The relationship of serum AGE levels in diabetic mothers with adverse fetal outcome

Possible effects of dietary advanced glycation end products on maternal and fetal health: a review

Excessive accumulation of advanced glycation end products (AGEs) in the body has been associated with many adverse health conditions. The common point of the pathologies associated at this point is oxidative stress and inflammation. Pregnancy is an important period in which many physiological, psychological, and biological changes are experienced. Along with the physiological changes that occur during this period, the mother maintaining an AGE-rich diet may cause an increase in the body's AGE pool and may increase oxidative stress and inflammation, as seen in healthy individuals. Studies have reported the negative effects of maternal AGE levels on maternal and fetal health during pregnancy. Although gestational diabetes, preeclampsia, endothelial dysfunction, and pelvic diseases constitute maternal complications, a number of pathological conditions such as intrauterine growth retardation, premature birth, neural tube defect, neurobehavioral developmental disorders, fetal death, and neonatal asphyxia constitute fetal complications. It is thought that the mechanisms of these complications have not been confirmed yet and more clinical studies are needed on this subject. The possible effects of dietary AGE levels during pregnancy on maternal and fetal health are examined in this review.

First trimester screening of serum advanced glycation end products levels of pregnant women who have risk factors for gestational diabetes and their obstetric outcomes: a preliminary case-control study

Advanced glycation end-products (AGE) are complex compounds formed by nonenzymatic glycosylation of proteins, nucleic acids, and lipids with glucose in the blood. We aimed to investigate whether there was a difference in first-trimester serum AGE levels of pregnant women with and without risk factors for gestational diabetes mellitus (GDM) and their obstetric outcomes. There were 44 women in study group who have risk factors for GDM and 44 as controls. Demographic features, serum AGE levels, adverse perinatal and neonatal outcomes were compared between groups. Five patients (11.4%) in the study group and one patient (2.3%) in the control group were diagnosed as GDM (p = .2). The serum AGE values were not statistically different between the study and control groups. There were no statistical differences between groups in terms of adverse perinatal and neonatal outcomes. However, in the group with adverse perinatal outcome (n = 25), AGE values were higher than the control group. The results of our preliminary study suggested that high-risk women for GDM did not have increased serum levels of AGE in the first trimester. Nevertheless, a high first-trimester serum AGE level was found to be associated with adverse perinatal outcomes. IMPACT STATEMENTWhat is already known on this subject? Advanced glycation end products (AGE) are markers that are associated with diabetes and its complications. For pregnant women, a high third trimester serum AGEs levels were found in women who had gestational diabetes.What do the results of this study add? The results of our study revealed that first trimester screening of serum AGE levels of women who had risk factors for gestational diabetes was not discriminate. Nevertheless, a high first trimester serum AGE levels was associated with adverse perinatal outcome.What are the implications of these findings for clinical practice and/or further research? Whether reducing exogenous sources of AGE (western-style diet, smoking) before pregnancy will be associated with better pregnancy outcomes should be investigated in future studies.

Early AGEing and metabolic diseases: is perinatal exposure to glycotoxins programming for adult-life metabolic syndrome?

Perinatal early nutritional disorders are critical for the developmental origins of health and disease. Glycotoxins, or advanced glycation end-products, and their precursors such as the methylglyoxal, which are formed endogenously and commonly found in processed foods and infant formulas, may be associated with acute and long-term metabolic disorders. Besides general aspects of glycotoxins, such as their endogenous production, exogenous sources, and their role in the development of metabolic syndrome, we discuss in this review the sources of perinatal exposure to glycotoxins and their involvement in metabolic programming mechanisms. The role of perinatal glycotoxin exposure in the onset of insulin resistance, central nervous system development, cardiovascular diseases, and early aging also are discussed, as are possible interventions that may prevent or reduce such effects.

The relationship between advanced glycation end products and gestational diabetes: A systematic review and meta-analysis

INTRODUCTION

Gestational Diabetes Mellitus (GDM) is a condition in which women without history of diabetes experience hyperglycemia during pregnancy, especially at the second and third trimesters. In women who have had GDM, an elevated body mass index (BMI) may have a substantial impact for persistent hyperglycemia in their lives after gestation. Beyond hyperglycemia, increased local oxidative stress directly promotes the formation of Advanced Glycation End-products (AGEs). Hence, this systematic review and meta-analysis was aimed to determine the relationship between the level of AGEs and/or related metabolic biomarkers with GDM.

