I’ve come to the conclusion that for me as a diabetic intense exercise (at high heart rates) is not good for my blood sugar control. Here’s a study of Type 1 Diabetics which shows the increase in blood sugar from intense exercise (Vinutha S, Paul F, Raymond D, et al. Effect of exercise intensity and blood glucose level on glucose requirements to maintain stable glycaemia during exercise in individuals with type 1 diabetes. Int J Pediatr Endocrinol. 2015;2015(Suppl 1):O39). The study looked at:
Nine young adults with T1D underwent euglycaemic clamps, whereby stable blood glucose levels between 4.5 to 6mmol/L were maintained during the study at basal insulin levels. Participants performed up to 40 minutes of exercise at four different exercise intensities (35%, 50%, 65% and 80% VO2peak) on four separate days following a randomised counterbalanced design. In a subsequent experiment, eight participants underwent either a euglycaemic or hyperglycaemic (9.5 – 10.5mmol/L) clamp at basal insulin levels, during which they performed 40 minutes of exercise at 50% VO2peak, on two separate days. In both studies, glucose infusion rates (GIR) to maintain stable glycaemia were measured during exercise, constant deuterated glucose was infused to determine glucose kinetics and blood samples were collected for the analysis of glucoregulatory hormones.
The result was:
The average GIR to maintain euglycaemia during exercise was 2.0±0.9, 4.0±1.5, and 4.1±1.7g/h (mean±SEM) at 35%, 50% and 65% VO2peak, respectively. These GIRs were all significantly greater than that at 80% VO2peak where no glucose was required (p<0.05). Exercise at 80% VO2peak was associated with a significant rise in catecholamine levels and endogenous glucose production (p<0.05). The average GIR to maintain stable glycaemia during exercise performed during the second experiment at 50% VO2peak was similar at euglycaemia (4.9±2.1g/h) and hyperglycaemia (5.5±2.5g/h; p>0.05).