CTX (crosslaps) rather than osteopontin is associated with disturbed glucose metabolism in gestational diabetes

The diagnostic indicators of gestational diabetes mellitus from second trimester to birth: a systematic review

BACKGROUND

Gestational diabetes mellitus (GDM) is glucose intolerance first recognised during pregnancy. Both modalities and thresholds of the GDM diagnostic test, the Oral Glucose Tolerance Test (OGTT), have varied widely over time and among countries. Additionally, OGTT limitations include inconsistency, poor patient tolerability, and questionable diagnostic reliability. Many biological parameters have been reported to be modified by GDM and could potentially be used as diagnostic indicators. This study aimed to 1) systematically explore biomarkers reported in the literature as differentiating GDM from healthy pregnancies 2) screen those indicators assessed against OGTT to propose OGTT alternatives.

MAIN BODY

A systematic review of GDM diagnostic indicators was performed according to PRISMA guidelines (PROSPERO registration CRD42020145499). Inclusion criteria were full-text, comprehensible English-language articles published January 2009-January 2021, where a biomarker (from blood, ultrasound, amniotic fluid, placenta) was compared between GDM and normal glucose tolerance (NGT) women from the second trimester onward to immediately postpartum. GDM diagnostic method had to be clearly specified, and the number of patients per study higher than 30 in total or 15 per group. Results were synthesised by biomarkers.

RESULTS

Of 13,133 studies identified in initial screening, 174 studies (135,801 participants) were included. One hundred and twenty-nine studies described blood analytes, one amniotic fluid analytes, 27 ultrasound features, 17 post-natal features. Among the biomarkers evaluated in exploratory studies, Adiponectin, AFABP, Betatrophin, CRP, Cystatin-C, Delta-Neutrophil Index, GGT, TNF-A were those demonstrating statistically and clinically significant differences in substantial cohorts of patients (> 500). Regarding biomarkers assessed versus OGTT (i.e. potential OGTT alternatives) most promising were Leptin > 48.5 ng/ml, Ficolin3/adiponectin ratio ≥ 1.06, Chemerin/FABP > 0.71, and Ultrasound Gestational Diabetes Score > 4. These all demonstrated sensitivity and specificity > 80% in adequate sample sizes (> / = 100).

CONCLUSIONS

Numerous biomarkers may differentiate GDM from normoglycaemic pregnancy. Given the limitations of the OGTT and the lack of a gold standard for GDM diagnosis, advanced phase studies are needed to triangulate the most promising biomarkers. Further studies are also recommended to assess the sensitivity and specificity of promising biomarkers not yet assessed against OGTT.

TRIAL REGISTRATION

PROSPERO registration number CRD42020145499.

Associations between bone and energy metabolism in cows fed diets differing in level of dietary cation-anion difference and supplemented with cholecalciferol or calcidiol

