The test looks at levels of five amino acids in the blood.
Harvard researchers say it could spot the disease up to 10 years before the first symptoms occur. Catching Type Two diabetes early might help reduce the risk of complications such as heart disease, stroke, kidney failure blindness and amputation. Right now, doctors have little aside from keeping an eye on a person's weight and blood sugar to identify those at risk.
There's more on the experimental test in the journal "Nature Medicine".