Effects of a supervised exercise training in the management of women with gestational diabetes: preliminary results from a randomized controlled trial

Background. Gestational diabetes mellitus (GDM) is becoming increasingly common and it is associated with a number of metabolic and cardiovascular alterations. To date, only a few, small randomized controlled trials (RCTs) have investigated the effects of aerobic exercise training on maternal glyco-metabolic control and perinatal outcomes in women with GDM. Therefore, it remains still unclear whether these vascular and metabolic alterations may be reversed by regular exercise. In this study we aimed at investigating the effects of low-intensity aerobic exercise on the glycometabolic and cardiovascular outcomes in women with GDM. Subjects and Methods. 20 women with GDM were recruited in the GDM-FIT Study, a RCT (Clinicaltrials.gov ID: NCT03067662) to be randomly assigned between 18th-28th gestational week to structured aerobic exercise intervention (n=10) or standard care (n=10). Women in the control group received diet and physical exercise recommendations. Women in the intervention group received standard diet counseling and performed 40 minutes low intensity aerobic exercise three times per week at 30% heart rate reserve. Both groups underwent structured medical interview and psychological assessment in two separate occasions, at study entry and between 35th-37th gestational week, together with clinical and anthropometric measures. Weekly energy and carotid-to-femoral (CF) and radial (CR) pulse wave velocity (PWV) were also measured. Blood samples were stored for the determination of circulating pro-inflammatory metabolites and miRNA. In addition, a continuous glucose monitoring (CGM) system was applied to measure capillary blood glucose levels at 5-min timed intervals over 5 days at 32th-34th gestational week. Glucose variability measures and time spent in hypo- or hyperglycemia were also calculated. Results. Age, body-mass index (BMI) and HbA1c were similar between the two groups at study entry (standard care vs. exercise group, mean±SE): age (years) 34.5±1.4 vs. 34.3±0.9, BMI (kg/m2) 29.8±1.9 vs. 30±0.8, HbA1c (mmol/mol) 35±1.42 vs. 33.8±0.8, as well as in terms of CR-PWV (m/sec; 7.49±0.66 vs. 9.5±1.1) and CF-PWV (m/sec; 5.57±0.83 vs. 5.56±0.96). The metabolic parameters were similar between groups at 35th-37th gestational week. However, 4 women in the intervention group vs. 8 in the control group required insulin to reach the glycemic targets for pregnancy. Compared to the control group, women assigned to the exercise intervention showed a significant increase in weekly energy expenditure and a reduction in delta CR-PWV (1.4±0.74 vs. -2.2±1.4 m/sec). As compared to the corresponding non-exercise day, the CGM readings in the exercise group showed a significant decline of glucose levels during physical activity sessions, particularly after 30 minutes of exercise (P<0.05) up to 180 min after completion of exercise (P<0.005). With regard to the nocturnal and 24-h mean blood glucose levels, as well as time spent in hypo-/hyperglycemia and 24-h glucose variability, no significant differences were observed between the exercise vs. non-exercise days. Notably, as compared to the standard care arm, significantly lower 24-h mean blood glucose levels were observed during exercise days in the intervention group (P<0.05). Conclusions. These preliminary data indicate that a structured program of low-intensity aerobic exercise may have favorable effects on blood glucose and arterial stiffness in women with gestational diabetes.