METHODS

Literature search was carried out through visiting electronic databases, indexing services, and directories including PubMed/MEDLINE (Ovid®), EMBASE (Ovid®), google scholar and WorldCat to retrieve studies without time limit. Following screening and eligibility evaluation, relevant data were extracted from included studies and analyzed using Rev-Man 5.3 and STATA 15.0. Inverse variance method with random effects pooling model was used for the analysis of outcome measures at 95% confidence interval. Hedge's adjusted g statistics was applied to calculate the standardized mean difference (SMD) to consider the small sample bias. Besides, meta-regression, meta-influence, and publication bias analyses were conducted. The protocol has been registered on PROSPERO with ID: CRD42020173867.

RESULTS

A total of 16 original studies were included for the systematic review and meta-analysis. Compared with women with pregnant controls, the level of AGE was significantly higher in women with GDM (SMD [95% CI] = 2.26 [1.50‒3.02], Z = 5.83, P < 0.00001; I2 = 97%, P< 0.0001). The BMI was also significantly higher in women with GDM (SMD [95% CI] = 0.97 [0.33‒1.62], Z = 2.98, P = 0.003) compared to controls. Regarding specific and related metabolic biomarkers, there was higher level of HOMA-IR (SMD [95% CI] = 0.39 [0.22-0.55], Z = 4.65, P < 0.0001, after sensitivity analysis) and HbA1c (SMD [95% CI] = 0.58 [0.03‒1.12], Z = 2.07, P = 0.04, after sensitivity analysis) in gestational diabetic women. Subgroup analyses indicated that studies conducted in Asia and Europe, at third trimester of pregnancy and blood/plasma AGE samples showed a significant difference in AGE level among women with GDM compared to pregnant controls. What is more, meta-regression with the sample size (regression coefficient (Q) = -0.0092, P = 0.207) and year of publication (Q = 0.0035, P = 0.984) suggested that the covariates had no significant effect on the heterogeneity.

CONCLUSION

The study indicated that there was a strong relationship between AGE and GDM. Besides, the BMI and other specific biomarkers showed a significant difference between the two groups indicating the high risk of developing long-standing type 2 diabetes and its complications in gestational diabetic women. Early detection of these biomarkers may play a pivotal role in controlling postpartum diabetic complications.

Advanced glycation end products increased placental vascular permeability of human BeWo cells via RAGE/NF-kB signaling pathway

OBJECTIVE

This study aimed to investigate the mechanisms of advanced glycation end products (AGEs) on cell tight conjunction and placental vascular permeability in BeWo cells.

STUDY DESIGN

Monolayer permeability assay and transmission electron microscopy were employed to reveal the transformation of the placental vascular permeability and cell tight conjunction. Immunofluorescence, western blot and RT-qPCR were adopted to determine the protein and mRNA levels. Anti-RAGE and NF-kB inhibitor (PDTC) were used to inactivate the RAGE/NF-kB signaling pathway.

RESULTS

AGEs significantly decreased trans-epithelial electrical resistance (TEER), while increased paracellular permeability (P <  0.05). TEM showed that AGEs made cell junction loose. AGEs inhibited ZO-1 and Occludin expressions, while anti-RAGE or PDTC partially restored their levels. AGEs also significantly increased mRNA RAGE and NF-kB expressions in BeWo cells (P <  0.05), and their expressions were inhibited by anti-RAGEy or PDTC.

CONCLUSION

AGEs could reduce the expressions of ZO-1 and Occludin by activating RAGE/NF-kB signaling pathway, thus increasing placental vascular permeability.

