Waist Size Again Shows Strong Link to Diabetes

Diabetes experts have long used both body mass index (BMI), a measure of weight related to height, and waist size to predict risk. Obese people, with a BMI of 30 or more, and non-obese individuals with large waists are considered at higher risk. Now, the new research finds that waist size alone predicts risk of diabetes, especially in women.

Researcher Claudia Langenberg, MD, PhD, of the Institute of Metabolic Science, Addenbrooke's Hospital, in Cambridge, England stated that, some overweight men and women with very large waists have the same risk of diabetes as obese people. In BMI terminology, "overweight" is a step below "obese."

"Our results now provide clear evidence that a simple measurement of waist circumference can identify overweight individuals (BMI 25-[29.9]) with a large waist, whose risk of future diabetes is equivalent to that of obese people." A large waist is 35 inches or more in a woman and 40 inches or more in a man.

Langenberg's team, the InterAct Consortium, re-evaluated data on more than 28,500 people. They lived in eight European countries. They were in the EPIC (European Prospective Investigation into Cancer and Nutrition) study. It looked at lifestyle and other factors, and chronic disease. They compared about 12,400 people with type 2 diabetes with about 16,100 people without. They looked at their waist and BMI data. Among the findings:

• Overweight women with a large waist (35-plus) and overweight men with a large waist (40-plus) had a 10-year incidence of diabetes similar to that of obese people.
• Higher waist size and higher BMI were each linked with higher diabetes risk.
• High waist size was a stronger risk factor for women than for men.
• Obese men with a large waist (40-plus) were 22 times more likely to develop diabetes than men with a low-normal BMI (18.5-22.4) and a smaller waist (less than 37 inches).
• Obese women with a large waist (35-plus) were nearly 32 times as likely to get diabetes than women of low-normal weight and a smaller waist (less than 31 inches).

Langenberg says, "BMI measures overall adiposity and gives no information about fat distribution."

Adiposity is a term used to represent fatness. Waist size reflects belly fat and fat around the internal organs, she says. That fat is strongly linked with type 2 diabetes.

Claudia Langenberg and colleagues conducted a collaborative re-analysis of data from the InterAct case-control study, ultimately finding a link between waist circumference and the risk of type 2 diabetes, independent of body mass index (BMI). After estimating the association of BMI and waist circumference with type 2 diabetes, they found that BMI and waist circumference were independently associated with the risk of type 2 diabetes but waist circumference was a stronger risk factor for women than men.

Overweight individuals account for a third of the US and UK adult population; these findings point towards the possible effectiveness of a targeted measurement of waist circumference to identify high-risk people that might benefit from individualized advice. The authors were quoted as saying, "Our results clearly show the value that measurement of [waist circumference] may have in identifying which people among the large population of overweight individuals are at highest risk of diabetes."

PLoS Medicine May 2012