Bone-derived hormones play an important role in metabolism. This study examined the hypothesis that interactions between bone and energy metabolism, particularly those involving osteocalcin, are present in dairy cattle and have feedback mechanisms over time. Associations between metabolites in blood were examined in 32 Holstein cows blocked by parity and milk yield and randomly allocated to diets containing either 0.27 mg/kg dry matter (DM) calcidiol or cholecalciferol for an anticipated intake of 3 mg/d (120,000 IU/d) at 11 kg of DM, and positive (+130 mEq/kg DM) or negative (-130 mEq/kg DM) dietary cation-anion difference (DCAD) from 252 d of gestation to calving. Blood was sampled every 3 d, from 9 d prepartum to 30 d postpartum, and plasma concentrations of vitamin D₃, 25-hydroxyvitamin D₃, adiponectin, C-telopeptide of type 1 collagen (CTX1), glucose, insulin-like growth factor 1 (IGF1), insulin, undercarboxylated osteocalcin (uOC), and carboxylated osteocalcin (cOC) were determined. Feeding calcidiol compared with cholecalciferol increased plasma concentrations of 25-hydroxyvitamin D₃ pre- (264.2 ± 8.0 vs. 61.3 ± 8.0 ng/mL) and postpartum (170.8 ± 6.2 vs. 51.3 ± 6.2 ng/mL) but decreased concentrations of vitamin D₃ pre- (1.2 ± 0.6 vs. 14.5 ± 0.6 ng/mL) and postpartum (1.9 ± 0.4 vs. 3.2 ± 0.6 ng/mL). Prepartum, cows fed the negative DCAD diet had reduced concentrations of vitamin D₃ and glucose compared with cows fed a positive DCAD. The combination of negative DCAD and cholecalciferol reduced IGF1 concentrations prepartum. The DCAD treatment had no effect on postpartum concentrations of metabolites. Nulliparous cows had increased concentrations of OC, CTX1, IGF1, glucose, and insulin compared with parous cows. Time series analysis identified associations between metabolites on the same day and over 3-d lags up to ±9 d that suggest feedback between 25-hydroxyvitamin D₃ and vitamin D₃ in the negative lags, indicating that 25-hydroxyvitamin D₃ may exert feedback on vitamin D₃ but not vice versa. We found evidence of a feedback mechanism between vitamin D₃ and IGF1, with positive effect size (ES) on the same day and 3 d later, and negative ES 9 d later, that was more evident in cholecalciferol-fed cows. This suggests an important role of IGF1 in integrating bone metabolism with energy and protein metabolic pathways. Evidence of feedback was found between uOC and particularly cOC with IGF1, with positive ES on the same day but negative ES 6 d before and 6 d after. An association between uOC or cOC and IGF1 has not been previously identified in cattle and suggests that both uOC and cOC may have marked biological activity. Associations between OC and insulin identified in mice were not observed herein, although associations between OC and glucose were similar to those between IGF1 and glucose, supporting associations between glucose, OC, and IGF1. We provide further statistical evidence of crosstalk between vitamin D compounds, bone hormones, and energy metabolism in cattle. In particular, associations between uOC or cOC and IGF1 may provide links between prepartum diets and observations of prolonged increases in milk production and allow better control of peripartum metabolism.

Osteocalcin Serum Levels in Gestational Diabetes Mellitus and Their Intrinsic and Extrinsic Determinants: Systematic Review and Meta-Analysis

BACKGROUND

Undercarboxylated osteocalcin (ucOC) increases insulin release and insulin resistance in mice. In humans, evidence is scarce but a correlation of ucOC and total osteocalcin (tOC) with glycemic status markers has been demonstrated. The relationship of ucOC and tOC with gestational diabetes mellitus (GDM) has been even less characterized.

OBJECTIVE

To assess the mean difference of tOC and ucOC serum concentrations among nondiabetic pregnant women and women diagnosed as GDM in the second trimester of pregnancy and to determine the possible intrinsic and extrinsic contributors to this difference.

METHODS

A systematic search was performed to identify relevant studies published in English and Spanish using PubMed, SCOPUS, ISI Web of Knowledge, and PROSPERO database for meta-analysis. Observational studies measuring mean serum levels of osteocalcin among GDM, with at least 10 subjects analyzed in each group were selected. Mean difference (MD) by random effects model was used. Heterogeneity between studies was assessed using Cochran's Q, H, and I ² statistics.

RESULTS

From 38 selected studies, 5 were retained for analysis for a total of 1119 pregnant women. Serum concentrations of tOC were not significantly different among women with GDM and nondiabetic pregnant controls (MD: 1.56; 95% CI: -0.70 to 3.82; p = 0.175). Meanwhile, ucOC serum levels were significantly higher among women with GDM (MD: 1.17; 95% CI: 0.24 to 2.11; p = 0.013). The only factor influencing tOC was the UV index, showing a reduction in mean difference between GDM and controls when exposed to higher concentrations of UV rays.

