Published in Nature Genetics, the paper examined the effect of a gene called KLF14. The researchers found that genetic variations that control KLF14 have little impact on overall weight but they have a marked impact on where in the body any excess fat is stored. In women, versions of the gene that are result in fat being preferentially deposited around the hips, rather than around the abdomen, provide protection against diabetes.
The different variations of KLF14 have an impact on the development of fat cells, and a striking effect on their size. In women carrying the version of the KLF14 gene that is associated with increased risk of diabetes, the individual fat cells are much larger and full of fat. This is likely to because there are fewer such cells in the first place, such that each cell ends up needing to take up more fat. This is known to result in inefficient, unhealthy fat cells that are more likely to contribute to diabetes.