Trends of diabetes according to body mass index levels in Iran: Results of the national Surveys of Risk Factors of Non-Communicable Diseases (1999-2007)

Aims The prevalence of diabetes is increasing dramatically worldwide. Less is known about whether this trend is similar among obese and lean individuals.Methods We analysed the data sets of three cross-sectional national surveys in adults aged 25-64 years: the National Health Survey-1999 (n = 21 576), and the national Surveys of Risk Factors of Non-Communicable Diseases (SuRFNCD)-2005 (n = 70 981) and SuRFNCD-2007 (n = 4233). Diagnosed diabetes was ascertained, and height and weight were measured in all surveys. In SuRFNCD-2005 and SuRFNCD-2007, fasting plasma glucose was used to identify subjects with newly diagnosed diabetes (≥ 7 mmol/l) and impaired fasting glucose (5.6 -6.9 mmol/l) among individuals not reporting diabetes.Results The prevalence of diagnosed diabetes (after adjustment for age, sex and residential area) was 2.5, 4.0 and 4.6% in 1999, 2005 and 2007, respectively. The total prevalence of diabetes increased from 7.7% in 2005 to 8.7% in 2007, about half of which was attributed to newly diagnosed disease (in both surveys). The prevalence of diabetes increased in all categories of obesity, with the most evident trend being among subjects with body mass index < 25 kg/m².Conclusions The prevalence of diabetes among Iranian adults has increased more than 1.8-fold in a period of only 8 years since 1999. This is the first report from Iran, and urgent measures need to be taken in order to prevent the progression and worsening of the problem and emergence of its undesired consequences.