CONCLUSIONS

This meta-analysis provides evidence to support the use of ucOC as a potential marker for GDM rather than tOC, yielding very little variability among studies and no difference among methods or brands used for its analysis.

Association of bone turnover markers with glucose metabolism in Chinese population

The association between type 2 diabetes (T2DM) and bone metabolism has been discussed previously but is controversial. In this study we aimed to evaluate the association of bone turnover markers with glucose metabolism in Chinese population, in which 919 males and 4171 postmenopausal females in a region of Shanghai were recruited. Anthropometric and biochemical traits related to glucose and bone metabolism were analyzed. Participants were classified according to their glucose tolerance as normal glucose tolerance (NGT), impaired glucose regulation (IGR) or T2DM. Males and females were analyzed separately, and then associations between bone turnover markers (BTMs) and glucose metabolism were evaluated. The results showed that in females, the serum levels of N-terminal osteocalcin (N-MID), N-terminal procollagen of type I collagen (PINP) and β-cross-linked C-telopeptide of type I collagen (β-CTX) were significantly decreased in the T2DM group compared to the NGT group (P<0.01). When age, body mass index, serum lipids, fat percentage, visceral fat area, subcutaneous fat area, anti-diabetic medicines, PINP, N-MID and β-CTX were included in one logistic model, N-MID (OR [95% CI]: 0.954 [0.932; 0.976]; P=0.0001) was significantly associated with T2DM in females. In females, N-MID was associated with insulin sensitivity and HOMA-β. PINP was significantly associated with HOMA-β, GUTT-ISI, Stumvoll first-phase insulin secretion index (STU-1) and Stumvoll second-phase insulin secretion index (STU-2), but β-CTX was associated only with HOMA-β (β±SE: 0.1331±0.0311; P=1.95×10^-5) and GUTT-ISI (β±SE: 0.0727±0.0229; P=0.0015). In males, N-MID was significantly correlated with HOMA-β (β±SE: 0.3439±0.0633; P=7.75×10^-8), GUTT-ISI (β±SE: 0.1601±0.0531; P=0.0027) and STU-1 (β±SE: 0.2529±0.1033; P=0.0146). Significant associations were also detected between β-CTX and HOMA-β (β±SE: 0.2736±0.0812; P=0.0009). This study reveals that BTMs are highly associated with T2DM, insulin sensitivity and beta cell function in both Chinese males and postmenopausal females.

Polycystic ovary syndrome is associated with increased osteopontin levels

OBJECTIVE

Osteopontin (OPN) is a multi-functional secreted glycoprotein that plays a crucial role in glucose metabolism and inflammatory process. Growing evidence suggests that there is a link between OPN and ovarian function. However, no such link has yet been found for OPN in polycystic ovary syndrome (PCOS). Our aim was to ascertain whether circulating OPN levels are altered in women with PCOS and to determine whether OPN levels differ between the follicular phase and mid-cycle of the menstrual cycle in eumenorrheic women.

DESIGN AND METHODS

In total, 150 women with PCOS and 150 age- and BMI-matched controls without PCOS were recruited for this prospective observational study. OPN levels were measured using ELISA. Metabolic parameters were also determined.

RESULTS

Circulating OPN levels were significantly elevated in PCOS women compared with controls (69.12±31.59  ng/ml vs 42.66±21.28  ng/ml; P<0.001). OPN levels were significantly higher at mid-cycle than in the follicular phase in eumenorrheic women. OPN was positively correlated with BMI, homeostasis model assessment of insulin resistance (HOMA-IR), free testosterone, and high sensitivity C-reactive protein (hs-CRP). Multivariate logistic regression analyses revealed that the odds ratio (OR) for PCOS was 3.64 for patients in the highest quartile of OPN compared with those in the lowest quartile (OR=3.64; 95% CI=2.42-5.57; P=0.011). Our findings indicate that BMI, HOMA-IR, hs-CRP, and free testosterone are independent factors influencing serum OPN levels and that OPN is an independent predictor for HOMA-IR.

