A study presented by Vishnupriya Rao Paturi, MD, PhD, FACE reported that identification of a large number of proteins in human saliva might help in the development of a noninvasive saliva test to diagnose diabetes and prediabetes. However, to better understand the findings more research has to be done.
Srinivasa R. Nagalla, MD, a member of Dr. Paturi’s team, told that we are trying to identify a way to detect prediabetes/diabetes noninvasively, using saliva as a noninvasive vehicle. We have sequenced the antisalivary proteomes in type 2 diabetes and identified all of the proteins in saliva, which is about 600 or so proteins, and then examined if they are different in controls vs [patients with] diabetes and prediabetes.
Several proteins were identified that are different in all 3 groups by the team.
The prospective observational study involved 40 subjects in whom saliva was analyzed for proteins. The cohort was divided into 4 groups of 10. One group had previously diagnosed type 2 diabetes and were receiving treatment, the second group had impaired glucose tolerance (IGT), and the third group had IGT with impaired fasting tolerance (IFG). The fourth group was a control group of clinically healthy individuals. Saliva was characterized using multidimensional liquid chromatography/tandem mass spectrometry.
The analysis revealed a total of 487 unique proteins, approximately 33% of which were previously unidentified in human saliva. Of these, 65 demonstrated a greater than 2-fold difference in abundance between control and type 2 diabetes samples, the team wrote in their abstract.
The majority of these proteins are involved in regulating metabolism and immune response. Several of the biomarkers in patients with type 2 diabetes were differentially abundant in the saliva of patients with IGT alone and IGT and IFG. The proteomes were independently validated using Western immunoblotting and enzyme-linked immunosorbent assay.
The researchers reported that the study points toward the development of a noninvasive dipstick test of saliva that will determine if a patient is prediabetic or diabetic. They presented a prototype device that resembled a tongue depressor.
Dr. Nagalla said: The majority of prediabetics are not diagnosed because [they don’t have] access to healthcare. Our main objective is to provide a very simple device, just like a pregnancy [test] . . . so that you don’t have to go get blood drawn to test for fasting plasma and glucose to know whether you’re diabetic or prediabetic. That’s the biggest hurdle we see in the diabetes area and [something we] would like to change to get more accessibility.
However, Harmeet Singh Narula, MD, FACP, FACE, assistant professor of medicine at Stony Brook University Medical Center in New York and judge of the poster session, told that there needs to be a better understanding of all these proteins, with one third of them having never been described in human saliva before. It’ll be at least 3 to 5 years before there is any replacement of the standard blood test. There needs to be a much larger, much more rigorous study to evaluate the reverse — the predictability of these patterns of protein expression.
Dr. Narula agreed: It’s too speculative to say if, over time, it could change diabetes therapy. It’s intriguing and interesting, . . . but it’s something we’d like to see in a larger group of people.