in blood

A two-way repeated-measure analysis of variance (ANOVA) was used to determine if there were statistically significant differences in blood metabolites, metabolic rate and rates of substrate utilization between the insulin and control trials, and over time.

This higher level of insulin in the INS trial promoted a fall in blood glucose from 11.2 [+ or -] 0.6 to 5.6 [+ or -] 0.1mmol/l after 4h rest in the INS trial, which was lower (P < 0.0001) compared with the fall in the CON trial (from 11.5 [+ or -] 0.7 to 8.5 [+ or -] 0.6 mmol/l, Figure 1(b)).

During exercise, there was a small but significant increase (P <0.01) in blood glucose in the INS trial (from 5.6 [+ or -] 0.1 mmol/l immediately before commencing exercise to 6.3 [+ or -] 0.03 mmol/l at 30 min of exercise) (Figure 1(b)).

Moreover, since the liver is sensitive to circulating insulin concentrations, the peripheral levels of which were similar between trials, the liver was not likely responsible for this increase in blood glucose.

As a result, previous studies with both mild [13] and high [14, 17] pre-exercise hyperglycaemia have shown reductions in blood glucose during exercise.