Evaluation of Light Exercise in the Treatment of Gestational Diabetes

The metabolic goal of therapy in gestational diabetes (GD) is to maintain euglycemia, and when it is not achieved with diet alone, insulin therapy is added (1). Physical training has both acute and long-term effects on insulin sensitivity, insulin secretion, and glucose metabolism in both nondiabetic and diabetic subjects (2), and the benefit of training has also been shown in patients with GD, where controlled training achieves euglycemia with no need for insulin treatment (3). Nevertheless, physical exercise of moderate intensity has been associated with uterine contractions unless performed with the arms (4).

The clinical observation that light postprandial exercise in patients with GD was useful in decreasing blood glucose (BG) prompted this controlled crossover study, which had the aim of assessing the magnitude of its effect in women with GD.

A total of 20 non–exercise-trained women with GD (Third Workshop-Conference on Gestational Diabetes Mellitus criteria) were studied after diagnosis on two different days (3–7 days apart, first day regime randomly allocated). The study began between 8:00 a.m. and 9:00 a.m., and capillary blood glucose (CBG) was measured (Hemocue, Angelholm, Sweden) during fasting and 1 and 2 h after a standard breakfast consisting of 20 g of carbohydrates. On the control day, the women remained seated throughout the observation period, and in the study day, they walked self-paced on a flat surface in the first hour after breakfast and remained seated during the second hour. The mean age (means ± SD) was 33.5 ± 4.6 years, the gestational age was 30.7 ± 5.5 weeks, and the weight was 69.6 ± 9.4 kg. For data analysis, the t test for paired data was used (variables normally distributed).

We found significant differences (control day versus study day) in 1-h postprandial BG (6.02 ± 0.78 vs. 5.35 ± 0.69 mmol/l, P = 0.001), 1-h postprandial heart rate (82 ± 9 vs. 91 ± 10 bpm, P = 0.002), and 1-h BG excursion (1.79 ± 0.6 vs. 1.07 ± 0.68 mmol/l, P < 0.001), whereas no differences were observed in fasting and 2-h postprandial BG, basal and 2-h postprandial heart rate, or basal and 1- and 2-h postprandial blood pressure. There was a trend toward a higher effect of exercise in 1-h postprandial BG in those women with higher levels on the control day (r = 0.43, P = 0.058). No untoward effect was observed.

We have shown that light postprandial exercise decreases postprandial BG excursion in women with GD, and this has been achieved with very light exercise (2.52 km in 1 h, 9 bpm increase in heart rate). We conclude that in addition to the benefits of physical training on blood glucose control, women with GD could benefit from light postprandial exercise and potentially avoid or delay insulin therapy. In clinical practice, light postprandial exercise could translate into avoiding rest at that time.