Key Points
- To evaluate the effects of acute hyperglycemia on myocardial glucose extraction, oxidation, and downstream metabolic pathways in healthy individuals.
- Assessed seven healthy male subjects (age 24 ± 4 years) across a baseline control period and two 1-hour hyperglycemic clamp stages.
- Infused [6-14C]glucose and [U-13C]lactate isotope tracers to quantify myocardial glucose extraction, 14CO2 oxidation, and lactate release across arterial glucose levels of 4.95 ± 0.29, 8.33 ± 0.31, and 10.84 ± 0.60 μmol/ml.
- Myocardial glucose extraction increased from 0.15 ± 0.13 μmol/ml at baseline to 0.28 ± 0.12 μmol/ml at clamp level 1 (P < 0.02) and 0.54 ± 0.14 μmol/ml at clamp level 2 (P < 0.005).
- Immediate oxidation of exogenous glucose increased from 9 ± 10% during control to 32 ± 10% during level 2 hyperglycemia, while the proportion of released lactate derived from exogenous glucose rose from 40 ± 30% to 97 ± 37% (P < 0.005).
- Despite increases in oxidation and lactate conversion, an estimated 57% of extracted glucose is stored as myocardial glycogen.
Structured PICO
Does acute hyperglycemia alter myocardial glucose extraction and metabolism in healthy male subjects?
PPopulation7 healthy male subjects, mean age 24 +/- 4 years.
IInterventionAcute hyperglycemia induced via a clamp technique for 1 hour at two levels (mean arterial glucose 8.33 +/- 0.31 and 10.84 +/- 0.60 mumols/ml) with [6-14C]glucose and [U-13C]lactate tracer infusion.
CComparatorBaseline normoglycemic control state (mean arterial glucose 4.95 +/- 0.29 mumols/ml) in the same subjects.
OOutcomeMyocardial glucose extraction and metabolism (oxidation and lactate release).surrogate
Acute short-term hyperglycemia significantly enhances myocardial glucose extraction in healthy humans, with the majority of the excess extracted glucose likely stored as glycogen.