Aim: Exercise is a useful adjunct to the standard treatment of all people with diabetes. The primary intention of this study was to investigate the effect of prescribing 10-minutes of post meal walking (PMW) three times daily on glucose levels (postprandial, 24h and nocturnal), physical activity and birth outcomes in women with gestational diabetes mellitus (GDM).
Methods: A randomised clinical trial. Women with GDM (diet controlled) <30wk gestation (n=40, 33±4 y, 28.2±5.5 kg.m-2) were randomised to i) standard-care alone (CTL; includes recommendation ~30-minutes physical activity most days.week-1), or ii) PMW (standard-care with advice to perform daily 10-minute walks within 1-hour of main meals) for ~seven weeks. Interstitial glucose was measured for 7-days at ~28- and ~35-weeks’ gestation using continuous glucose monitoring (CGM). Physical activity and adherence was measured for 7-days at 28-, 32-, and 35-weeks’ gestation using an inclinometer (ActivPal). Birth outcomes (e.g., type of birth, weeks’ gestation, birth weight) were collected. Demographics and birth outcomes were compared using unpaired t-test and chi-square analyses and Fixed effects Linear Mixed Model and Tukey post hoc analysed main outcomes.
Results: Adherence to prescribed physical activity was higher for PMW vs CTL at 28 and 32 (by 20.9 ± 15.7 minutes.day-1) but not at 35 wks (interaction: p=0.01). Mean 3h postprandial glucose (dinner) was significantly higher for PMW vs CTL (by 0.29 ± 0.58 mmol.L-1; group: p=0.04), with no difference for postprandial glucose (breakfast and lunch). iAUC was 9% higher for PMW compared to CTL (group: p=0.05). Sitting time and incidental activity (stepping time) were higher and lower, respectively for PMW compared to CTL (group: both p<0.05). Across the cohort, 14% of deliveries presented macrosomia (birth weight>4000g), and 4.5% any incidences of hypoglycaemia in the neonate (birth outcomes no significance).
Discussion: Findings from this clinical trial show that whilst PMW had greater adherence to recommended physical activity, the glucose responses, sedentary (sitting) time and incidental activity were worse compared to CTL. In contrast to our hypothesis, accumulating walking in 10-min bouts was not an effective alternate to continuous physical activity recommendations. PMW may not have been of sufficient duration or intensity to mitigate postprandial hyperglycaemia in women with GDM. Future research could explore the impact of different types of physical activity behaviour, to assist in helping to control maternal glucose levels.