Combining High Intensity Exercise And Carb Intake in Type 1 Diabetes

Carbohydrate ingestion combined with short sprints before a moderate-intensity workout does not negatively affect patients with type 1 diabetes.

The consequence of long-interval, high-intensity exercise, defined as activity over 10 minutes at >80% peak rate of oxygen consumption, is different from moderate-intensity exercise in terms of glycemic effects in patients with type 1 diabetes. Intense exercise causes an elevation of glucose in comparison to a reduction associated with moderate-intensity exercise in individuals with type 1 diabetes who use insulin.

In high-intensity exercises, glucose utilization is lower than glucose production, initially. In a person without diabetes, this process leads to an increase in glucose and therefore a significant rise in insulin for 40–60 minutes to help restore glucose levels. In contrast, the absence of this response in an individual with type 1 diabetes causes continuous hyperglycemia.

A study was conducted to examine if a 10-second sprint, performed right before moderate-intensity exercise, would counteract the rapid hypoglycemia caused by moderate-intensity exercise in patients with type 1 diabetes. This study included seven male patients with type 1 diabetes and no other complications. Average HbA1c  level and age of the participants were 7.4 ± 0.7% and 21.6 ± 3.6 respectively. In order to test the effect of 10 second sprints, individuals in the study group performed a 10-s all-out sprint immediately before a 20-minute moderate-intensity cycling. This routine was performed once participants post-prandial glucose level was about 11mmol/l (198mg/dL)

The results of this study showed that 10-second sprinting right before a moderate intensity exercise did not lower glucose level (2.9 ± 0.4 mmol/l (52.2mgdL ± 7.2mg/dL)  in 20 min; p = 0.00; mean±SE). The conclusion indicates that for individuals with type 1 diabetes, 10-s sprints completed immediately preceding a moderate-intensity exercise, prevents glucose from falling during early recovery from moderate-intensity exercise.

Carbohydrate ingestion can lessen the hypoglycemia risk seen during moderate-intensity exercise. Therefore, it is a possibility that a combination of repeated sprints and ingestion of recommended amount of carbohydrates to maintain stable blood glucose, before exercising, may lead to hyperglycemia.

A recent study, published in January of 2019, tested the effect of carbohydrate intake in combination with short sprints before moderate-intensity exercise in young patients with type 1 diabetes. This study included eight patients with type 1 diabetes (3 males and 5 females) on basal insulin therapy, ages 14-35 and average HbA1c of 61 mmol/L. Study participants’ glucose levels were measured during and following four separate exercise routines after overnight fasting. All participants completed four 40-minute exercise sessions in random order on different days. Investigators measured participants’ heart rate, glucose, and lactate levels by blood sampling during and 2 hours after exercise.

Exercise sessions in the study were designed as follows:

• Moderate-Intensity cycling at 50% peak oxygen consumption.
• An intermittent high-intensity exercise, which included 40 minutes of moderate-intensity cycling at 50% peak oxygen consumption combined with 4-second sprints every 2 minutes and a final 10-second sprint.
• Moderate-intensity exercise after 3.5 mg per hour of exercise carbohydrates consumption (~10g per person).
• Intermittent high-intensity exercise following the same carbohydrate intake.

The data analysis of this study showed that there were significant differences in the time-averaged glucose AUC between four exercise routines. However, results presented that there was no significant difference in the mean time-averaged blood glucose AUC between moderate-intensity exercise with pre-exercise carbohydrate intake versus intermittent high-intensity exercise with pre-exercise carbohydrate intake, [0.2 mmol/l (3.6mg/dL) (95% CI -0.7, 1.1); P = 0.635]. Additionally, there was not a significant difference in the mean time-averaged area under the glucose curve between moderate-intensity and intermittent high-intensity exercise during exercise and recovery [-0.2 mmol/l (-3.6mg/dL) (95% CI -1.2, 0.8); P = 0.651]. Furthermore, it was noted that glucose levels were elevated for at least 30 minutes after both exercises with pre-exercise carbohydrate intakes.

Researchers of this study concluded that in spite of what was expected, there was no evidence to show that an intake of carbohydrates in combination with repeated sprints before moderate-intensity exercise leads to a significant elevation in glucose levels during and after exercise.

Practice Pearls:

• Intense exercise causes an elevation of glucose rather than a fall, seen with moderate-intensity, in insulin-dependent individuals with type 1 diabetes.
• Repeated sprinting prior to moderate-intensity resulted no significant elevation in blood glucose.
• The combination of pre-exercise carbohydrate and intermittent sprinting during moderate activity does not cause hyperglycemia in patients with type 1.

References:

Marliss EB, Vranic M (2002) Intense exercise has unique effects on both insulin release and its roles in glucoregulation: implications for diabetes. Diabetes 51: S271–S283

Bussau, V. A., et al. “A 10-s Sprint Performed Prior to Moderate-Intensity Exercise Prevents Early Post-Exercise Fall in Glycaemia in Individuals with Type 1 Diabetes.” SpringerLink, Springer, 22 June 2007, link.springer.com/article/10.1007/s00125-007-0727-8#Sec3.

Soon, W. H. K., et al. “Effect of Combining Pre‐Exercise Carbohydrate Intake and Repeated Short Sprints on the Blood Glucose Response to Moderate‐Intensity Exercise in Young Individuals with Type 1 Diabetes.” The Canadian Journal of Chemical Engineering, Wiley-Blackwell, 13 Feb. 2019, onlinelibrary.wiley.com/doi/abs/10.1111/dme.13914.

Ghazal Blair, Pharm.D. Candidate 2019, LECOM School of Pharmacy