The effect of physical activity on glycaemic control in women with gestational diabetes

Abstract

BACKGROUND: Exercise is important in the management of women with gestational diabetes mellitus (GDM), but there are few studies of its role in improving glucose levels. The emergence of commercial activity monitors has allowed larger volumes of data to be obtained over longer time periods than has previously been achieved by clinically validated actigraphy. This allows more extensive examination of the relationship between physical activity and glycaemic control. METHODS: Women enrolled in SMART MUMS WITH SMART PHONES 2 (SMs2), a randomised controlled trial of text messaging support for women after GDM, are provided with a wrist-worn activity monitor (Garmin Vivofit 4) that tracks steps in their third trimester. The women check and record their fasting and 2 h postprandial blood glucose levels (BGLs). Of the 180 women who are planned to be recruited for SMs2, we included those who had corresponding daily step and BGL records. Days with <1000 steps were excluded as it is likely that the activity monitor was not worn. We examined the association between steps with BGLs with a linear mixed effects model. RESULTS: Ten women were included in this study. The mean age was 34.0 +/-4.0 years and BMI 26.2+/-4.5 kg/m2. Amongst these women, there were 90 days with step and BGL data available. The mean steps on the previous day was 4814.51+/-2574.57 and on the same day was 4798.20+/-2311.03. The mean fasting BGL was 5.05+/-0.43mmol/l, post breakfast BGL 5.86+/- 0.57 mmol/l, post lunch BGL 6.13+/-0.58 mmol/l, post dinner BGL 6.42+/- 0.69 mmol/l and average postprandial BGL 6.10+/-0.47 mmol/l. There was a trend to increased steps on the previous day being associated with decreased fasting BGL, and for increased steps on the same day being associated with decreased post prandial BGL, with the highest effect after lunch. However, these trends did not meet statistical significance. CONCLUSIONS: This study suggests a possible trend to an association between physical activity and improved glycaemia in GDM, which if sustained across the cohort would warrant a full trial of commercial activity monitors for all women with GDM.