Low molecular weight heparin (nadroparin) improves placental permeability in rats with gestational diabetes mellitus via reduction of tight junction factors

Placental structural abnormalities and dysfunction in those with gestational diabetes mellitus (GDM) can lead to increased placental permeability, which is in turn related to a poorer maternal and fetal prognosis. The present study sought to assess whether increased placental permeability in rats with GDM was accompanied by alterations in tight junction (TJ) factors and to evaluate the impact of low molecular weight heparin (LMWH) on these factors. The present study was conducted using pregnant female rats that were randomized into control, GDM and GDM + LMWH groups. Diabetes was induced via intraperitoneal administration of streptozotocin to rats in the GDM and GDM + LMWH groups, whereas rats in the GDM + LMWH group received daily subcutaneous LMWH starting on day 5 of pregnancy. On gestational day 16, all rats were sacrificed and Evans Blue (EB) assay was used to gauge vascular permeability based on EB dye leakage. Transmission electron microscopy was further used to assess TJ structures, and the TJ proteins zonular occludens-1 (ZO-1) and occludin (OCLN) were assessed using immunohistochemistry and western blotting. Blood samples were obtained from the abdominal aorta for ELISA measurements of advanced glycation end products (AGEs) concentrations, and placental receptor for AGEs (RAGE) and vascular endothelial growth factor (VEGF) expression was assessed using reverse transcription-quantitative PCR. In addition, western blotting was used to measure placental NF-κB. Compared with in the control group, EB leakage was markedly increased in GDM group rats; this was associated with reduced ZO-1 and OCLN expression. Conversely, LMWH attenuated this increase in placental permeability in rats with GDM and also mediated a partial recovery of ZO-1 and OCLN expression. Blood glucose and serum AGEs concentrations did not differ between the GDM and GDM + LMWH groups. Furthermore, LMWH treatment resulted in decreases in RAGE and VEGF mRNA expression levels, which were upregulated in the GDM group, whereas it had the opposite effect on the expression of NF-κB. In conclusion, GDM was associated with increased placental permeability and this may be linked with changes in TJs. LMWH intervention mediated protection against this GDM-associated shift in placental permeability via the RAGE/NF-κB pathway.

Role of VEGF165b/VEGFTOTAL ratio in gestational diabetes mellitus

Proper vascular function is important for well-being of mother and growing fetus. VEGF_TOTAL, and VEGF_165b levels and its vascular endothelial complications in gestational diabetes mellitus (GDM) together with the association of inflammation and advanced glycation end products (AGEs) are less studied. VEGF_165b/VEGF_TOTAL (VEGF RATIO) in GDM pregnant women was investigated in this study. Plasma VEGF_TOTAL was lower in GDM (17.68 ± 1.30 pg/mL) compared to non-GDM (25.69 ± 1.40 pg/mL). VEGF_165b, ICAM-1, and AGEs were higher in GDM (9.9 ± 1.4 pg/mL, 201.04 ± 7.85 µg/mL, and 10.40 ± 0.98 µg/mL, respectively) and lower in non-GDM (6.47 ± 0.70 pg/mL, 174.1 ± 7.11 µg/mL, and 4.71 ± 0.39 µg/mL, respectively). Compared to non GDM (0.25 ± 0.02), VEGF RATIO was higher in GDM (0.45 ± 0.04) and correlated with -ICAM-1 (r = 0.375, p < .001) and AGEs (r = 0.199, p < .05). Tertile stratification of VEGF RATIO implied that frequency of GDM increases with increasing tertiles of VEGF RATIO (p for trend <.001). Association of VEGF RATIO with GDM was significant even after adjusting for AGEs (OR = 1.279, CI = 1.118-1.462, p < .0010) but it lost its significance when adjusted for ICAM-1 (OR = 1.006, CI = 0.995-1.017, p = .308). VEGF RATIO plays an important role in GDM in association with vascular inflammation.

Skin Autofluorescence of Pregnant Women With Diabetes Predicts the Macrosomia of Their Children

