Association of osteocalcin with obesity, insulin resistance, and cardiovascular risk factors in young adults

Osteocalcin in Infancy and Early Childhood and Its Correlation With Later Growth and Body Composition: A Longitudinal Birth Cohort Study

BACKGROUND

Osteocalcin is a metabolic active hormone, which correlates positively with bone formation and inversely with body mass index and waist circumference in adults.

OBJECTIVES

To investigate whether osteocalcin in infancy and early childhood were related to childhood growth or body composition.

METHODS

A Swedish longitudinal birth cohort with blood samples from 551 children from birth until 5 years of age. Regular anthropometric measurements were carried out up to 8 years of age and dual-energy X-ray absorptiometry (DXA) scans were also performed at 8 years. The results included p-values and Spearman's rho (ρ).

RESULTS

Osteocalcin at 4 months of age correlated inversely and consecutively with weight from 4 to 24 months and to waist circumference from 6 to 24 months in boys. The correlations for girls were limited to weight at 4 months and waist circumference at 6 and 18 months (ρ < 0.3, p = 0.001 to 0.048). The boys' osteocalcin levels at 5 years correlated positively with their height and weight at 5 and 6.5 years (ρ < 0.3, p < 0.01). Meanwhile, the girls' osteocalcin at 3 years showed positive correlations to all weight and height measurements until 8 years of age (ρ < 0.3, p = 0.003 to 0.023). DXA data showed that the boys' osteocalcin at 5 years correlated with the fat-free mass index (FFMI) (ρ 0.212, p = 0.026) but not the fat mass index (FMI) at 8 years. The opposite was seen for the girls' osteocalcin at 3 years, which correlated with FMI (ρ 0.222, p = 0.020) but not FFMI.

CONCLUSION

Early levels of osteocalcin showed inverse correlations with later weight, height and body composition in infancy and positive correlations during childhood. The weak but consistent correlations suggest that osteocalcin carries information about future growth. Girls with high osteocalcin at 3 and 5 years had a larger fat mass at 8 years, while boys, in contrast, had a larger lean mass. These sex differences need to be further explored.

The bone-heart axis in the pathogenesis of cardiovascular diseases: A narrative review

Cardiovascular diseases (CVDs) cause about 30% of deaths worldwide, increasing social and economic burden in our societies. Although the treatment of the canonical cardiovascular risk factors has reduced the impact of CVDs on morbidity and mortality in the past few years, they continue to represent a major health problem. The definition of the biological properties of the bone-heart axis has led to new insights in the pathogenesis of CVDs; hence, the aim of this review is to try to elucidate the role of this axis on the susceptibility to CVDs. There is evidence that the bone interacts with extra-skeletal organs, including the cardiovascular system, through its endocrine functions. Clinical and experimental data strongly indicate that the interplay between the bone and the cardiovascular system represents a future tool for the prevention, diagnosis and treatment of CVDs. The identification of these non-canonical cardiovascular risk factors could prompt pharmacological research towards new target therapy aimed at precision medicine.

Carboxylated Osteocalcin as an Independent Predictor of Mean Arterial Pressure and the Atherogenic Index in Adults

Bone-derived proteins, including carboxylated osteocalcin (cOC), are thought to play a role in cardiovascular and metabolic health. cOC is recognized for its strong affinity for calcium hydroxyapatite and its possible involvement in vascular calcification and lipid metabolism. Although the undercarboxylated form of osteocalcin (ucOC) has been widely researched, the connections between cOC and cardiovascular risk markers, such as mean arterial pressure (MAP), pulse pressure (PP), and the atherogenic index, are still not well understood. This cross-sectional study comprised 81 adults from Western Mexico; selection was based on rigorous inclusion criteria. Participants underwent various measurements, including anthropometric, biochemical, and cardiovascular assessments, such as the body mass index (BMI), body fat percentage, serum glucose, insulin resistance (HOMA-IR), glycated hemoglobin (HbA1c), lipid profile, creatinine, blood pressure parameters, and the atherogenic index. Serum cOC levels were determined using an enzyme-linked immunosorbent assay (ELISA). The study examined the relationships between cOC and cardiovascular/metabolic markers using inferential statistics and correlation coefficients. Multivariate linear analysis was performed to identify factors independently associated with the serum levels of cOC. Multivariate analysis revealed that MAP (B coefficient: 0.138, 95% CI: 0.028-0.247, p = 0.015) and the atherogenic index (B coefficient: 0.599, 95% CI: -0.039-1.161, p = 0.037) are independent predictors of cOC levels. A positive correlation was observed between cOC, PP, the atherogenic index, and HbA1, as well as an inverse correlation between cOC and HDL-c among the participants. Additionally, PP was positively correlated with HOMA-IR. Participants with elevated cOC levels showed higher MAP and atherogenic index values, indicating a potential connection between cOC and cardiovascular risk. cOC is independently associated with MAP and the atherogenic index, suggesting it may play a role in vascular remodeling and lipid metabolism. These results emphasize the importance of the bone-vascular axis in cardiovascular health and indicate that cOC might be a useful biomarker for assessing cardiovascular risk. Additional research is necessary to confirm these findings in larger, long-term studies and to investigate the mechanisms that connect cOC with cardiovascular outcomes.

