Breathalyzers to detect alcohol intoxication have existed for years, as the relationship between blood-alcohol content and alcohol in the breath is well understood. The same principles may soon be applied to diabetes screening. A team of researchers from Oxford University have succeeded in building a device that can flag patients as diabetic without the need for a blood test.

Right now, the only way to determine if someone is diabetic is to take some blood and check the levels of sugar through various methods. However, diabetes, the inability for the body to process sugar, comes with a number of metabolic quirks that can make it detectable in other ways.

The device developed at Oxford is looking for acetone in the patient’s breath. You probably know that as a volatile solvent, and it is. But it’s also produced as a consequence of regular human metabolism. Because diabetes sufferers are lacking in insulin, that throws much of their metabolism out of whack.

The condition that’s actually being tested for here is ketoacidosis, which is a condition associated with high concentration in the body of molecules called ketones — acetone, of course, is a ketone. In diabetic ketoacidosis, the lack of insulin means you can’t absorb glucose in the blood stream. This causes a cascade of metabolic failures that ends in a high concentration of ketones like acetoacetic acid in the blood. The acetoacetic acid in the bloodstream breaks down into acetone and carbon dioxide, and can be transferred to your breath via the lungs, just like alcohol in the bloodstream. That’s why someone with uncontrolled diabetes can sometimes have “fruity-smelling” breath.

The prototype breathalyzer from Oxford takes a sample of the patient’s breath and releases it into an optical cavity. A near-infrared laser is used to calculate the concentration of acetone in the person’s breath. If it’s beyond a certain level, that’s a strong indication of diabetes. In lab tests on human test subjects, the scanner was able to match the results obtained using much more expensive and time-consuming mass spectrometry.

The scanner is considerably smaller (see above) and cheaper than a mass spec instrument. With additional testing, researchers hope this simple test could help catch diabetes earlier. Diabetics would still need to track their blood glucose levels with an old-fashioned finger prick, but a separate team at Cambridge is working on a breathalyzer test for that too. Rather than tracking acetone in the breath, it watches for a molecule called isoprene.