Reduced GLP-1 Secretion at 30 Minutes After a 75-g Oral Glucose Load Is Observed in Gestational Diabetes Mellitus: A Prospective Cohort Study

Association of GLP-1 secretion with parameters of glycemic control in women after gestational diabetes mellitus

INTRODUCTION

Women with a history of gestational diabetes mellitus (GDM) are at high risk of developing type 2 diabetes, while the exact mechanisms underlying its pathophysiology are still unclear. We investigated the association of glucagon-like peptide-1 (GLP-1) response to oral glucose with parameters of glycemic control in women with previous GDM in the prospective PPSDiab (Prediction, Prevention, and Subclassification of Type 2 Diabetes) study.

RESEARCH DESIGN AND METHODS

Glucose metabolism parameters and GLP-1 secretion were analyzed during oral glucose tolerance test (OGTT) in women with previous GDM (n=129) and women with a history of normal glucose tolerance (n=67) during pregnancy (controls). First- and second-phase insulin and GLP-1 secretion in relation to plasma glucose (PG) levels were assessed, and development of pre-diabetes was analyzed after 5-year follow-up among women with previous GDM and a normal glycemic state at baseline (n=58).

RESULTS

The area under the curve (AUC during the OGTT 0-120 min) of PG and insulin but not GLP-1 differed significantly between post-GDM women and controls. However, women with previous GDM had a significantly decreased GLP-1 response in relation to PG and plasma insulin during the second phase of the OGTT. After a follow-up of 5 years, 19.0% post-GDM women with a normal glycemic state at the baseline visit developed abnormal glucose metabolism. The total, first- and second-phase AUC GLP-1/PG and GLP-1/insulin ratios were not associated with development of abnormal glucose tolerance.

CONCLUSIONS

Women with previous GDM showed a reduced GLP-1 response in relation to PG and insulin concentrations indicating early abnormalities in glucose metabolism. However, the altered GLP-1 response to oral glucose did not predict progression to pre-diabetes and type 2 diabetes in the first 5 years after GDM.

Pregnancy glucagon-like peptide 1 predicts insulin but not glucose concentrations

AIMS

Incretin hormones glucagon-like peptide 1 (GLP-1) and gastric inhibitory peptide (GIP) cause increased insulin secretion in non-pregnant adults, but their role in pregnancy, where there are additional metabolically-active hormones from the placenta, is less clear. The aim of the present study was to assess if fasting and post-load incretin concentrations were predictive of pregnancy insulin and glucose concentrations.

METHODS

Pregnant women (n = 394) with one or more risk factors for gestational diabetes were recruited at 28 weeks for a 75 g oral glucose tolerance test (OGTT). Glucose, insulin, GLP-1 and GIP were measured in the fasting state and 120 min after glucose ingestion.

RESULTS

Fasting plasma GLP-1 concentrations were associated with plasma insulin (standardised β' 0.393 (0.289-0.498), p = 1.3 × 10-12; n = 306), but not with glucose concentrations (p = 0.3). The association with insulin was still evident when adjusting for BMI (β' 0.271 (0.180-0.362), p = 1.1 × 10-8; n = 297). Likewise, at 120 min the OGTT GLP-1 concentrations were associated with plasma insulin concentrations (β' 0.216 (0.100-0.331), p  = 2.7 × 10-4; n = 306) even after adjusting for BMI (β' 0.178 (0.061-0.294), p = 2.9 × 10-3; n = 296), but not with glucose (p  = 0.9). GIP concentrations were not associated with insulin or glucose concentrations at either time point (all p  > 0.2). In pregnancy plasma GLP-1, but not GIP, concentrations appear to be predictive of circulating insulin concentrations, independently of associations with BMIs.

CONCLUSIONS

These results suggest that the relationship between insulin and incretins is preserved in pregnancy, but that other factors, such as placental hormones or counter-regulatory hormones, may be more important determinants of glycaemia and gestational diabetes aetiology.

Non-altered incretin secretion in women with impaired fasting plasma glucose in the early stage of pregnancy: a case control study

BACKGROUNDS

Glucagon-like peptide 1 (GLP-1) and glucose-dependent insulinotropic peptide (GIP) may be involved in pathogenesis of gestational diabetes mellitus (GDM). The aim was to compare GLP-1 and GIP production in fasting state and during 3 h mixed meal tolerance test (MMTT) measured by mean area under the curve (AUC) between pregnant women with normal and impaired fasting glucose in an early phase of pregnancy, and healthy non-pregnant controls.

METHODS

This study was undertaken as a case-control study. Repeated measurement of fasting plasma glucose ≥ 5.1 mmol/L and < 7.0 mmol/L during the first trimester of pregnancy and exclusion of overt diabetes according to IADSPG criteria was used to find women with impaired fasting glucose (n = 22). Age-matched controls consisted of healthy pregnant (n = 25) and non-pregnant (n = 24) women. In addition to incretins, anthropometric parameters and markers of insulin resistance and beta-cell function were assessed. Variables were summarized as median (interquartile range).

