Aims/hypothesis: This study aimed to determine, in women with gestational diabetes (GDM), the changes in insulin sensitivity (Matsuda Insulin Sensitivity Index; ISOGTT), insulin response and disposition index (DI) from late pregnancy (34-37 weeks gestation, T1), to early postpartum (1-5 days, T2) and late postpartum (6-12 weeks, T3). A secondary aim was to correlate the longitudinal changes in maternal lipids, adipokines, cytokines and weight in relation to the changes in ISOGTT, insulin response and DI.
Methods: ISOGTT, insulin response and DI were calculated at the three time points (T1, T2 and T3) using the results of a 75 g OGTT. Adipokines, cytokines and lipids were measured prior to each OGTT. Linear mixed-effects models were used to compare changes across each time point. Changes in ISOGTT, insulin response and DI were correlated with changes in maternal adipokines, cytokines and lipids at each time point.
Results: A total of 27 women completed all assessments. Compared with T1, ISOGTT was 11.20 (95% CI 8.09, 14.31) units higher at 1-5 days postpartum (p < 0.001) and was 5.49 (95% CI 2.38, 8.60) units higher at 6-12 weeks postpartum (p < 0.001). Compared with T1, insulin response values were 699.6 (95% CI 957.5, 441.6) units lower at T2 (p < 0.001) and were 356.3 (95% CI 614.3, 98.3) units lower at T3 (p = 0.004). Compared with T1, the DI was 6434.1 (95% CI 2486.2, 10,381.0) units higher at T2 (p = 0.001) and was 4262.0 (95% CI 314.6, 8209.3) units higher at T3 (p = 0.03). There was a decrease in mean cholesterol, triacylglycerol, LDL-cholesterol and VLDL-cholesterol from T1 to T2 (all p < 0.001), and an increase in mean C-reactive protein, IL-6 and IL-8 from T1 to T2 (all p < 0.001). Mean leptin decreased from T1 to T2 (p = 0.001). There was no significant change in mean adiponectin (p = 0.99) or TNF-α (p = 0.81) from T1 to T2. The mean maternal BMI decreased from T1 to T2 (p = 0.001) and T3 (p < 0.001). There were no significant correlations between any measure of change in ISOGTT, insulin response and DI and change in maternal cytokines, adipokines, lipids or weight from T1 to T2.
Conclusions/interpretation: In women with GDM, delivery was associated with improvement in both insulin sensitivity and insulin production within the first few days. Improvement in insulin production persisted for 6-12 weeks, but insulin sensitivity deteriorated slightly. These changes in glucose metabolism were not associated to changes in lipids, leptin, inflammation markers or body weight.
Trial registration: ClinicalTrials.gov NCT02082301.
Keywords: Disposition index; Gestational diabetes; Insulin response; Insulin sensitivity.