209 - IDENTIFICATION OF OXYGEN-18 ISOTOPE OF BREATH CARBON DIOXIDE AS A NON-INVASIVE MARKER TO DISTINGUISH TYPE 1 AND TYPE 2 DIABETES
S. N. Bose National Centre For Basic Sciences. India.
Introduction: There is a pressing need to develop a new and an effective strategy for early detection of T1D and to precisely distinguish T1D from type 2 diabetes (T2D). The aim of the present study was to find out the potential link between the erythrocytes carbonic anhydrase (CA) activity and 18O-isotopic exchange of breath CO2 in T1D and T2D.
Methods: Fasting and post-dose breath and blood samples were collected simultaneously after ingestion of 75-gm normal glucose dissolved in 150-mL water. Blood samples were analysed to measure the CA activity. The breath samples were utilised to measure the carbon dioxide isotopes (12C16O16O, 13C16O16O and 12C16O18O) by a laser based high-precision carbon dioxide isotope analyzer.
Results: The CA activities are markedly altered during metabolism of T1D and T2D and this facilitates to oxygen-18 (18O) isotopic fractionations of breath CO2. In our observations, T1D exhibited considerable depletions of 18O-isotopes of CO2, whereas T2D manifested isotopic enrichments of 18O in breath CO2, thus unveiling a missing link of breath18O-isotopic fractionations in T1D and T2D. The optimal diagnostic cut-off points were determined to be δDOB18O‰ = 2.1‰ and ΔCA = 3.15 U/min/mL for screening T1D and T2D individuals.
Conclusions: Our findings suggest the changes in erythrocytes CA activities may be the initial step of altered metabolism of T1D and T2D, and breath 18O-isotope regulated by the CA activity is a potential diagnostic biomarker that can selectively and precisely distinguish T1D from T2D and thus may open a potential unifying strategy for treating these diseases.
