Doctors found that every five percent increase in liver fat was linked with a 27 percent jump in risk of developing the condition.
The study of more than 32,000 people in the UK Biobank also discovered those with a smaller pancreas were at greater risk.
Experts said it provided the first evidence that these factors can directly influence risk of Type 2 diabetes – and for some people, their genetics will place them in more danger than others.
Dr Hanieh Yaghootkar, a Diabetes UK RD Lawrence Fellow at Brunel University, said: “People with Type 2 diabetes usually have excess fat in their liver and pancreas, the two key organs in the maintenance of the normal level of blood sugar.
“We provided evidence for a causal role of liver fat in Type 2 diabetes risk.”
A healthy liver should contain little or no fat. People who are overweight are more likely to suffer from non-alcoholic fatty liver disease (NAFLD), which occurs when fat builds up in the organ.
Up to a third of people in the UK are thought to be in the early stages of NAFLD.
Having a smaller pancreas was also found to have a direct role, but no link with either liver or pancreas fat levels or size was found for Type 1 diabetes.
It is hoped that in future people will be genetically screened and those with a smaller pancreas alerted.
Dr Lucy Chambers, at Diabetes UK, said: “This research offers new insights into the causes of Type 2 diabetes that, as we move towards an era of personalised medicine, could in future help us to improve the way we predict, prevent and treat the condition.”
The findings were published in the journal Diabetes Care.
HORMONE ADDS TO INSULIN WEAPONRY
DIABETES scientists have found a hormone that works when insulin does not.
They say FGF1 uses different signalling to regulate blood-sugar in Type 2 patients, as insulin should. Dr Gencer
Sancar, at California’s Salk Institute, told Cell Metabolism journal: “With a different signalling cascade, if one is not working, the other can.”
FGF1 may also reverse the risk for those with prediabetes.