The study, published in the Journal of Endocrinology, found diabetes in obese mice requires a hormone known as MSH, made by the POMC gene that is found in both mice and humans.
Scientists at the Eleanor Roosevelt Institute at the University of Denver, found obese mice without the MSH hormone were obese but did not develop diabetes.
Administration of the MSH hormone to these MSH-less mice increased resistance to insulin and directly affected blood sugar levels.
"Our findings show that obese people with high levels of the hormone MSH may be more likely to be diabetic than obese people with low levels of the MSH hormone," the study's lead author, Miles B. Brennan, said in a statement.
Preventive treatments, such as testing the MSH hormone levels in obese individuals and then administering a medication if the levels are too high, are currently being studied, Brennan said.
Type 2 diabetes, usually occurs in adults, when the body either doesn't make enough insulin or becomes resistant to insulin.