Salivary testing for diabetes   (May 17, 2009)

An intriguing abstract was presented at the recent AACE meeting, titled Salivary biomarkers of type 2 diabetes: proteomic profiles for non-invasive diagnostics. The authors identified another way to look for cases of diabetes besides blood glucose testing.

The authors studied saliva from 40 people, 10 with type 2 diabetes (T2DM), 20 with impaired glucose tolerance (IGT), and 10 controls. They found that measurement of various proteins in these folks showed some differences in some of the proteins: of 487 proteins that they identified, 65 demonstrated a greater than 2-fold difference in abundance between control and T2DM samples, and not too surprisingly, the majority of the proteins that were more abundant in the diabetic individuals belong to pathways regulating metabolism and immune response. And the saliva of folks with IGT showed a trend for a similar increase in the proteins seen in the T2DM patients.

Fascinating. I've heard in the past of lots of ways to attempt to get a handle on the presence or absence of diabetes besides blood glucose and the associated lab test A1C. Among others that have been tried in the past, I remember mention of analysis of tears, and of earwax. But those methods involved obtaining the sample and then analyzing the sugar content of the sample, so the new report, measuring proteins in spit, is based on an entirely different concept.

The authors measured the proteins in only a few people, but presumably they will happily scale up their findings to hundreds or thousands of people sooner or later. Assuming the initial findings continue to hold up, and perhaps that they identify a few proteins that turn out to be excellent biomarkers for diabetes, they might just be on to something. At this stage, it seems more likely that the test would be used for screening for diabetes, rather than replacing BG measurements used in day-to-day control of diabetes.

Some other questions immediately come to mind: how much spit is needed to do the analysis? Should it be fasting saliva sample, or pre-washing the mouth with a large quantity of water or something else? Will the levels of the proteins be different in people with poorly-controlled diabetes compared to people with tightly-controlled diabetes? And how much does it cost to do the analysis at this time, and is likely to decrease if it becomes more widely used?

I look forward to hearing more about this concept.