Increased placental mitochondrial fusion in gestational diabetes mellitus: an adaptive mechanism to optimize feto-placental metabolic homeostasis?

INTRODUCTION: Gestational diabetes mellitus (GDM), a common pregnancy disorder, increases the risk of fetal overgrowth and later metabolic morbidity in the offspring. The placenta likely mediates these sequelae, but the exact mechanisms remain elusive. Mitochondrial dynamics refers to the joining and division of these organelles, in attempts to maintain cellular homeostasis in stress conditions or alterations in oxygen and fuel availability. These remodeling processes are critical to optimize mitochondrial function, and their disturbances characterize diabetes and obesity. METHODS AND RESULTS: Herein we show that placental mitochondrial dynamics are tilted toward fusion in GDM, as evidenced by transmission electron microscopy and changes in the expression of key mechanochemical enzymes such as OPA1 and active phosphorylated DRP1. In vitro experiments using choriocarcinoma JEG-3 cells demonstrated that increased exposure to insulin, which typifies GDM, promotes mitochondrial fusion. As placental ceramide induces mitochondrial fission in pre-eclampsia, we also examined ceramide content in GDM and control placentae and observed a reduction in placental ceramide enrichment in GDM, likely due to an insulin-dependent increase in ceramide-degrading ASAH1 expression. CONCLUSIONS: Placental mitochondrial fusion is enhanced in GDM, possibly as a compensatory response to maternal and fetal metabolic derangements. Alterations in placental insulin exposure and sphingolipid metabolism are among potential contributing factors. Overall, our results suggest that GDM has profound impacts on placental mitochondrial dynamics and metabolism, with plausible implications for the short-term and long-term health of the offspring.

Heterogeneity of maternal characteristics and impact on gestational diabetes (GDM) risk-Implications for universal GDM screening?

OBJECTIVE: To study the incidence of gestational diabetes mellitus (GDM) in relation to phenotypic characteristics and gestational weight gain (GWG) among women at high risk for GDM. MATERIALS AND METHODS: This is a secondary analysis of a GDM prevention study (RADIEL), a randomized controlled trial conducted in Finland. 269 women with a history of GDM and/or a pre-pregnancy body mass index (BMI) ≥ 30 kg/m(2) were enrolled before 20 weeks of gestation and divided into four groups according to parity, BMI and previous history of GDM. The main outcome was incidence of GDM. RESULTS: There was a significant difference in incidence of GDM between the groups (p < 0.001). Women with a history of GDM and BMI <30 kg/m(2) showed the highest incidence (35.9%). At baseline they had fewer metabolic risk factors and by the second trimester they gained more weight. There was no interaction between GWG and GDM outcome and no significant difference in the prevalence of diabetes-associated antibodies. CONCLUSION: Despite a healthier metabolic profile at baseline the non-obese women with a history of GDM displayed a markedly higher cumulative incidence of GDM. GWG and the presence of diabetes-associated antibodies were not associated with GDM occurrence among these high-risk women. Key message Despite a healthier metabolic profile at baseline the non-obese women with previous gestational diabetes mellitus display a markedly higher cumulative incidence of gestational diabetes mellitus.