Association between maternal and umbilical cord serum dipeptidyl peptidase IV in pregnant women with and without gestational diabetes mellitus

Association of DPP-4 Concentrations with the Occurrence of Gestational Diabetes Mellitus and Excessive Gestational Weight Gain

Gestational diabetes mellitus (GDM) is considered one of the most common diseases that occur during pregnancy. In addition to increasing the risk of numerous complications throughout gestation, it is also believed to have a long-term potential to impact the risk of developing type 2 diabetes mellitus (T2DM) and cardiovascular disease for the mother and her offspring. While there are clear guidelines for healthy weight gain in pregnancy depending on pre-pregnancy BMI, as well as dietary and training recommendations to achieve this, an increasing number of women are experiencing excessive gestational weight gain (EGWG). Such patients have a higher risk of developing GDM and gestational hypertension, as well as requiring caesarian delivery. Dipeptidyl peptidase-4 (DPP-4) is a glycoprotein that seems to play an important role in glucose metabolism, and inhibition of its activity positively affects glucose regulation. The aim of our study was to compare DPP-4 concentrations in patients with GDM and EGWG with healthy women. DPP-4 levels were assessed in serum and urine samples collected on the day of delivery. The bioelectrical impedance analysis (BIA) method was also used to analyze the body composition of patients on the second day of the postpartum period. DPP-4 serum concentrations were significantly higher in patients in the GDM and EGWG groups compared to healthy women. Urinary DPP-4 concentrations were significantly higher in the control and GDM groups than in the EGWG group. Serum DPP-4 levels were positively correlated with BMI measured before pregnancy, on the delivery day, and in the early postpartum period, among other factors. According to our knowledge, this is the first study to determine DPP-4 levels in EGWG patients. DPP-4 may be related to the occurrence of GDM and EGWG; however, this requires further research.

Incretins as a Potential Treatment Option for Gestational Diabetes Mellitus

Gestational diabetes mellitus (GDM) is a metabolic disease affecting an increasing number of pregnant women around the world. It is not only associated with numerous perinatal complications but also has long-term consequences impacting maternal health and fetal development. To prevent them, it is important to keep glucose levels under control. As much as 15-30% of GDM patients will require treatment with insulin, metformin, or glyburide. With that in mind, it is crucial to keep searching for novel and improved pharmacotherapies. Nowadays, there are ongoing studies investigating the use of other groups of drugs that have proven successful in the treatment of T2DM. Glucagon-like peptide-1 (GLP-1) receptor agonist and dipeptidyl peptidase-4 (DPP-4) inhibitor are among the drugs targeting the incretin system and are currently receiving significant attention. The aim of our review is to demonstrate the potential of these medications in treating GDM and preventing its later complications. It seems that both groups may be successful in the GDM management used alone or as an addition to better-known drugs, including metformin and glyburide. However, more clinical trials are needed to confirm their importance in GDM treatment and to demonstrate effective therapeutic strategies.

Incretin Hypersecretion in Gestational Diabetes Mellitus

CONTEXT

Incretins are crucial stimulators of insulin secretion following food intake. Data on incretin secretion and action during pregnancy are sparse.

OBJECTIVE

The aim of the study was to investigate the incretin response during an oral glucose tolerance test (OGTT) in pregnant women with and without gestational diabetes mellitus (GDM).

DESIGN

We analyzed data from the ongoing observational PREG study (NCT04270578).

SETTING

The study was conducted at the University Hospital Tübingen.

PARTICIPANTS

We examined 167 women (33 with GDM) during gestational week 27 ± 2.2.

INTERVENTION

Subjects underwent 5-point OGTT with a 75-g glucose load.

MAIN OUTCOME MEASURES

We assessed insulin secretion and levels of total glucagon-like peptide-1 (GLP-1), glucose-dependent insulinotropic peptide (GIP), glicentin, and glucagon during OGTT. Linear regression was used to analyze the relation of GLP-1 and glucose with insulin secretion and the association of incretin levels on birth outcome.

RESULTS

Insulin secretion was significantly lower in women with GDM (P < 0.001). Postload GLP-1 and GIP were ~20% higher in women with GDM (all P < 0.05) independent of age, body mass index, and gestational age. GLP-1 increase was associated with insulin secretion only in GDM, but not in normal glucose tolerance. Postprandial GLP-1 levels were negatively associated with birth weight.

