The study published in the British Medical Journal was conducted by researchers in Sweden and compared girth with biological markers that predict insulin sensitivity.

"A waist circumference of less than 100cm (39.4 inches) excludes insulin resistance in both sexes," the study found.

Lead author of the study is Hans Wahrenberg, associate professor at Stockholm's Karolinska University hospital.

Diabetes

Diabetes is caused by a problem with insulin, a hormone that stimulates the body's cells into absorbing the energy source, glucose, from the blood.

"A waist circumference of less than 100cm excludes insulin resistance in both sexes"

Swedish study

Insulin deficiency can lead to heart and blood disorders that are responsible for an estimated 50% to 80% of the deaths that occur among diabetics.

People with severe forms of the disease can also suffer from blindness, loss of limbs and kidney failure.

Insulin resistance is the cause of so-called Type 2 diabetes, which accounts for about 90% of all cases of the disease and usually shows up in adults aged 40 and above.

In Type 2 diabetes, insulin is produced but at insufficient levels or does not work efficiently, either because it is defective in some way or the cells themselves have become resistant to it.

Incidence of Type 2 has rocketed alongside rates of obesity, triggered by consumption of sweet and fatty foods and a sedentary lifestyle.

Type 1 diabetes develops in early childhood, when the immune system destroys beta-cells and leaves the patient with a lifelong dependency on insulin injections.