Advanced glycation end products (AGEs) accumulated during long-term hyperglycemia are involved in diabetes complications and can be estimated by skin autofluorescence (sAF). During pregnancy, hyperglycemia exposes women to the risk of having a macrosomic newborn. The aim of this study was to determine whether sAF of women with diabetes during a singleton pregnancy could predict macrosomia in their newborns. Using an AGE Reader, we measured the sAF at the first visit of 343 women who were referred to our diabetology department during years 2011-2015. Thirty-nine women had pregestational diabetes, 95 early gestational diabetes mellitus (GDM), and 209 late GDM. Macrosomia was defined as birth weight ≥4,000 g and/or large for gestational age ≥90th percentile. Forty-six newborns were macrosomic. Their mothers had 11% higher sAF compared with other mothers: 2.03 ± 0.30 arbitrary units (AUs) vs. 1.80 ± 0.34 (P < 0.0001). Using multivariate logistic regression, the relation between sAF and macrosomia was significant (odds ratio 4.13 for 1-AU increase of sAF [95% CI 1.46-11.71]) after adjusting for several potential confounders. This relation remained significant after further adjustment for HbA_1c (among 263 women with available HbA_1c) and for women with GDM only. sAF of pregnant women with diabetes, a marker of long-term hyperglycemic exposure, predicts macrosomia in their newborns.

Changes in circulating levels of carboxymethyllysine, soluble receptor for advanced glycation end products (sRAGE), and inflammation markers in women during normal pregnancy

Objective: To determine the circulating levels of insulin, Nε-carboxymethyllysine (CML), soluble receptor for advanced glycation end products (sRAGE), and markers of inflammation and oxidative stress (OS) in maternal and umbilical cord blood in a cohort of healthy women with normal pregnancy.Methods: We conducted an observational longitudinal study in a group of women (n = 31; age range 18-39 years) with healthy pregnancy starting at 30 weeks of gestation and finishing at the time of delivery. We collected weight and height in the participants and their neonates and calculated body mass index (BMI). Blood from each patient was collected at 30th week of pregnancy and at delivery when a sample of cord blood was also obtained. Glucose, lipid profile, CML, sRAGE, malondialdehyde (MDA), tumor necrosis factor-α (TNF-α), highly sensitivity C-reactive protein (hsPCR), and insulin were determined. The study was approved by the University of Guanajuato Institutional Ethics Committee.Results: All pregnancies reached term (mean gestational time 38.9 ± 0.83 weeks) and there were no maternal complications. Mean age was 27.6 years. Lipid profile values were higher in the group compared with our values in nonpregnant women. During pregnancy, levels of insulin increased (p < .0006), CML (p < .0001) and sRAGE (p < .01) decreased, levels of MDA did not change, while those of TNF-α and hsPCR tended to increase. In the neonates, we found lower levels of CML (p < .003), hsPCR (p < .004), and insulin (p < .004) and higher levels of sRAGE (p < .013) and TNF-α (p < .022) compared to their mothers at delivery. In the total group, we found association of CML of the mother at baseline with the CML (p < .0006) and MDA (p < .002) in neonates, while maternal sRAGE at the end of pregnancy was associated with CML (p < .004) of their neonates.Conclusions: Our study confirms that normal pregnancy is accompanied by insulin resistance (IR) and significant increase in lipid profile, and demonstrates that circulating levels of CML and sRAGE decreased significantly at the end of pregnancy. The lack of association between the course of insulin levels and those of CML probably results from the predominant role of placental factors in the pathogenesis of IR in pregnancy. sRAGE levels in the neonates are markedly increased compared to their mothers suggesting a placental origin of this compound which may have a protective effect on the fetus since sRAGE restricts Advanced glycation end product (AGE) effects and may exert anti-inflammatory effects.

Phytate Decreases Formation of Advanced Glycation End-Products in Patients with Type II Diabetes: Randomized Crossover Trial

Myo-inositol hexaphosphate (phytate; IP6) is a natural compound that is abundant in cereals, legumes, and nuts and it has the ability to chelate metal cations. The binding of IP6 to transition metals suggests that it could be used for the treatment of metal-catalyzed protein glycation, which appears to trigger diabetes-related diseases. Our in vitro studies showed that IP6 reduced the formation of Fe3+-catalyzed advanced glycation end-products (AGEs). This led us to perform a randomized cross-over trial to investigate the impact of the daily consumption IP6 on protein glycation in patients with type 2 diabetes mellitus (T2DM; n = 33). Thus, we measured AGEs, glycated hemoglobin (HbA1c), several vascular risk factors, and urinary IP6 at baseline and at the end of the intervention period. Patients who consumed IP6 supplements for 3 months had lower levels of circulating AGEs and HbA1c than those who did not consume IP6. This is the first report to show that consumption of IP6 inhibits protein glycation in patients with T2DM. Considering that AGEs contribute to microvascular and macrovascular complications in T2DM, our data indicates that dietary supplementation with IP6 should be considered as a therapy to prevent the formation of AGEs and therefore, the development of diabetes-related diseases in patients with T2DM.