CONCLUSION

PCOS is associated with increased OPN levels.

First trimester screening for gestational diabetes mellitus by maternal factors and markers of inflammation

OBJECTIVE

To examine the potential role of maternal serum levels of tumor necrosis factor-α (TNF-α) and high sensitivity C-reactive protein (Hs-CRP) in the first trimester of pregnancy in the prediction of gestational diabetes mellitus (GDM).

METHODS

Maternal serum TNF-α and Hs-CRP concentrations were measured in a case-control study of singleton pregnancies at 11-13 weeks' gestation, which included 200 cases that subsequently developed GDM and 800 unaffected controls. Measured levels of TNF-α and Hs-CRP were expressed as multiples of the median (MoM) after adjustment for maternal characteristics and history. The performance of screening for GDM by maternal factors and MoM values of TNF-α and Hs-CRP was evaluated by the area under the receiver operating characteristic curves (AUROC).

RESULTS

In the GDM group, compared to the normal group, the median TNF-α was significantly increased (1.303 MoM, interquartile range [IQR] 1.151-1.475 vs. 1.0 MoM, IQR 0.940-1.064; p=0.031) and the median Hs-CRP was not significantly different (1.113 MoM, IQR 0.990-1.250 vs. 1.0 MoM, IQR 0.943-1.060; p=0.084). In the prediction of GDM, the AUROC for maternal characteristics with TNF-α or Hs-CRP was not significantly different than the AUROC for maternal characteristics alone (p=0.5055 and p=0.2197, respectively).

CONCLUSIONS

In pregnancies that develop GDM there is no evidence of an inflammatory response at 11-13 weeks' gestation and the levels of serum TNF-α and Hs-CRP are not useful in first-trimester screening for GDM.

Maternal serum osteocalcin at 11-14 weeks of gestation in gestational diabetes mellitus

BACKGROUND

Recent studies support that osteocalcin (OC), apart from its skeletal role, is implicated in glucose homoeostasis. Aims of this study were to examine the first-trimester maternal serum concentrations of OC in pregnancies that developed gestational diabetes mellitus (GDM) and to create a first-trimester prediction model for GDM.

DESIGN

Case-control study in a prospective cohort of pregnant women. Maternal serum levels of OC were measured in 40 cases that developed GDM and 94 unaffected controls. First-trimester biophysical parameters, biochemical indices, maternal-pregnancy characteristics, and OC concentrations were assessed in relation to GDM occurrence.

RESULTS

In the GDM group, first-trimester OC serum levels were increased compared to the control group (mean = 8·81 ng/mL, SD = 2·59 vs. mean = 7·34 ng/ml, SD = 3·04, P = 0·0058). Osteocalcin was independent of first-trimester biophysical and biochemical indices. Osteocalcin alone (OR = 1·21, CI: 1·02-1·43, P = 0·023) was a significant predictor of GDM [Model R(2) = 0·04, area under the curve (AUC) = 0·61, CI: 0·55-0·72, P < 0·001]. The combination of maternal and pregnancy characteristics with OC resulted in an improved prediction model for GDM (Model R(2) = 0·21, AUC = 0·80, CI: 0·71-0·88, P < 0·001). The combined model yields a sensitivity of 72·2% for 25% false-positive rate.

CONCLUSIONS

First-trimester maternal serum levels of OC are increased in GDM pregnancies. Osteocalcin combined with maternal and pregnancy characteristics provides an effective screening for GDM at 11-14 weeks.

Osteocalcin, under-carboxylated osteocalcin and osteopontin are not associated with gestational diabetes mellitus but are inversely associated with leptin in non-diabetic women

OBJECTIVE

To measure serum osteocalcin (OC), under-carboxylated osteocalcin (ucOC), osteopontin (OPN), and leptin in pregnant women with gestational diabetes mellitus (GDM) and in healthy pregnant women during pregnancy and after birth and relate these markers to glucose metabolism.

