Population-based incidence of Type 2 diabetes and its associated risk factors: Results from a six-year cohort study in Iran

Abstract

Background. The Middle East is estimated to have the largest increase in prevalence of diabetes by 2030; yet there is lack of published data on the incidence of Type 2 diabetes in this region. This study aimed to estimate Type 2 diabetes incidence and its associated risk factors in an Iranian urban population. Methods. Among 3307 non-diabetics 20 years (mean age 42 13 years, 42% males), glucose tolerance test was performed at baseline in 19992001 and at two consecutive phases in 20012005 and 20052008. Diabetes and glucose tolerance status were defined according to the ADA 1997 criteria. Logistic regression was used to determine the independent variables associated with incident diabetes and their odds ratios (OR). Results. After median follow-up of 6 years, 237 new cases of diabetes were ascertained corresponding to an age and sex standardized cumulative incidence of 6.4% (95%CI: 5.67.2) and incidence rate of 10.6 (9.212.1) per 1000 person years. Besides classical diabetes risk factors, female sex and low education level significantly increased risk of diabetes in age adjusted models. In full model, the independent predictors were age [OR, 95%CI: 1.2 (1.11.3)], family history of diabetes [1.8 (1.32.5)], body mass index 30 kg/m2[2.3 (1.53.6)], abdominal obesity [1.9 (1.42.6)], high triglyceride [1.4 (1.11.9)], Isolated impaired fasting glucose (IFG) [7.4 (3.615.0)], Isolated impaired glucose tolerance (IGT) [5.9 (4.28.4)] and combined IFG and IGT [42.2 (23.874.9)]. Conclusion. More than 1% of the Iranian urban population older than 20 years develops Type 2 diabetes each year. Combination of IFG and IGT was the strongest predictor of incident diabetes among the modifiable risk factors. © 2009 Harati et al; licensee BioMed Central Ltd.