Body mass index a bigger factor in type 2 diabetes than genetics

Over 225,000 people in Ireland have diabetes, most of whom have type 2 diabetes. A new study has found body mass index is a much bigger indicator of type 2 diabetes than genetics. File Picture.

Body mass index is a much bigger risk factor for type 2 diabetes than genetics, a new study of almost half a million people has suggested.

Most cases of the disease could either be prevented or reversed if someone's BMI was kept below their personal cut-off point at which abnormal blood sugar levels are triggered, an expert behind the study said.

Everyone had a different threshold at which they are at risk of becoming diabetic, explaining why some people with a healthy weight develop the condition and some who are overweight do not, Brian Ference, a Cambridge University professor said.

Professor Ference said study's findings could have "significant implications" for the approach to screening for, preventing, treating and even reversing the condition.

The study of 445,765 participants of the UK Biobank saw people divided into five groups according to genetic risk of diabetes and five groups according to BMI.

Just over half of the participants were women and the average age was 57. By the time they reached 65 years, 31,298 had developed type 2 diabetes.

Those in the highest BMI group had an 11-fold increased risk of diabetes compared to the lowest BMI group, researchers said, and a greater likelihood of developing diabetes than all other BMI groups, regardless of genetic risk.

Investigators also discovered that the length of time a person had a higher BMI did not have an impact on the risk of diabetes.

Prof Ference said most cases of diabetes could be prevented by keeping BMI below a person's threshold and researchers hoped to be able to estimate that soon.

The findings, presented at the European Society of Cardiology Congress, highlight the need to regularly measure BMI and track blood sugar levels of people at high risk, the British Heart Foundation said.

It is estimated that over 225,000 people are living with diabetes in Ireland. Most of these have type 2 diabetes.

A senior dietitian with Diabetes Ireland, Sinéad Powell, agreed there was a higher risk of getting type 2 diabetes linked to being overweight than to a person’s genes or family history.

“Approximately 65% of type 2 diabetes could be prevented or a diagnosis delayed by simple lifestyle measures aiming for weight loss especially around the abdominal area. This can be achieved with a healthy diet and avoiding sedentary behaviour,” she said.