Optometrists may be able to expand their scope of practice by testing to detect type 2 diabetes and prediabetes, according to Professor John Burd, chief science officer at Freedom Meditech.
The study, published in the Journal of Diabetes Science and Technology, found measurements from a lens autofluorescence test using a new scanning confocal biomicroscope, were effective in identifying diabetes when compared to current hemoglobin A1c and fasting plasma glucose tests.
Professor Burd said the test may benefit individuals with an aversion to blood draw and those that do not frequently visit their primary General Practitioner (GP). The lens autofluorescence test takes six seconds, is non-invasive and does not require fasting. In contrast, standard blood tests require blood draw and assay materials, and create biohazard waste.
Victorian optometrist and President of the Optometrists Association Australia, Andrew Harris, said the test may improve patient outcomes. “While the association between lens autoflourescence and diabetes has been known for many years this new tool could be useful for finding people with undiagnosed diabetes earlier.
“Optometrists often detect general health conditions in an eye examination and obviously any new equipment or technology to assist this needs to be used alongside the existing evidence base and in collaboration with a patient’s GP,” said Mr. Harris.
“If the test proves to be as accurate as reported, there may be potential for earlier detection by optometrists and reducing the number of people with undiagnosed diabetes, currently thought to be 50 per cent.”
Autofluorescence detects the presence of advanced glycation products, or AGEs, in the lens of the eye. AGEs are yellow-brown and fluorescent proteins that are modified when sugars are metabolised. In the crystalline lens of the eye, AGEs are long-lived and accumulate over time. Studies have shown that AGEs are correlated with uncontrolled glucose.
The researchers took measurements from 233 participants, 180 patients without diabetes and 53 patients with diabetes or prediabetes. Results showed the lens autofluorescence test detected type 2 diabetes with a sensitivity of 67 per cent and a specificity of 94 per cent. The hemoglobin A1C test displayed a sensitivity of 44 per cent and a specificity of 79 per cent. The fasting plasma glucose test displayed a sensitivity of 50 per cent and a specificity of 95 per cent in comparison.
Invaluable for Early Detection
Dr. Ben Ashby, an Associate Lecturer at University of New South Wales, said a noninvasive device of the type described in the paper would be invaluable for early detection of diabetes and may help reduce morbidity associated with the disease. He cautioned “a number of issues with the technology need to be addressed, including a sensitivity that would suggest 33 per cent of patients with diabetes screened by this method would be missed. This delay in the diagnosis of diabetes could result in deterioration of the patient’s health.
“The study also excludes subjects with cataracts and ocular surface disease which represents a significant proportion of those at risk of diabetes.
Furthermore the data shows that the test becomes increasingly insensitive in older patients who are also at greater risk of diabetes.” Dr. Ashby concluded, “the device is an interesting technology for non-invasive exclusion of diabetes that requires further development if it is to be embraced for screening of patients.”
The study was published in the Journal of Diabetes Science and Technology (Jan 2014). It was funded by, and used a ClearPath DS-120 Lens Fluorescence Biomicroscope developed by, Freedom Meditech.