Population-based incidence of Type 2 diabetes and its associated risk factors: results from a six-year cohort study in Iran.
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 >or= 20 years (mean age 42 +/- 13 years, 42% males), glucose tolerance test was performed at baseline in 1999-2001 and at two consecutive phases in 2001-2005 and 2005-2008. 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: 5.6-7.2) and incidence rate of 10.6 (9.2-12.1) 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 (1.1-1.3)], family history of diabetes [1.8 (1.3-2.5)], body mass index >or= 30 kg/m2 [2.3 (1.5-3.6)], abdominal obesity [1.9 (1.4-2.6)], high triglyceride [1.4 (1.1-1.9)], Isolated impaired fasting glucose (IFG) [7.4 (3.6-15.0)], Isolated impaired glucose tolerance (IGT) [5.9 (4.2-8.4)] and combined IFG and IGT [42.2 (23.8-74.9)].


CONCLUSIONS
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.
Harati
Hadi
H
Prevention of Metabolic Disorders Research Center, Research Institute for Endocrine Sciences, ShahId Beheshti University(M,C), Tehran, Iran. harati@endocrine.ac.ir
Hadaegh
Farzad
F
Saadat
Navid
N
Azizi
Fereidoun
F
D000328:Adult; D000368:Aged; D000886:Anthropometry; D015992:Body Mass Index; D015331:Cohort Studies; D003924:Diabetes Mellitus, Type 2 / Q000453:epidemiology*; D005260:Female; D006801:Humans; D015994:Incidence; D007492:Iran / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D011159:Population Surveillance; D012307:Risk Factors; D011795:Surveys and Questionnaires; D014505:Urban Population