Influence of gestational diabetes on the activity of δ-aminolevulinate dehydratase and oxidative stress biomarkers

Objective: This study aimed to evaluate the activity of delta-aminolevulinate dehydratase (δ-ALA-D) and oxidative stress biomarkers in pregnant women with gestational diabetes mellitus (GDM), in order to demonstrate the involvement of oxidative stress in this condition, which presents pathophysiology still undetermined.

Methods: δ-ALA-D activity, lipid peroxidation estimated as the levels of thiobarbituric acid reactive substances (TBARS), protein (P-SH) and non-protein thiol (NP-SH) content, catalase (CAT) activity and concentration of vitamin C (VIT C) in samples of pregnant women with GDM (n = 48) and in healthy pregnant women (n = 30), who constituted the control group.

Results: The δ-ALA-D activity was significantly lower in pregnant women with GDM compared to controls, as well as levels of thiols, VIT C and CAT activity. Lipid peroxidation was higher in GDM group.

Discussion: The results suggest that the main factor for the increase in oxidative stress and reduced δ-ALA-D activity in diabetic pregnant women is gestational hyperglycemic environment, which changed the redox balance and interfered on mechanism of the δ-ALA-D activity in relation to normoglycemic pregnant women.

Insulin signalling and glucose transport in the ovary and ovarian function during the ovarian cycle

Data derived principally from peripheral tissues (fat, muscle and liver) show that insulin signals via diverse interconnecting intracellular pathways and that some of the major intersecting points (known as critical nodes) are the IRSs (insulin receptor substrates), PI3K (phosphoinositide kinase)/Akt and MAPK (mitogen-activated protein kinase). Most of these insulin pathways are probably also active in the ovary and their ability to interact with each other and also with follicle-stimulating hormone (FSH) and luteinizing hormone (LH) signalling pathways enables insulin to exert direct modulating influences on ovarian function. The present paper reviews the intracellular actions of insulin and the uptake of glucose by ovarian tissues (granulosa, theca and oocyte) during the oestrous/menstrual cycle of some rodent, primate and ruminant species. Insulin signals through diverse pathways and these are discussed with specific reference to follicular cell types (granulosa, theca and oocyte). The signalling pathways for FSH in granulosa cells and LH in granulosa and theca cells are summarized. The roles of glucose and of insulin-mediated uptake of glucose in folliculogenesis are discussed. It is suggested that glucose in addition to its well-established role of providing energy for cellular function may also have insulin-mediated signalling functions in ovarian cells, involving AMPK (AMP-dependent protein kinase) and/or hexosamine. Potential interactions of insulin signalling with FSH or LH signalling at critical nodes are identified and the available evidence for such interactions in ovarian cells is discussed. Finally the action of the insulin-sensitizing drugs metformin and the thiazolidinedione rosiglitazone on follicular cells is reviewed.

Serum Fluorescent Advanced Glycation End (F-AGE) products in gestational diabetes patients

Objectives

Advanced glycation end products (AGEs) are involved in the pathogenesis and complications of diabetes mellitus (DM). Gestational DM (GDM) is characterized by increased glycemia and oxidative stress, which are factors associated with high serum AGE concentrations. The aim of this study was to evaluate the utility of a serum fluorescence AGE (F-AGE) method as a screening tool for gestational diabetes.

Subjects and methods

Serum samples from 225 GDM patients and 217 healthy pregnant women (healthy controls) were diluted 50-fold in phosphate-buffered saline, and the AGEs were estimated by fluorometric analysis (λEx 350 nm/ λEm 440 nm).

Results

No significant (P > 0.05) differences in AGE concentrations, expressed in Arbitrary Units (UA/mL × 104), were observed in the women with GDM or in the healthy controls. Furthermore, F-AGE concentrations did not change significantly during the pregnancy (12-32 weeks of gestation). Only the GDM group had a positive correlation (r = 0.421; P < 0.001) between F-AGEs and serum creatinine concentrations.

