Body mass index more of risk factor for diabetes than genetics, says study

● Being overweight even for a short time can increase the likelihood of disease

Body mass index (BMI) is a much more powerful risk factor for type two 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 cutoff point at which abnormal blood sugar levels are triggered, an expert behind the study said.

Everyone will have a different threshold that sees them at risk of becoming diabetic, explaining why some people with a healthy weight develop the condition and some who are overweight do not, the Cambridge University professor said.

Professor Brian Fer ence said the findings of the study 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.

Participants, just over half of whom were women, had an average age of 57 and were followed up until an average age of 65. During that period 31,298 of them developed type two diabetes.

Those in the highest B MI group had an 11-fold increased risk of diabetes compared to the lowest B MI group, researchers said, and a greater likelihood of developing diabetes than all other BMI groups, regardless of genetic risk. Investigators also discovered the length of time a person had a higher BMI did not have an impact on the risk of diabetes.

Prof Ference said: “This suggests that when people cross a certain BMI threshold, their chances of diabetes go up and stay at that same high-risk level regardless of how long they are overweight.”

Explaining further the significance of the study, he said: “You can prevent most cases of diabetes by keeping BMI below a person’s threshold.

“But it[ the study] also implies something that we haven’t focused on in the past and that is we can also prob - ably reverse most cases of diabetes if we lower somebody’s BMI aggressively below their BMI threshold relatively soon after they develop diabetes.

“I think the fact that B MI appears to have a threshold rather than a cumulative effect on the risk of diabetes really has potentially significant implications for how we think about changing screening, preventing, treating and reversing diabetes.”

He said work was ongoing to be able to allow researchers to estimate what someone’s threshold was and that he hoped for a breakthrough on that by the end of this year.