A trend of osteocalcin in diabetes mellitus research: bibliometric and visualization analysis

Background

Osteocalcin has attracted attention for its potential role in diabetes management. However, there has been no bibliometric assessment of scientific progress in this field.

Methods

We analysed 1680 articles retrieved from the Web of Science Core Collection (WoSCC) between 1 January 1986 and 10 May 2024 using various online tools.

Result

These papers accumulated 42,714 citations,with an average of 25.43 citations per paper. Publication output increased sharply from 1991 onwards. The United States and China are at the forefront of this research area.

Discussion

The keywords were grouped into four clusters: 'Differential and functional osteocalcin genes', 'Differential expression of osteocalcin genes in relation to diabetes mellitus', 'Role of osteocalcin in the assessment of osteoporosis and diabetes mellitus', and 'Indirect involvement of osteocalcin in metabolic processes'. Analysis using the VoS viewer suggests a shift in research focus towards the correlation between osteocalcin levels and diabetic complications, the clinical efficacy of therapeutic agents or vitamins in the treatment of osteoporosis in diabetic patients, and the mechanisms by which osteocalcin modulates insulin action. The proposed focus areas are "osteocalcin genes", "insulin regulation and osteoporosis ", "different populations", "diabetes-related complications" and "type 2 diabetes mellitus","effect of osteocalcin expression on insulin sensitivity as well as secretion","osteocalcin expression in different populations of diabetic patients and treatment-related studies".

Reference limits for osteocalcin in infancy and early childhood: A longitudinal birth cohort study

OBJECTIVE

The longitudinal variations in serum levels of the hormone osteocalcin is largely unknown during infancy and early childhood. Our aim was to establish reference limits for total serum osteocalcin during specific time points from birth until 5 years of age and present those in the context of sex, breastfeeding practices and gestational age (GA).

DESIGN

Blood samples from 551 Swedish children were analysed at birth, 4, 12, 36 and 60 months of age. Total serum osteocalcin was measured using the IDS-iSYS N-MID Osteocalcin assay technique. Information about the mother, birth, anthropometrics and a food diary were collected.

RESULTS

Sex-specific and age-specific reference limits were established for the five time points. The median osteocalcin levels over time were 40.8, 90.0, 67.8, 62.2 and 80.9 μg/L for boys and 38.1, 95.5, 78.3, 73.9 and 92.6 μg/L for girls. Lower GA was associated to higher osteocalcin at birth, and ongoing breastfeeding was associated to higher osteocalcin levels.

CONCLUSION

Osteocalcin followed a wavelike pattern with low levels in the umbilical cord and a postnatal peak during the first year which then declined and rose again by the age of five. Knowledge of this wavelike pattern and association to factors as sex, breastfeeding and GA may help clinicians to interpret individual osteocalcin levels and guide in future research.

Preptin: A New Bone Metabolic Parameter?

Preptin is a 34-aminoacid peptide derived from the E-peptide of pro-insulin-like growth factor 2 (pro-IGF2) that is co-secreted with insulin and upregulates glucose-mediated insulin secretion. High serum preptin levels were described in conditions associated with insulin resistance, such as polycystic ovary syndrome and type 2 diabetes mellitus (T2M). Insulin and also IGF2 are known to be anabolic bone hormones. The "sweet bone" in T2M usually associates increased density, but altered microarchitecture. Therefore, preptin was proposed to be one of the energy regulatory hormones that positively impacts bone health. Experimental data demonstrate a beneficial impact of preptin upon the osteoblasts. Preptin also appears to regulate osteocalcin secretion, which in turn regulates insulin sensitivity. Preptin is greatly influenced by the glucose tolerance status and the level of physical exercise, both influencing the bone mass. Clinical studies describe low serum preptin concentrations in osteoporosis in both men and women, therefore opening the way towards considering preptin a potential bone anabolic therapy. The current review addresses the relationship between preptin and bone mass and metabolism in the experimental and clinical setting, also considering the effects of preptin on carbohydrate metabolism and the pancreatic-bone loop.

Circulating Extracellular Vesicles Impair Mesenchymal Stromal Cell Differentiation Favoring Adipogenic Rather than Osteogenic Differentiation in Adolescents with Obesity

Excess body weight has been considered beneficial to bone health because of its anabolic effect on bone formation; however, this results in a poor quality bone structure. In this context, we evaluated the involvement of circulating extracellular vesicles in the impairment of the bone phenotype associated with obesity. Circulating extracellular vesicles were collected from the plasma of participants with normal weight, as well as overweight and obese participants, quantified by flow cytometry analysis and used to treat mesenchymal stromal cells and osteoblasts to assess their effect on cell differentiation and activity. Children with obesity had the highest amount of circulating extracellular vesicles compared to controls. The treatment of mesenchymal stromal cells with extracellular vesicles from obese participants led to an adipogenic differentiation in comparison to vesicles from controls. Mature osteoblasts treated with extracellular vesicles from obese participants showed a reduction in differentiation markers in comparison to controls. Children with obesity who regularly performed physical exercise had a lower circulating extracellular vesicle amount in comparison to those with a sedentary lifestyle. This pilot study demonstrates how the high amount of circulating extracellular vesicles in children with obesity affects the bone phenotype and that physical activity can partially rescue this phenotype.

