Comparison of [3,4-¹³C₂]glucose to [6,6- ²H₂]glucose as a tracer for glucose turnover by nuclear magnetic resonance

A recently introduced tracer, [3,4-¹³C₂]glucose, was compared to the widely used tracer, [6,6-²H₂]glucose, for measurement of whole-body glucose turnover. The rate of glucose production (GP) was measured in rats after primed infusions of [3,4-¹³C ₂]glucose, [6,6-²H₂]glucose, or both tracers simultaneously followed by a constant infusion of tracer(s) over 90 min. Blood glucose was purified and converted into monoacetone glucose for analysis by ¹³C NMR (for [3,4-¹³C₂]glucose) or ¹H and ²H NMR (for [6,6-²H₂]glucose) . The values of GP measured during infusion of each single tracer were not significantly different. In rats infused with both tracers simultaneously, GP was identical as reported by each tracer, 42 ± 4 μmol/kg/min. Since ²H and ¹³C enrichment in glucose is typically much less than 2% for in vivo studies, [3,4-¹³C₂]glucose does not interfere with measurements of ¹³C or ²H enrichment patterns and therefore is valuable when multiple metabolic pathways are being evaluated simultaneously.