Patients with type 1 diabetes (T1D) can correct hyperglycemia following high-intensity interval training (HITT) using their usual insulin correction factor (ICF), researchers say.
"Most clinical attention in guiding our patients with T1D is currently focused on treating or avoiding the hypoglycemia that often results after moderate aerobic exercise," Dr. Ronnie Aronson of LMC Diabetes and Endocrinology in Ontario, Canada, told Reuters Health.
"Many people with T1D also enjoy HIIT, but it often leads to hyperglycemia, not hypoglycemia," he said by email. "Because it hasn't been studied as much, there are no guidelines in place to say how often it happens and whether or how to treat the hyperglycemia."
Exercise and diabetes. Source: iStock
To investigate, Dr. Aronson and colleagues conducted a randomized, crossover trial in 17 physically active individuals with T1D. Participants' mean age was 35; mean BMI, 25.5 kg/m2; and mean HbA1c, 7.2. Thirteen (76%) were male and all took multiple daily insulin injections.
After a two-month optimization period, with 300 units/mL insulin glargine used as the basal insulin, participants did four weekly 25-minute sessions of HIIT in a fasted state. If hyperglycemia (>8.0 mmol/L) occurred, they received a bolus insulin correction 15 minutes post-HIIT. The correction was based on their own ICF, adjusted by 0%, 50%, 100%, or 150%.
As reported online November 19 in Diabetes Care, 64 (90%) of 71 exercise trials resulted in hyperglycemia. At 40 minutes post-exercise, plasma glucose (PG) had increased from a mean of 8.8 mmol/L at baseline to 12.7 mmol/L.
After correction, the adjusted mean PG was significantly reduced for the 50% (-2.3 mmol/L), 100% (-4.7 mmol/L), and 150% (-5.3 mmol/L) study arms.
By contrast, PG had increased further in the 0% arm.
"We also found that even a full correction led to glucose control for the first 3-6 hours, but that patients continued to show relatively high glucose levels for the entire 24-hour period following HIIT exercise," Dr. Aronson noted.
Hypoglycemia was rare during the three hours following correction in all arms, and remained low over the following 21 hours, but was more frequent in the 100% and 150% correction arms.
"These findings should have a significant impact on our guidelines that support clinical care going forward," Dr. Aronson said. "Because of the traditional concern about hypoglycemia, people have been reluctant to take extra insulin after HIIT. Our findings will now provide the clear guidance that insulin is both safe and necessary if they find themselves experiencing high blood glucose after this type of exercise."
"Our findings are based on people exercising in a 'fasted' state - before breakfast," he added. "The effect of exercise and the impact of an extra insulin dose still need to be tested in HIIT performed later in the day, when food and food-related insulin injections may play an additional role."
Dr. Daniel S. Donovan, Jr., Director, Clinical Research at the Diabetes, Obesity and Metabolism Institute at Icahn School of Medicine at Mount Sinai in New York City, commented, "The management of patients with type 1 diabetes and exercise remains a vexing problem. It is even more problematic in that different types of exercise may result in different effects on glycemia."
"This study is very well designed and provides interesting information on the potential management of post-exercise hyperglycemia using a percentage of a patient's own ICF, under these rigorously controlled study conditions (with) a highly structured exercise regimen that was supervised," he told Reuters Health.
"It is unclear how this intervention would work in clinical practice with a more variable patient population," he said by email. "In the real world, patients may exercise in a fed or fasting state...at any time during the day."
Further, he noted, "These subjects only used multiple daily insulin injections. It is not clear if these findings would apply to other insulin regimens, including continuous subcutaneous insulin infusion via an insulin pump."
"Patients with other comorbid conditions, other concomitant medications that affect glycemia or a history of exercise-induced hypoglycemia might not be appropriate for this approach without further research," he added.
"More studies are needed under more real-world conditions before this approach could recommended for use in clinical practice," Dr. Donovan concluded.
Diabetes Care 2018.