METHODS

This was a prospective study including 60 women with GDM and 60 subjects with normal gestation who were evaluated at gestational week 30 and 6 weeks postpartum. Serum OC, ucOC, OPN, leptin, insulin and insulin resistance were evaluated during the study.

RESULTS

Bone biomarkers and leptin were similar between GDM and normal pregnancy. After delivery, OC, ucOC and OPN increased in both groups, while leptin decreased only in healthy controls. Bone markers did not correlate with insulin and insulin resistance in the two groups, but leptin was positively correlated with insulin and insulin resistance and negatively correlated with bone biomarkers only in healthy women. Furthermore, the women who developed diabetes postpartum had lower levels of OC than women with normal glucose tolerance.

CONCLUSION

GDM is not associated with OC, ucOC, OPN, and leptin and does not correlate with insulin resistance. At postpartum, women who develop diabetes have lower osteocalcin concentrations. Leptin correlates with insulin resistance and bone biomarkers in non-diabetic women.

Osteocalcin is higher across pregnancy in Caucasian women with gestational diabetes mellitus

OBJECTIVE

The purpose of this study was to investigate circulating concentrations of osteocalcin, a bone-derived protein, while accounting for 25-hydroxyvitamin D (25(OH)D) throughout pregnancy, and whether early gestation concentrations and changes in osteocalcin predict the subsequent diagnosis of gestational diabetes mellitus (GDM).

METHODS

This was a nested case-control study involving 48 GDM and 48 control pregnant Caucasian women (matched for age, season of conception, pre-pregnancy body mass index and pregnancy length). Maternal serum osteocalcin was measured by enzyme-linked immunosorbent assay and 25(OH)D by chemiluminescence throughout pregnancy (11-13 weeks, 24-28 weeks and predelivery). Differences between groups were compared by mixed model analysis of variance. Predictors of diagnosis of GDM were explored using generalized estimating equation models. Neonatal general health outcomes were also compared between groups.

RESULTS

Serum osteocalcin was higher across pregnancy (p=0.006) in women with GDM vs. controls, whereas serum 25(OH)D was not different (p=0.80). Both biomarkers increased with time across pregnancy (p<0.0001). However, serum osteocalcin during early pregnancy and changes in its concentration from early to mid gestation did not predict the development of GDM. There were no significant differences in anthropometry and APGAR (appearance, pulse, grimace, activity, respiration) scores in neonates of controls and cases.

CONCLUSIONS

Serum osteocalcin is elevated in Caucasian women with GDM throughout pregnancy, but was not predictive of the onset of GDM. Larger trials evaluating the role of osteocalcin and the development of GDM appear warranted.

In vivo analysis of the contribution of bone resorption to the control of glucose metabolism in mice

Osteocalcin is a hormone produced in bones by osteoblasts and regulating energy metabolism. While osteocalcin exists in two forms, γ-carboxylated and undercarboxylated only the latter appears to function as a hormone in vivo. It has been proposed recently that osteoclasts, the bone-resorbing cells, are responsible of decarboxylating, i.e. activating osteocalcin. To address the role of osteoclasts in the maintenance of energy metabolism we analyzed mutant mouse strains harboring either an increase or a decrease in osteoclasts number. Osteoprotegerin-deficient mice that are characterized by an increase in the number of osteoclasts demonstrate an increase in serum levels of undercarboxylated osteocalcin and are significantly more glucose tolerant than WT animals. Conversely, osteoclasts ablation in mice results in a decrease in serum undercarboxylated osteocalcin levels and in reduced glucose tolerance. These results support the notion that osteoclasts are controlling glucose metabolism at least in part through the regulation of osteocalcin decarboxylation.