Conclusion

It was not possible to distinguish women with gestational diabetes from the healthy controls on the basis of serum F-AGE concentrations.

Dysfunctional protection against advanced glycation due to thiamine metabolism abnormalities in gestational diabetes

While the pathogenic role of dicarbonyl stress and accelerated formation of advanced glycation end products (AGEs) to glucose intolerance and to the development of diabetic complications is well established, little is known about these processes in gestational diabetes mellitus (GDM), a condition pathogenically quite similar to type 2 diabetes. The aims of the present study were (i) to determine plasma thiamine and erythrocyte thiamine diphosphate (TDP) and transketolase (TKT) activity in pregnant women with and without GDM, (ii) to assess relationships between thiamine metabolism parameters and selected clinical, biochemical and anthropometric characteristics and, finally, (iii) to analyse relationship between variability in the genes involved in the regulation of transmembrane thiamine transport (i.e. SLC19A2 and SLC19A3) and relevant parameters of thiamine metabolism. We found significantly lower plasma BMI adjusted thiamine in women with GDM (P = 0.002, Mann-Whitney) while levels of erythrocyte TDP (an active TKT cofactor) in mid-trimester were significantly higher in GDM compared to controls (P = 0.04, Mann-Whitney). However, mid-gestational TKT activity - reflecting pentose phosphate pathway activity - did not differ between the two groups (P > 0.05, Mann-Whitney). Furthermore, we ascertained significant associations of postpartum TKT activity with SNPs SLC19A2 rs6656822 and SLC19A3 rs7567984 (P = 0.03 and P = 0.007, resp., Kruskal-Wallis). Our findings of increased thiamine delivery to the cells without concomitant increase of TKT activity in women with GDM therefore indicate possible pathogenic role of thiamine mishandling in GDM. Further studies are needed to determine its contribution to maternal and/or neonatal morbidity.

Protective effect of sRAGE on fetal development in pregnant rats with gestational diabetes mellitus

To investigate the protective effect of secretory receptor for advanced glycation endproducts (sRAGE) on the fetal development using rat model of gestational diabetes mellitus (GDM). The model of pregnant rats with intrauterine hyperglycemia was established by intraperitoneal injection of 25 mg/kg streptozotocin (STZ). Rats with established GDM were randomly grouped, and the pregnant rats in the experimental group were subsequently injected with recombinant sRAGE protein (5 mg/kg, in 0.2 mL PBS) at tail vein every 24 h, while the rats in control group were injected with the same dosage of albumin solution. Blood glucose, serum levels of advanced glycation endproducts (AGEs), and levels of RAGE protein in brain and heart tissues of pregnant rats were measured at 3, 13, and 19 days postconception. At 19 days fetuses were delivered by cesarean section, number of fetuses, their weight and placental weights were recorded, and fetal malformations and defects were analyzed visually and pathologically. The expression level of RAGE, NOX2, MCP-1, p65, VCAM-1, and VEGF mRNA in placenta was evaluated by real-time PCR. p65 protein localization was detected by immunohistochemistry in fetal brain and heart tissue sections. We analyzed the correlation between AGEs and RAGE level and the development of fetal rats, and the protective effect of blocking AGEs-RAGE pathway on the fetal development in the rat model of GDM was investigated. (1) The concentration of blood glucose and AGEs in serum of pregnant rats with GDM was significantly higher than in control group (p < 0.05), with strong correlation between blood glucose and levels of AGEs (r = 0.693, p < 0.05). (2) While both the number of fetuses and placental wet weight in pregnant rat model of GDM were similar to control group, pups from GDM group exhibited higher incidence of developmental abnormalities and higher average weight (p < 0.05). sRAGE treatment slightly but not significantly reduced the probability of the fetal developmental defects, as compared to GDM group. (3) p65, a part of the NF-kB heterodimeric complex, was localized to cell nuclei in the fetal tissues of pups delivered by GDM rats, while sRAGE treatment partially restored cytoplasmic localization of p65, similarly to control tissues. Increased incidence of fetal developmental defects observed in offsprings of pregnant rats with GDM had significant correlation with the level of AGEs in serum of pregnant rats and expression levels of RAGE protein in tissues. GDM resulted in upregulation of mRNA expression of several pro-inflammatory and ROS-inducing genes in placental tissues of pregnant rats. Elevated blood glucose, serum AGEs levels, and increased gene expression are attenuated by intravenous sRAGE treatment. sRAGE appears to reduce the activity of NF-κB in fetal tissues, thus potentially having a protective effect on fetal development.

