January 27, 2017
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Carbohydrate, insulin dose adjustments may prevent exercise-associated hypoglycemia in type 1 diabetes

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Adults with type 1 diabetes who exercise regularly should consider changes in nutrition management and bolus insulin dose adjustments to avoid the risk for hypoglycemia while also monitoring blood glucose levels before, during and after any aerobic activity, according to a consensus statement released by an international team of researchers.

“Exercise has numerous health benefits for type 1 diabetes, including enhanced insulin sensitivity and reduced diabetes-related complications,” Michael C. Riddell, PhD, professor and graduate program director at the School of Kinesiology and Health Science at York University in Toronto, told Endocrine Today. “It can cause acute changes to glucose control, however. Good exercise management for type 1 diabetes requires a sound understanding of the physiology behind glucose turnover during a variety of exercise modes and intensities.”

Michael Riddel
Michael C. Riddell

In developing the consensus statement, published online in Lancet Diabetes & Endocrinology, Riddell and colleagues reviewed observational studies and clinical trials on exercise management for people with type 1 diabetes who exercise regularly. For most adults, the reasonable starting blood glucose range for aerobic exercise lasting up to 1 hour is 7 mmol/L to 10 mmol/L; higher concentrations may be acceptable in situations where added protection against hypoglycemia is needed.

For prolonged aerobic exercise, increased carbohydrate consumption at a rate of 0.5 g/kg of body weight per hour is recommended for patients on multiple daily insulin injections, Riddell said, along with a reduction in insulin delivered at the meal before exercise. For patients using insulin-pump therapy, basal rate reductions performed 60 to 90 minutes before the start of exercise can reduce hypoglycemia risk, he added.

To prevent nocturnal hypoglycemia after prolonged exercise, basal insulin also should be reduced by about 20% at bedtime for 6 hours for pump users and by 20% in those on multiple daily insulin injections, Riddell said.

Resistance-based activities (eg, weight training), some forms of competitive sports and high-intensity interval training can cause acute hyperglycemia in type 1 diabetes, the researchers noted.

“This must be managed conservatively, since insulin sensitivity remains elevated for up to 24 hours after exercise, and insulin excessive administration may increase nocturnal hypoglycemia risk some hours later,” Riddell said.

Those with elevated ketones, recent episodes of hypoglycemia and diabetes-related complications may have contraindications for exercise and should discuss any regimen with their health care provider, the researchers noted. Those preparing for exercise should be aware of their starting glucose level, have blood glucose monitoring equipment and snacks to treat hypoglycemia, as well as some form of diabetes identification, they wrote.

“These guidelines fulfill a major unmet need to help patients with type 1 diabetes, and their health care professionals, to overcome the various barriers for exercise, and this, in turn, should help them to achieve the multitude of health benefits that exercise affords” Rémi Rabasa-Lhoret, MD, director of the metabolic diseases research unit at the Montreal Clinical Research Institute, said in a statement.

Riddell said more studies are needed to determine how to manage post-exercise hyperglycemia safely and effectively in patients with type 1 diabetes.

“Studies that help demonstrate efficacy of automated insulin delivery systems during and after exercise are also urgently needed,” he said. by Regina Schaffer

For more information:

Michael C. Riddell, PhD, can be reached at the School of Kinesiology and Health Science, Muscle Health Research Centre, York University, Toronto, Ontario, Canada M3J 1P3; email: mriddell@yorku.ca.

Disclosure: JDRF funded this research. Riddell reports receiving personal fees from Ascensia, Diabetes Care, Insulet Corp., Lilly and Medtronic. Please see the full study for the other authors’ relevant financial disclosures.