RESULTS

Fasting GLP-1 and GIP concentration or their AUC during MMTT did not significantly differ between pregnant women with impaired fasting plasma glucose [GLP-1_AUC 19.0 (53.1) and GIP_AUC 302 (100) pg/mL/min] and healthy pregnant women [GLP-1_AUC 16.7 (22.3) and GIP_AUC 297 (142) pg/mL/min] or non-pregnant controls [GLP-1_AUC 16.8 (9.8) and for GIP_AUC 313 (98) pg/mL/min]. Although women with impaired fasting glucose were more obese and showed decreased beta-cell function, there were not significant correlations between incretin production and parameters of insulin secretion, insulin resistance, or obesity.

CONCLUSIONS

Women with impaired fasting plasma glucose did not show altered incretin production in the first trimester of pregnancy. In contrast to type 2 diabetes, impaired incretin secretion does not seem to play a major role in the early development of GDM.

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.

The intestine and the microbiota in maternal glucose homeostasis during pregnancy

It is now well established that, beyond its role in nutrient processing and absorption, the intestine and its accompanying gut microbiome constitute a major site of immunological and endocrine regulation that mediates whole-body metabolism. Despite the growing field of host-microbe research, few studies explore what mechanisms govern this relationship in the context of pregnancy. During pregnancy, significant maternal metabolic adaptations are made to accommodate the additional energy demands of the developing fetus and to prevent adverse pregnancy outcomes. Recent data suggest that the maternal gut microbiota may play a role in these adaptations, but changes to maternal gut physiology and the underlying intestinal mechanisms remain unclear. In this review, we discuss selective aspects of intestinal physiology including the role of the incretin hormone, glucagon-like peptide 1 (GLP-1), and the role of the maternal gut microbiome in the maternal metabolic adaptations to pregnancy. Specifically, we discuss how bacterial components and metabolites could mediate the effects of the microbiota on host physiology, including nutrient absorption and GLP-1 secretion and action, and whether these mechanisms may change maternal insulin sensitivity and secretion during pregnancy. Finally, we discuss how these pathways could be altered in disease states during pregnancy including maternal obesity and diabetes.

Long-term functional alterations following prenatal GLP-1R activation

Evidence supporting the use of glucagon-like peptide-1 (GLP-1) analogues to pharmacologically treat disorders beyond type 2 diabetes and obesity is increasing. However, little is known about how activation of the GLP-1 receptor (GLP-1R) during pregnancy affects maternal and offspring outcomes. We treated female C57Bl/6 J mice prior to conception and throughout gestation with a long-lasting GLP-1R agonist, Exendin-4. While GLP-1R activation has significant effects on food and drug reward, depression, locomotor activity, and cognition in adults, we found few changes in these domains in exendin-4-exposed offspring. Repeated injections of Exendin-4 had minimal effects on the dams and may have enhanced maternal care. Offspring exposed to the drug weighed significantly more than their control counterparts during the preweaning period and demonstrated alterations in anxiety-like outcomes, which indicate a developmental role for GLP-1R modulation in the stress response that may be sex-specific.

Secondary analysis of gut hormone data from children with and without in utero exposure to gestational diabetes: Differences in the associations among ghrelin, GLP-1, and insulin secretion

BACKGROUND

Intrauterine exposure to gestational diabetes mellitus (GDM) increases risk for type 2 diabetes (T2D). Ghrelin and GLP-1 have opposite functions in nutritional homeostasis and are associated with insulin secretion, but it is not known if individuals exposed to GDM exhibit dysregulation in these associations.

OBJECTIVE

Test the hypothesis that children exposed to GDM in utero will exhibit dysregulation among ghrelin, GLP-1, and C-peptide (reflecting insulin secretion).

METHODS

Data from N = 43 children aged 5 to 10 years were included in this secondary analysis of ghrelin, GLP-1, and C-peptide response to a liquid meal test. Repeated measures mixed model analyses were used to measure associations among hormones.

RESULTS

The association of ghrelin and GLP-1 was moderated by GDM group (P < .01), such that ghrelin was inversely associated with GLP-1 in children without GDM exposure, but not for those exposed to GDM. GLP-1 was positively associated with C-peptide in both groups, but the association was stronger in those exposed to GDM (estimate = 1.06 vs 1.01).

CONCLUSIONS

Differences in the associations among ghrelin, GLP-1, and C-peptide displayed here suggest novel lines of research about whether the regulation of gut hormones and insulin secretion contribute to obesity and risk for T2D in children exposed to GDM.

