Rationale and Protocol for the Time to Move Randomized Crossover Trial: Morning versus Evening Time Physical Activity and CGM-Assessed Glucose Levels in Individuals with Pregnancy Hyperglycemia

Samantha Frances Ehrlich^1*Bethany Rand Hallenbeck²Jordan Lewis¹Fatemeh Yousefi¹John I Miller¹Nikki B Zite³Kimberly B Fortner³Walter W Schoutko³Scott E Crouter¹Hollie Raynor¹Jill M Maples³

• ¹The University of Tennessee, Knoxville, Knoxville, United States
• ²Kaiser Permanente Division of Research, Pleasanton, United States
• ³The University of Tennessee Graduate School of Medicine, Knoxville, United States

Background: For most patients with pregnancy hyperglycemia, treatment includes lifestyle behavioral counseling for healthy diet and physical activity (PA). Outside of pregnancy, emerging evidence suggests that the timing of PA (e.g., in the morning vs. in the evening) may modify its glucose lowering effects. PA is an evidence-based, non-pharmacological strategy for managing glucose levels; recommendations for PA timing could improve glucose levels in individuals with pregnancy hyperglycemia. Objective: To describe the rationale for and protocol of the Time to Move Randomized Crossover Trial evaluating the effects of morning vs. evening PA on glucose levels across the 24-hour cycle. Methods: Eligibility criteria include singleton pregnancies in patients 18-40 years of age, identified as Gestational Glucose Intolerant [(GGI), a non-fasted, 50-g glucose challenge test, 1-hr value ≥ 130 mg/dl] or Gestational Diabetes Mellitus [(GDM), by the one-or two-step procedure, at ≥ 24 weeks]. Consented participants are randomized to first perform either morning time (between 5am-9am, within 30-40 minutes of starting breakfast) or evening time (between 4pm-8pm, within 30-40 minutes of starting dinner) PA; all episodes of PA consist of 30 minutes of moderate intensity walking or stepping. Participants ultimately contribute 2-days in each of the three treatment conditions: morning PA, evening PA, and no PA, with one washout day between treatment conditions. Timestamped glucose measures are obtained from Dexcom G6 or G7 continuous glucose monitors (CGM). The primary analysis will be intention to treat; per protocol associations will also be explored. PA adherence is assessed by ActiGraph PA monitoring devices (i.e., the CentrePoint Insight Watch, worn on the non-dominant wrist), which provides continuous timestamped estimates of movement. Participants upload photos (i.e., in real time) of all foods and beverages consumed throughout the study period; the timestamps of these photos are used to identify postprandial periods. One 24-hour dietary recall, aided by the photo uploads, is also completed for each treatment condition. Conclusions: The Time to Move Randomized Crossover Trial addresses the gap in scientific knowledge on whether the timing of PA may potentially be leveraged to maximize glucose control in individuals with pregnancy hyperglycemia.