One of the problems with diabetes is that patients can develop autonomic neuropathy. This means that the nerves that control the automatic body systems — such as heart beats or digestion — become progressively impaired. The problem is that this can be difficult to detect before the impairment becomes severe and organ damage has already occurred. Researchers in Taiwan believe that they have found a way to diagnose this condition early, before the symptoms begin to show.

In a paper published in the journal Applied Optics, the scientists describe a head-worn pupillometer that measures the size of a patient’s pupils under various conditions. Starting with a darkened room, the device takes measurements of the patient’s eye under lights of four different colors at two different intensities. The size of the pupil and the speed of response to the light turn out to be an indicator of whether or not the patient has autonomic neuropathy. The pupil reaction is also an autonomic system, and so can serve as a early indicator of the condition. Comparing the results of tests of healthy subjects with those who have diabetes, the researchers found correlations that can be used to distinguish between the two groups.

More clinical research data will be needed in order for this method to prove useful, but it holds the promise of an inexpensive, lightweight, and automated system that could lead to the early diagnosis and treatment of diabetes and related conditions. The researchers hope that the device could be ready for widespread use by the end of the decade.