Trends in the prevalence of diabetes and impaired fasting glucose in association with obesity in Iran: 2005–2011

Abstract

To estimate the prevalence and trends of diabetes mellitus (DM) and impaired fasting glucose (IFG), 2005-2011, and to determine the contribution of obesity to DM prevalence. Data from Surveillance of Risk Factors of Non-communicable Diseases (SuRFNCD) conducted in 2005, 2007, and 2011 were gathered. DM was defined as presence of self-reported previous diagnosis or a fasting plasma glucose (FPG)≥7 mmol/L. IFG was diagnosed with FPG levels between 5.6 and 6.9 mmol/L. Prevalence rates for 2011 and trends for 2005-2011 were determined by extrapolating survey results to Iran's adult population. Population attributable fraction (PAF) of obesity was also calculated. In 2011, IFG and total DM prevalence rates were 14.60% (95%CI: 12.41-16.78) and 11.37% (95%CI: 9.86-12.89) among 25-70 years, respectively. DM was more common in older age (p < 0.0001), in women (p = 0.0216), and in urban-dwellers (p = 0.0001). In 2005-2011, trend analysis revealed a 35.1% increase in DM prevalence (OR: 1.04, 95%CI: 1.01-1.07, p = 0.011); albeit, IFG prevalence remained relatively unchanged (OR: 0.98, 95%CI: 0.95-1.00, p = 0.167). In this period, DM awareness improved; undiagnosed DM prevalence decreased from 45.7% to 24.7% (p < 0.001). PAF analysis demonstrated that 33.78%, 10.25%, and 30.56% of the prevalent DM can be attributed to overweight (BMI≥25kg/m(2)), general obesity (BMI≥30 kg/m(2)), and central obesity (waist circumference≥90 cm), respectively. Additionally, the DM increase rate in 2005-2011, was 20 times higher in morbidly obese compared with lean individuals. More than four million Iranian adults have DM which has increased by 35% over the past seven years, owing in large part, to expanding obesity epidemic.