Reduction in incidence of type 2 diabetes by lifestyle intervention in a middle eastern community

Background: Very few studies have used community-based interventions for primary prevention of Type 2 diabetes, and the direct effect of such interventions on diabetes incidence is relatively unknown.

Purpose: This study aims to assess the effect of lifestyle modification on risk factors for noncommunicable diseases (NCDs) and the development of Type 2 diabetes at the community level.

Design: A cluster-controlled trial was conducted.

Setting/participants: In all, 3098 and 5114 individuals in intervention and control groups, respectively (mean age=43 years), recruited from District 13 of Tehran, Iran, participated in the baseline examination in 1999-2001. Among these individuals, a total of 1754 and 2993 individuals in the intervention and control groups, respectively (58%), completed a follow-up examination in 2002-2005.

Intervention: The study intervention involved improvement in diet, increase in the level of physical activity, and reduction in cigarette smoking through educational interviews, lectures, and publications.

Main outcome measures: Incident Type 2 diabetes was measured by fasting plasma glucose (FPG) and 2-hour plasma glucose (2hPG) and change in NCD risk factors.

Results: The mean follow-up time was 3.6 years. The incidence of diabetes in the control and intervention groups was 12.2 and 8.2 per 1000 person-years, respectively, with a relative risk reduction of 65% (95% CI=30%, 83%, p<0.003). The adjusted difference in mean change of risk factors between the intervention and control groups was significant for weight (-0.5 kg in men); BMI (-0.18 kg/m(2) in men); waist circumference (-1.0 cm in women); systolic and diastolic blood pressure (-1.1 and -0.6 mmHg, respectively, in women); FPG (-2.1 and -2.3 mg/dL in men and women); 2hPG (-4.6 mg/dL in women); total cholesterol (-2.8 mg/dL in women); triglycerides (-7.6 and -5.2 mg/dL in men and women); and high-density lipoprotein cholesterol (1.1 mg/dL in women; all p<0.05).

Conclusions: Lifestyle intervention resulted in a significant decrease in the incidence of Type 2 diabetes and better control of NCD risk factors in a population-based setting. ISRCTN TRIAL REGISTRATION #: ISRCTN52588395.