Monitoring circulating glucose responses before and following exercise, particularly high intensity exercise (HIIE), is essential to ensure safety and effectiveness of exercise interventions in people with type 2 diabetes (T2D). Despite the widespread monitoring of blood glucose in clinical and exercise settings, there remains inconsistency in the blood matrix used. Studies variably reporting glucose concentrations in whole blood (WB), plasma, or serum, which may provide different results. We tested the hypothesis that circulating glucose responses to acute HIIE will vary when measured in different blood matrices and that the effect will be greater in people with T2D, compared to people without T2D.

Thirty-three middle age and older adults without major diagnosed conditions (45 – 84 years, 24 females/nine males) and 18 adults with T2D (40 - 76 years, 8 females/10 males) completed a single acute high intensity interval exercise session (HIIE) (4 x 4 mins at 90 – 95% Heart Rate Reserve). Blood glucose levels were measured using an automated analyser (YSI 2300 STAT Plus Glucose Lactate Analyzer) in serum, plasma and WB at baseline and immediately, 30 min, 1 h, 2 h and 3 h post-HIIE.

Patients with T2D had higher circulating glucose levels, compared to people without T2D (~2 mmol/L, p<0.05)) at baseline and at all time-points post exercise, independent of the blood matrix measured (WB, plasma or serum). Yet, the change in glucose levels following exercise was similar between people with and without T2D (main effect for time, p<0.0001), and similar pattern in all blood matrices (p>0.05).

Circulating glucose response to acute exercise is not affected by the blood matrix it was measured in for people with and without T2D. Yet, as the absolute values vary between blood matrices, particularly WB, compared to serum and plasma, it is important to report the blood matrix used.