Scientists believe testing for levels of the protein - RBP4 - may help identify those at risk of diabetes before symptoms become apparent, BBC reports.
Prescribing drugs to cut RBP4 levels may help stop the disease in its tracks.
The study was spearheaded by Beth Israel Deaconess Medical Center and published in the New England Journal of Medicine.
The importance of identifying the threat of diabetes is crucial to give patients the opportunity to take preventive measures.
Research Professor Barbara Kahn said: "Collectively, these findings tell us that RBP4 is a useful marker for therapeutic improvement and that this protein could play a causal role in insulin resistance in humans, just as our lab previously showed in mice.
"These findings could help clinicians to better manage this growing epidemic."
Dr Iain Frame, research manager at the charity Diabetes UK, said: "The causes of type 2 diabetes are very complex and still not fully understood.
"This research could offer a new line of enquiry which could help to understand the condition and help to produce new ways of battling its effects."