The effect of dipeptidyl peptidase-4 inhibitor and glucagon-like peptide-1 receptor agonist in gestational diabetes mellitus: a systematic review

Gestational diabetes mellitus (GDM) is the most common complication in pregnancy and affects 13% pregnant women around the world. GDM has both short-term and long-term negative effect on mother and offspring. Dipeptidyl peptidase-4 (DPP-4) inhibitor and glucagon-like peptide-1 receptor agonist (GLP-1 Ra) have shown many extra-benefits in diabetes patients, and may be a promising choice to GDM. Here, we conducted a systematic review of randomized controlled trials to investigate the effect of DPP-4 inhibitor and GLP-1 Ra in GDM. This project was conducted based on the Preferred Reporting Items for Systematic Reviews and Meta Analyses (PRISMA) statement. We searched PubMed, EMBASE and Cochrane library up to November 8 2019 for eligible trials. A total of 982 records were identified and 4 trials (516 participants) met the criteria in the end. The results suggested that DPP-4 inhibitor and GLP-1 Ra can reduce the rate of developing postpartum diabetes, help to normalization of blood glucose and improve insulin resistance and β-cell function. Although the treatments showed beneficial effects in GDM patients, but the present data could not prove it use in GDM. Further clinical trials will be needed.

Postpartum treatment with liraglutide in combination with metformin versus metformin monotherapy to improve metabolic status and reduce body weight in overweight/obese women with recent gestational diabetes: A double-blind, randomized, placebo-controlled study

BACKGROUND

Gestational diabetes (GDM) imparts a high risk of developing diabetes postpartum. Insulin resistance appears to be the major contributor. Liraglutide, a glucagon-like peptide-1 analogue, improves peripheral glucose disposal and reduces body weight. We evaluated whether liraglutide in combination with metformin (MET-LIRA) is more effective than metformin monotherapy (MET-P) in improving insulin action and reducing body weight in overweight prior GDM (pGDM) women.

METHODS

Women (n = 153; body mass index (BMI) ≥25 kg/m²; 18-45 y; GDM within 12 months) with metabolic abnormalities were randomized to MET-LIRA (MET-2000 mg, LIRA 1.8 mg SC QD) or MET-P (MET-2000 mg, Placebo QD). Study visits at baseline, 36-40, 56-60 and 80-84 weeks included body weight (BW), BMI, waist circumference and waist-to-height ratio measures. Oral glucose tolerance tests (OGTTs) were performed to assess glycemia, mean blood glucose (MBG), lipids, and compute insulin sensitivity and secretion measures.

FINDINGS

Seventy-two (47%) participants completed the study. MET-LIRA therapy was significantly better in improving MBG and insulin sensitivity indices [SI_OGTT MET-LIRA from 4.6 (3.2) to 5.9 (2.9) vs. MET-P 5.5 (3.0) to 5.4 (3.2)] and reducing BW and central adiposity [BMI MET-LIRA from 37.2 (8.3) to 33.8 (5.2) vs MET-P 33.8(5.2) to 32.8(6)]. MET-LIRA therapy but not MET-P decreased triglycerides (TRG) and TRG/high density lipoprotein cholesterol (HDL-C) ratios.

INTERPRETATION

MET-LIRA treatment demonstrated superior efficacy in correcting the metabolic status of pGDM women over 84 weeks of therapy. The addition of liraglutide to metformin therapy resulted in a more dramatic decrease in BW and central adiposity than metformin alone.

FUNDATION

Supported by an unrestricted investigator initiated grant from Novo Nordisk, Inc. awarded to K.E.H.

MEETING PRESENTATION

The results from preliminary analyses of this study were presented at 76th meeting of the American Diabetes Association, June 10-14, 2016 New Orleans, LA, and 77th meeting of the American Diabetes Association, June 9-12, 2017San Diego, CA.

Perinatal Undernutrition, Metabolic Hormones, and Lung Development

Maternal and perinatal undernutrition affects the lung development of litters and it may produce long-lasting alterations in respiratory health. This can be demonstrated using animal models and epidemiological studies. During pregnancy, maternal diet controls lung development by direct and indirect mechanisms. For sure, food intake and caloric restriction directly influence the whole body maturation and the lung. In addition, the maternal food intake during pregnancy controls mother, placenta, and fetal endocrine systems that regulate nutrient uptake and distribution to the fetus and pulmonary tissue development. There are several hormones involved in metabolic regulations, which may play an essential role in lung development during pregnancy. This review focuses on the effect of metabolic hormones in lung development and in how undernutrition alters the hormonal environment during pregnancy to disrupt normal lung maturation. We explore the role of GLP-1, ghrelin, and leptin, and also retinoids and cholecalciferol as hormones synthetized from diet precursors. Finally, we also address how metabolic hormones altered during pregnancy may affect lung pathophysiology in the adulthood.