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23-05-2010 | Diabetes | Article

Obesity increases risk for Type 2 diabetes more than seven fold


Free abstract

MedWire News: Results from a meta-analysis suggest that the presence of obesity increases the risk for developing Type 2 diabetes more than seven fold.

Researchers also found that overweight individuals had an almost three-fold increased risk for diabetes compared with normal weight individuals.

Obesity has been associated with an increased risk for Type 2 diabetes in many studies, but the exact magnitude of the association is uncertain.

In this study, Asnawi Abdullah (Monash University, Melbourne, Australia) and colleagues analyzed 18 prospective cohort studies including 590,251 people to assess the amplitude of the impact of obesity (body mass index [BMI]=30 kg/m2 or above) or overweight (BMI=25–30 kg/m2) on risk for Type 2 diabetes.

The participants were aged 18–80 years and were followed up for 2–27 years (median 9 years).

Writing in the journal Diabetes Research and Clinical Practice, the team reports that 15,771 cases of Type 2 diabetes were diagnosed over 5,480,996 person years of follow-up. This translated to an incidence rate of 2.9 per 1000 person years.

Overall, the pooled results from all 18 studies showed that obese and overweight individuals were 7.19 and 2.99 times, respectively, more likely to develop diabetes than normal weight (BMI=18.5–25 kg/m2) individuals.

However, to reduce heterogeneity, the analysis was carried out again including only studies with 400 cases of diabetes or more and factors such as age, family history of Type 2 diabetes, and physical activity were adjusted for. This resulted in a relative risk for developing Type 2 diabetes of 7.28 and 2.92 for obese and overweight individuals, respectively, compared with people of normal weight.

“There is a clear risk associated with both overweight and obesity that demonstrates the importance of preventing population-wide increases in body weight,” write Abdullah et al.

They conclude: “In order to derive a reliable and consistent estimate of the health risks associated with increasing weight we recommend the development of guidelines for the measurement and conduct of future cohort studies analyzing the relationship between overweight and obesity and diabetes.”

MedWire ( is an independent clinical news service provided by Current Medicine Group, a trading division of Springer Healthcare Limited. © Springer Healthcare Ltd; 2010

By Helen Albert