Thiol/disulfide homeostasis in predicting adverse perinatal outcomes at 24-28 weeks of pregnancy in gestational diabetes

OBJECTIVE

The main aim of this study was to investigate thiol/disulfide homeostasis at 24-28 weeks of pregnancy and to evaluate whether it is predictive for adverse perinatal outcomes or not in gestational diabetes mellitus (GDM).

METHODS

A total of 110 pregnant women at 24-28 weeks of pregnancy (74 GDM patients and 36 age- and BMI-matched healthy pregnant women) were enrolled in this prospective case-control study. Thiol/disulfide homeostasis was evaluated with a novel spectrophotometric method to determine if there is an association with adverse perinatal outcomes in GDM, by using logistic regression analysis.

RESULTS

GDM patients, with decreased native thiol levels at 24-28 weeks (OR: 4.890, 95% CI: 1.355-5.764, p = 0.015) and with higher pre-pregnancy BMI (OR: 1.280, 95% CI: 1.072-1.528, p = 0.006), were found to be at increased risk of adverse perinatal outcomes in GDM. There were no statistically significant differences in thiol/disulfide homeostasis between diet- and insulin-treated GDM subgroups. Additionally, 1-h and 2-h glucose levels on 100 g OGTT were found to be predictive for the insulin need in achieving good glycemic control in GDM (OR: 1.022, 95% CI: 1.005-1.038, p = 0.010 and OR: 1.019, 95% CI: 1.004-1.035, p = 0.015).

CONCLUSIONS

GDM patients, with decreased native thiol levels at 24-28 weeks of pregnancy and with higher pre-pregnancy BMI, have an increased risk of possible adverse perinatal outcomes. Also, increased 1-h and 2-h glucose levels on 100 g OGTT can predict the need for insulin treatment for GDM.

Is skin autofluorescence a marker of metabolic memory in pregnant women with diabetes?

AIM

To determine whether skin autofluorescence can help to detect those who have previously had abnormal glucose levels among women referred for diabetes during pregnancy.

METHODS

Using an advanced glycation end product reader (AGE Reader(tm) (;) DiagnOptics BV, Groningen, the Netherlands), we measured forearm skin autofluorescence at 24-30 weeks of gestation in all women who were referred to our Nutrition Diabetology unit for diabetes during pregnancy.

RESULTS

The study included 230 women (200 with gestational diabetes and 30 with pre-gestational diabetes, of whom 21 had Type 1 and nine had Type 2 diabetes) and a reference group of 22 normoglycaemic non-pregnant women. Skin autofluorescence was significantly higher in women with pre-gestational diabetes (1.97 ± 0.44 arbitary units) compared with gestational diabetes (1.77 ± 0.32 arbitary units; P = 0.003) and lower in the reference group (1.60 ± 0.32 arbitary units; P = 0.009 vs all pregnant women). Among women with gestational diabetes, 71 had a history of hyperglycaemia (i.e. gestational diabetes or macrosomia in a previous pregnancy or discovery of diabetes before 24th gestational week in the present pregnancy). These women had higher levels of skin autofluorescence (1.83 ± 0.35 arbitary units) than women with gestational diabetes without previous history of hyperglycaemia (1.73 ± 0.30 arbitary units; P = 0.04, non-significant, adjusted for age). Skin autofluorescence increased with the number of criteria present for previous hyperglycaemia (P for trend = 0.008) and was significantly associated with having two or three criteria for hyperglycaemia after adjusting for age (P = 0.02).

CONCLUSIONS

Skin autofluorescence could reflect previous long-term hyperglycaemia in pregnant women, and could therefore be a marker of metabolic memory.

