on DM prevalence from each data, using objective data increased the impact of obesity. Difference of relative risk of obesity between from subjective data and from objective was bigger in female than male and statistically significant.

Conclusions: The differences of association pattern between subjective and objective data were found, due to higher obesity prevalence in objective data, and discrepancies of socio-economic status. These discrepancies could be inevitable Therefore we have to face them proactively, and understand the different aspect of various variables from different measurement.