(869) Vigorous exercise is associated with reduced insulin resistance in pregnancies at risk for gestational diabetes

Objective:
To determine if intensity of physical activity is associated with insulin resistance in pregnant people at risk for gestational diabetes (GDM).

Study Design:
In a cohort of pregnant people at high risk of GDM (n=102), we used the International Physical Activity Questionnaire-Short Form (IPAQ-SF) to estimate hours/week spent sitting, walking, in moderate exercise, or in vigorous exercise at 10-15 and 24-32 weeks' gestation. We used a 75g oral glucose tolerance test (GTT) to calculate the Matsuda index, a measure of insulin sensitivity (opposite of insulin resistance) at 24-32 weeks’ gestation. Our primary hypothesis was that more time spent sitting at 10-15 weeks’ would be associated with greater insulin resistance (lower Matsuda index, log transformed) at 24-32 weeks’ in linear regression models adjusted for age and BMI. Secondary analyses evaluated the relationship between time spent sitting, walking, in moderate physical activity, or in vigorous physical activity at both timepoints and insulin resistance at 24-32 weeks’ gestation. We replicated findings from secondary analyses in a distinct cohort (n=104) using the Pregnancy Physical Activity Questionnaire (PPAQ) for physical activity and Matsuda index calculated using a 100g GTT at 24-32 weeks' gestation.

Results:
There was no association between hours spent sitting per day at 10-15 weeks’ gestation and insulin resistance at 24-32 weeks’ (β=0.01, 95% CI [-0.03, 0.05], p=0.67, Figure 1). There was no association of walking or moderate physical activity at either timepoint with insulin resistance at 24-32 weeks’. Vigorous activity at 24-32 weeks’ gestation was associated with lower insulin resistance (β=0.12, 95% CI [0.04,0.20]) at the same timepoint. This was replicated in an independent cohort, with increased hours of vigorous physical activity per week at 24-32 weeks' gestation associated with lower insulin resistance cross-sectionally at 24-32 weeks' in an adjusted model (β=0.13, 95% CI [0.02,0.24]).

Conclusion:
Vigorous activity at 24-32 weeks’ gestation appears protective against insulin resistance in pregnant people with GDM risk factors.