Accumulation of advanced glycation end products in the rabbit blastocyst under maternal diabetes

Diabetes mellitus (DM) during pregnancy is one of the leading causes of perinatal morbidity and birth defects. The mechanism by which maternal hyperglycemia, the major teratogenic factor, induces embryonic malformations remains unclear. Advanced glycation end products (AGEs) are known to accumulate during the course of DM and contribute to the development of diabetic complications. Employing a diabetic rabbit model, we investigated the influence of maternal hyperglycemia during the preimplantation period on AGE formation (pentosidine, argpyrimidine, and Nε-carboxymethyllysine (CML)) in the reproductive tract and the embryo itself. As a consequence of type 1 DM, the AGE levels in blood plasma increased up to 50%, correlating closely with an AGE accumulation in the endometrium of diabetic females. Embryos from diabetic mothers had increased protein-bound CML levels and showed enhanced fluorescent signals for AGE-specific fluorescence in the blastocyst cavity fluid (BCF). The quantification of CML by HPLC–mass spectrometry (MS/MS) showed a higher amount of soluble CML in the BCF of blastocysts from diabetic rabbits (0.26±0.05 μmol/l) compared with controls (0.18±0.02 μmol/l). The high amount of AGEs in blastocysts from diabetic mothers correlates positively with an increased AGER (receptor for AGE (RAGE)) mRNA expression. Our study gives alarming insights into the consequences of poorly controlled maternal diabetes for AGE formation in the embryo. Maternal hyperglycemia during the preimplantation period is correlated with an increase in AGE formation in the uterine environment and the embryo itself. This may influence the development of the embryo through increased AGE-mediated cellular stress by RAGEs.

AGEs, contributors to placental bed vascular changes leading to preeclampsia

Glycation of proteins or other biomolecules and their further long-term degradation result in the formation of advanced glycation end products, AGEs. AGEs and other ligands interact with their receptors, RAGEs, localized to a variety of tissues, but mainly in endothelium and vascular wall cells. This interaction triggers diverse signaling pathways that converge on the activation of NF-κB and the initiation of a local inflammatory reaction that, when prolonged, results in dysfunctional features. Preeclampsia is a serious vascular disorder centred at the placenta-uterine interface, the placental bed, but the condition extends to the mother's circulation. RAGEs have notorious expression in the placental bed tissues along pregnancy but, in addition, RAGEs and their ligands are expressed in the fetal membranes and are found in the amniotic fluid and the mother's serum. Disorders complicating pregnancies and having an important vascular involvement, as preeclampsia and diabetes mellitus, have additional enhanced AGE/RAGE expression variation. This indicates that for their assessment, the assay of RAGEs or their ligands may become useful diagnostic or prognostic procedures.

Advanced glycation end products, measured as skin autofluorescence, at diagnosis in gestational diabetes mellitus compared with normal pregnancy

BACKGROUND

Advanced glycation end products (AGEs) are tissue proteins that accumulate with age and in diabetes mellitus (DM). AGEs can be measured by the AGE-Reader (DiagnOptics Technologies BV, Groningen, The Netherlands), which measures skin autofluorescence (SAF). SAF has been suggested as a measure to screen for undiagnosed DM or impaired glucose tolerance. SAF has never been investigated in gestational DM (GDM). Therefore we compared SAF at diagnosis in GDM patients with normal pregnancy. If SAF is elevated in GDM, future research could focus on the possible use of the AGE-Reader as a screening method for GDM.

METHODS

In this monocenter observational study SAF was measured in 60 GDM patients at diagnosis and 44 pregnant women without diabetes.

RESULTS

SAF did not differ between GDM at diagnosis (mean [SD], 1.74 [0.31] arbitrary units) and normal pregnancy (1.76 [0.32] arbitrary units). SAF was lower in white European patients than in patients with other ethnicity.

CONCLUSIONS

This first study of tissue AGE accumulation in pregnancy shows no differences in SAF between women with GDM at diagnosis and normal pregnancy. This is most likely due to mild severity and short duration of hyperglycemia in GDM at diagnosis, but it does not exclude potential differences in SAF later in pregnancy. However, the fact that no differences are detected at diagnosis makes it unlikely that the AGE-Reader can be developed as a screening method for GDM in the future. Furthermore, we found that ethnicity should be taken into account when measuring SAF.