Only a quarter of GPs are routinely measuring abdominal obesity in patients, a new study by the charity Diabetes UK shows.
Fewer than one in four overweight and obese patients have had their waistlines measured by a family doctor, it found.
Research has shown that abdominal obesity can be a key indicator of future heart disease and type 2 diabetes.
Studies suggest that a waist circumference of more than 35in in women and 40in in men indicates a high risk of developing heart problems and diabetes.
But the lower measurements of 31.5in in women and 37in in men are also thought to lead to an increased risk.
Simon O'Neill, director of care, information and advocacy at Diabetes UK, said: "There is a worrying lack of awareness around the health implications of waist measurements.
"Up to 750,000 people in the UK have type 2 diabetes, but don't know it.
"By diagnosing the condition early, people reduce their chances of developing the serious complications of diabetes including heart disease, kidney problems and amputations."
The Shape of the Nations survey 2007 polled 11,000 people in 28 countries, including the UK.
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