Waist Size Predicts Diabetes Risk

Men Should Aim for Waist Size of 37 Inches or Less, Researchers Say

Reviewed by Michael W. Smith, MD on March 10, 2005
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March 10, 2005 - A man's waist size may say much more about his risk of developing type 2 diabetes than previously thought.

A new study suggests that a man's waist size is a better indicator of type 2 diabetes risk than other currently used measures, such as waist-to-hip ratio and body mass index (BMI, a measure of weight in relation to height).

Doctors use these measures to estimate a patient's risk of developing type 2 diabetes and advise them how to lower their risk, such as by losing weight and changing their diet.

Current cutoffs say that men should have a waist size of less than 40 inches to help prevent diseases such as heart disease, diabetes, and cancer.

But researchers say the cutoff for a man's waist size may need to be lowered to 37 inches. At that waist size researchers accurately identified more than 80% of the type 2 diabetes cases that developed in a large group of men followed over 13 years.

Waistline Reveals Diabetes Risk

In the study, researchers compared the effectiveness of BMI, waist size, and waist-to-hip ratio in predicting the risk of type 2 diabetes in more than 27,000 men. Results appear in the March issue of the American Journal of Clinical Nutrition.

All of the men had their BMI, waist size, and waist-to-hip measurements taken when the study began and were then followed for 13 years.

Men who had a waist size of 40 inches or more had the highest risk of type 2 diabetes. These men were 12 times more likely to develop the disease than those with a waist size of 34 inches or less.

Men with a BMI of 25 or more also were significantly more likely to develop type 2 diabetes.

Researchers say the results suggest that currently recommended cutoffs for estimating type 2 diabetes risk be lowered. Currently those cutoffs are 25 for BMI and 40 inches for a man's waist size.

But the study shows that lower cutoffs identified a significantly greater proportion of the type 2 diabetes cases.


Type 2 diabetes risk rose progressively as waist size climbed above 34 inches:

  • A waist size of 34 to 36 doubled diabetes risk.
  • A waist size of 36 to 38 inches nearly tripled the risk.
  • A waist size of 38 to 40 inches was associated with five times the risk.
  • A waist size of 40 to 62 inches was associated with 12 times the risk.
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SOURCE: Wang, Y. American Journal of Clinical Nutrition, March 2005; vol 81: pp 555-563.

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