Optimization of Salivary Electrochemical Analysis and its Collection Protocol in Type II Diabetes

In the last few decades, saliva due to its non-invasive nature has been highlighted as an important diagnostic biofluid and significant alteration in its composition has been reported with the progression of diabetes. We have investigated the best protocol for saliva collection, handling and processing to leverage its full potential for measuring salivary electrochemical parameters (SEPs) that serve as proxy indicators for fasting blood glucose levels (BGLs) in the body. SEPs such as pH, oxidation-reduction potential (ORP), conductivity and concentrations of Na⁺, K⁺ and Ca⁺⁺ ions were examined in a total of 60 age and sex matched (healthy and with diabetes) volunteers over three days (study 1) and during five different intervals in a day (study 2) and were subjected to statistical analysis. Effect of different age groups were also considered in study 2. None of the SEPs showed significant day-to-day variability (p > 0.05) in an individual belonging to either group. The variation among individuals was, however, higher in the diabetes group. The average SEP values were also distinctly different from the healthy baseline in the saliva collected after overnight fasting (P < 0.05). These findings imply that consumption of meals alters the salivary secretion and limits the use of the saliva-based studies to fasting intervals, which stands best for the salivary analysis during the diseased condition. Overall, we conclude that the SEPs collection protocol should be fixed to overnight fasting with 15 min of prior gargling.