CONCLUSIONS

The more pronounced GLP-1 increase in women with GDM could be part of a compensatory mechanism counteracting GLP-1 resistance. Higher GLP-1 levels might be protective against fetal overgrowth.

Downregulation of large-conductance Ca2+-activated K+ channels in human umbilical arterial smooth muscle cells in gestational diabetes mellitus

AIMS

We investigated the changes in large-conductance Ca²⁺-activated K⁺ (BK_Ca) channels from human umbilical arterial smooth muscle cells experiencing gestational diabetes mellitus (GDM).

MAIN METHODS

Whole-cell patch-clamp technique, arterial tone measurement, RT-PCR, Quantitative real-time PCR, western blot were performed in human umbilical arterial smooth muscle cells.

KEY FINDINGS

Whole-cell BK_Ca current density was decreased in the GDM group compared with the normal group. The vasorelaxant effects of the synthetic BK_Ca channel activator NS-1619 (10 μM) were impaired in the GDM group compared with the normal group. Reverse-transcription polymerase chain reaction (RT-PCR), real-time RT-PCR, and western blot analyses suggested that the mRNA, total RNA, and protein expression levels of the BK_Ca channel were decreased in the GDM group relative to the normal group. In addition, the expression levels of protein kinase A and protein kinase G, which regulate BK_Ca channel activity, remained unchanged between the groups. Applying the BK_Ca channel inhibitor paxilline (10 μM) induced vasoconstriction and membrane depolarization of isolated umbilical arteries in the normal group but showed less of an effect on umbilical arteries in the GDM group.

SIGNIFICANCE

Our results demonstrate for the first time impaired BK_Ca current and BK_Ca channel-induced vasorelaxation activities that were not caused by impaired BK_Ca channel-regulated protein kinases, but by decreased expression of the BK_Ca channels, in the umbilical arteries of GDM patients.

Late gestational testosterone exposure causes glucose deregulation and elevated cardiac VCAM-1 and DPP-4 activity in rats

CONTEXT

Increased vascular cell adhesion molecule-1 (VCAM-1) has been reported to be a critical link between obesity and atherosclerotic cardiovascular diseases while dipeptidyl peptidase-4 (DPP-4) has been implicated in the development of disrupted glucose regulation and inflammation.

OBJECTIVE

This study aimed to investigate the effect of gestational testosterone exposure on glucose metabolism, atherogenic dyslipidemia, as well as circulating and cardiac VCAM-1, oxidative stress biomarkers and DPP-4 activity in pregnant rats.

METHODS

Pregnant Wistar rats received either vehicle or testosterone (0.5 mg/kg; sc) between gestational days 14 and 19.

RESULTS

Gestational testosterone exposure caused impaired glucose homeostasis that was accompanied with atherogenic dyslipidemia, elevated circulating and cardiac levels of VCAM-1, uric acid, malondialdehyde as well as increased DPP-4 activity. However, nitric oxide levels were decreased.

CONCLUSION

This study shows that gestational testosterone exposure causes glucose deregulation and atherogenic dyslipidemia that is accompanied by increased circulating and cardiac VCAM-1 and DPP-4 activity.

Placental extracellular vesicles express active dipeptidyl peptidase IV; levels are increased in gestational diabetes mellitus

Gestational diabetes mellitus (GDM) is the most common metabolic disorder in pregnancy and is characterized by insulin resistance and decreased circulating glucagon-like peptide-1 (GLP-1). GDM resolves rapidly after delivery implicating the placenta in the disease. This study examines the biological functions that cause this pathology. The placenta releases syncytiotrophoblast-derived extracellular vesicles (STB-EVs) into the maternal circulation, which is enhanced in GDM. Dipeptidyl peptidase IV (DPPIV) is known to play a role in type 2 diabetes by breaking down GLP-1, which in turn regulates glucose-dependent insulin secretion. STB-EVs from control and GDM women were analysed. We show that normal human placenta releases DPPIV-positive STB-EVs and that they are higher in uterine than paired peripheral blood, confirming placental origin. DPPIV-bound STB-EVs from normal perfused placentae are dose dependently inhibited with vildagliptin. DPPIV-bound STB-EVs from perfused placentae are able to breakdown GLP-1 in vitro. STB-EVs from GDM perfused placentae show greater DPPIV activity. Importantly, DPPIV-bound STB-EVs increase eightfold in the circulation of women with GDM. This is the first report of STB-EVs carrying a biologically active molecule that has the potential to regulate maternal insulin secretion.