The Effect of the Closed-Loop Control System on Blood Glucose Control With Exercise: A Critically Appraised Topic Melanie A. Mason, DAT, LAT, ATC, 1 Anne C. Russ, PhD, LAT, ATC, 2 Ryan T. Tierney, PhD, LAT, ATC, 2 and Jamie L. Mansell, PhD, LAT, ATC 2 1 Graceland University; 2 Temple University Context: Exercise can cause fluctuations in blood glucose control in type 1 diabetics. For athletes with type 1 diabetes, maintenance of blood glucose within an ideal range may be difficult. Objective: To determine, in individuals with type 1 diabetes, the effectiveness of the closed loop control system versus the open loop control system in keeping blood glucose levels in the ideal range with exercise. Data Sources: A search of PubMed was conducted in June of 2020 using the Boolean phrases: (closed loop control system OR artificial pancreas) AND type 1 diabetes AND exercise AND ideal range AND adolescents, artificial pancreas AND glucose prediction AND exercise. Study Selection: Titles were reviewed for relevance, the abstract was then assessed for applicability, and finally the full text was examined. Articles were included that examined the percent of time in the ideal blood glucose range when exercise occurred during that day. Articles were excluded that didn’t compare the closed loop and open loop control systems and articles that did not involve exercise. Data Extraction: The PEDro scale was used to determine the methodological quality of the included studies. The measure addressed was the percent of time in the ideal blood glucose range of 70-180 mg/dL. 95% Confidence Intervals and Cohen’s D were calculated for each article. Data Synthesis: The search yielded 268 articles and 3 were selected for inclusion. The two randomized controlled trials scored 9/10 on the PEDro scale and the randomized two-arm crossover clinical trial scored 9/10 on the PEDro scale. Percent time spent in the ideal blood glucose range when exercise was performed was significantly higher in the closed loop group versus the open loop group in each of the three studies. In one randomized control trial, mean time in the ideal range was 71.3% (SD = 17.6, 95% CI = 62.5, 80.10) in the closed loop group versus 64.7% (SD = 13.3, 95% CI = 58.1–71.4) in the open loop group. Cohen’s D was 0.4. In the second randomized control trial, mean time in the ideal range was 73.5% (SD = 8.4, 95% CI = 70.1, 76.9) for the closed loop group versus 50% (SD = 26.8, 95% CI = 39.1, 60.9). Cohen’s D was 1.2. The two-arm crossover clinical trial resulted in a mean time in target range of 84.1% (SD = 11.5, 95% CI = 79.0, 89.2) in the closed loop group versus 68.7% (SD = 13.9, 95% CI = 62.5, 74.9) in the open loop group. Cohen’s D was 1.2. Conclusions: For adolescents with type 1 diabetes who exercise, the closed loop control system maintains blood glucose levels in the ideal range for a longer percent of time versus an open loop system. Each patient should be evaluated on a case-by-case basis with his/her healthcare team. Future research should examine the closed loop control system on specific energy systems. Keywords: adolescents, artificial pancreas, diabetes Clinical Scenario According to the 2020 National Diabetes Statistics Report, approx- imately 187,000 children and adolescents in the United States have Type 1 diabetes. 1 In Type 1 diabetes, an individual’s autoimmune system destroys the insulin-secreting pancreatic β cells, which reside in the Islets of Langerhans. 2,3 Once the β cells are destroyed, the pancreas no longer produces insulin, which is a vital hormone responsible for maintenance of blood glucose levels. 3 Insulin is needed for intracellular transport of glucose into various tissues (e.g., muscle, adipose), which allows for the creation and storage of glycogen for use as an energy source for muscle contraction. 3 In order for efficient synthesis and storage of glycogen in muscle tissue, blood glucose levels need to be controlled through readily available insulin. 3 The ideal range of blood glucose levels is generally considered to be between 70 and 180 mg/dl. 4,5 In order to avoid hypo- and hyperglycemia, and stay in the ideal blood glucose range, indivi- duals with Type 1 diabetes must balance physical activity, exercise, carbohydrate intake, and insulin administration. 6 The response of blood glucose to physical activity and exercise are highly variable with intensity and duration. 6 Moderate and vigorous exercise sessions increase the risk of hypoglycemia in individuals with Type 1 diabetes. 7 Because of this, additional carbohydrate intake and/or reductions in insulin administration are required to maintain glucose levels in the ideal range. 6 During exercise, an individual with Type 1 diabetes is responsible for making adjustments that will impact blood glucose levels. The individual must determine how intense and how long of an activity session they will undergo and adjust their insulin administration and/or carbohydrate intake accordingly. 6 Because individuals with Type 1 diabetes self- administer insulin through injections, pens, and insulin pumps, there is a potential for error that impacts blood glucose levels, glycogen synthesis, and storage. 6 Eliminating individual modifica- tions to insulin administration takes human error out of the blood glucose equation. 6 The closed-loop control system, which eliminates the indi- vidual making insulin adjustments, was first approved by the U.S. Food and Drug Administration in 2016. 8 Closed-loop control Mason is with Graceland University, Lamoni, IA, USA. Russ, Tierney, and Mansell are with Temple University, Philadelphia, PA, USA. Mason (mason6@graceland. edu) is corresponding author. 241 International Journal of Athletic Therapy and Training, 2021, 26, 241-244 https://doi.org/10.1123/ijatt.2020-0109 © 2021 Human Kinetics, Inc. CRITICALLY APPRAISED TOPIC Unauthenticated | Downloaded 09/03/21 01:00 PM UTC