Prior exercise alters the difference between arterialised and venous glycaemia: implications for blood sampling procedures

Oral glucose tolerance and insulin sensitivity are common measures, but are determined using various blood sampling methods, employed under many different experimental conditions. This study established whether measures of oral glucose tolerance and oral glucose-derived insulin sensitivity (ISI) differ when calculated from venous versus arterialised blood. Critically, we also established whether any differences between sampling methods are consistent across distinct metabolic conditions (after rest versus after exercise). Ten healthy men completed two trials in a randomised order, each consisting of a 120-minute oral glucose tolerance test (OGTT), either at rest or post-exercise. Blood was sampled simultaneously from a heated hand (arterialised) and an antecubital vein of the contralateral arm (venous). Under both conditions, glucose time-averaged area under the curve was greater from arterialised compared to venous plasma but importantly, this difference was larger after rest relative to after exercise (0.99 ± 0.46 versus 0.56 ± 0.24 mmolL-1 respectively; p < 0.01). OGTT-derived ISIMatsuda and ISICederholm were lower when calculated from arterialised relative to venous plasma and the arterialised-venous difference was greater after rest versus after exercise (ISIMatsuda: 1.97 ± 0.81 versus 1.35 ± 0.57 au, respectively; ISICederholm : 14.76 ± 7.83 versus 8.70 ± 3.95 au, respectively; both p < 0.01). Venous blood provides lower postprandial glucose concentrations and higher estimates of insulin sensitivity, compared to arterialised blood. Most importantly, these differences between blood sampling methods are not consistent after rest versus post-exercise, preventing standardised venous-to-arterialised corrections from being readily applied. Registered under ClinicalTrials.gov Identifier no. NCT02852044.