Body mass index is a more powerful risk factor for diabetes than genetics

A person's Body Mass Index (BMI) is a more powerful predictor of whether they will develop diabetes than their genes, according to new research.

 
Researchers from the University of Cambridge studied 445,765 participants of the UK Biobank.

Inherited risk of diabetes was assessed using 6.9 million genes and the height and weight of participants were measured to calculate their BMI in kg/m2. Participants were divided into five groups according to genetic risk of diabetes. There were also divided into five groups according to BMI. 
 
Participants were followed-up until an average age of 65.2 years. During that period, 31,298 of the participants developed type 2 diabetes. 

The higher the BMI the higher the risk

Those in the highest BMI group (average 34.5 kg/m2) had an 11-fold increased risk of diabetes compared to participants in the lowest BMI group (average 21.7 kg/m2). The highest BMI group had a greater likelihood of developing diabetes than all other BMI groups, regardless of genetic risk.  

The investigators then used statistical methods to estimate whether the likelihood of diabetes in people with a high BMI would be even greater if they were overweight for a long period of time. They found that the duration of elevated BMI did not have an impact on the risk of diabetes. 

Lead researcher, Professor Brian 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.”

A vital risk factor

Professor Jeremy Pearson, our Associate Medical Director, said: "This important study of nearly half a million people shows that BMI is a more vital risk factor for type 2 diabetes than we previously realised. It highlights the need to regularly measure BMI and track blood sugar levels of people at high risk to bring them under their personal BMI threshold and into a healthy range. 

“When someone’s BMI goes above their personal threshold, blood sugar levels increase, triggering the onset of type 2 diabetes, which can lead to damaged blood vessels and increased risk of developing heart and circulatory diseases. If you are overweight, making small, long-term changes to your lifestyle such as reducing portion sizes and being more physically active can help lower your BMI, which is good for your heart and blood vessels.”

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