Association between osteocalcin, a pivotal marker of bone metabolism, and secretory function of islet beta cells and alpha cells in Chinese patients with type 2 diabetes mellitus: an observational study

BACKGROUND

Several recent studies have found that Osteocalcin (OCN), a multifunctional protein secreted exclusively by osteoblasts, is beneficial to glucose metabolism and type 2 diabetes mellitus (T2DM). However, the effects of OCN on islets function especially islet ɑ cells function in patients with type 2 diabetes mellitus characterized by a bi-hormonal disease are still unclear. The purpose of this cross-sectional study was to investigate the relationship between serum OCN and the secretion of islet β cells and ɑ cells in Chinese patients with type 2 diabetes mellitus.

METHODS

204 patients with T2DM were enrolled. Blood glucose (FBG, PBG0.5h, PBG1h, PBG2h, PBG3h), insulin (FINS, INS0.5h, INS1h, INS2h, INS3h), C-peptide (FCP, CP0.5h, CP1h, CP2h, CP3h), and glucagon (GLA0, GLA0.5 h, GLA1h, GLA2h, GLA3h) levels were measured on 0 h, 0.5 h, 1 h, 2 h, and 3 h after a 100 g standard bread meal load. Early postprandial secretion function of islet β cells was calculated as Δcp0.5h = CP0.5-FCP. The patients were divided into low, medium and high groups (T1, T2 and T3) according to tertiles of OCN. Comparison of parameters among three groups was studied. Correlation analysis confirmed the relationship between OCN and pancreatic secretion. Multiple regression analysis showed independent contributors to pancreatic secretion.

MAIN RESULTS

FBG, and PBG2h were the lowest while Δcp0.5h was the highest in the highest tertile group (respectively, p < 0.05). INS3h, area under the curve of insulin (AUCins3h) in T3 Group were significantly lower than T1 Group (respectively, p < 0.05). GLA1h in T3 group was lower than T1 group (p < 0.05), and GLA0.5 h in T3 group was lower than T2 and T1 groups (p < 0.05). Correlation analysis showed OCN was inversely correlated with Homeostatic model of insulin resistance (HOMA-IR), INS3h, AUCins3h (p < 0.05), and was still inversely correlated with FCP, GLA0.5 h, GLA1h, area under the curve of glucagon (AUCgla3h) (respectively, p < 0.05) after adjustment for body mass index (BMI) and alanine aminotransferase (ALT). The multiple regression analysis showed that OCN was independent contributor to Δcp0.5h, GLA0.5h and GLA1h (respectively, p < 0.05).

CONCLUSIONS

Higher serum OCN level is closely related to better blood glucose control, higher insulin sensitivity, increased early-phase insulin secretion of islet β cells and appropriate inhibition of postprandial glucagon secretion of islet ɑ cells in adult patients with type 2 diabetes mellitus.

The Effect of Levothyroxine in Comparison with Placebo on Serum Osteocalcin Levels in Patients with Subclinical Hypothyroidism

BACKGROUND AND OBJECTIVE

Subclinical hypothyroidism can potentially develop into overt hypothyroidism. Thyroid hormones have substantial roles in metabolism and glucose homeostasis and thus, are closely related to determinant factors of metabolic syndromes, such as obesity and insulin resistance. Osteocalcin is considered a predictor of metabolic conditions in thyroid diseases. This study aimed to investigate the effect of levothyroxine vs. placebo on serum osteocalcin levels in patients with subclinical hypothyroidism.

METHODS

This randomized clinical trial was performed on 30 patients with subclinical hypothyroidism, who were referred to the endocrine clinics of Ghaem and Imam Reza hospitals in Mashhad, Iran. After giving informed consent, patients were randomly divided into intervention (50 μg/- day levothyroxine for 2 months) and control (placebo) groups. Serum levels of osteocalcin, thyroid hormones, lipid profile, insulin, and fasting glucose, as well as other clinical and anthropometric data, were measured at baseline and at the end of the study. SPSS was used to analyze the data, and p < 0.05 was considered significant.

RESULTS

Mean age in the intervention and control groups was 35.07 ± 9.94 and 31.30 ± 4.30, respectively (p = 0.20). There was no significant difference between osteocalcin levels before and after the intervention in either of the groups (p = 0.54). TSH level was significantly decreased in the levothyroxine group after the intervention (p < 0.01). T4 level was significantly increased in the intervention group (p = 0.02).

CONCLUSION

Levothyroxine had no significant effect on the increasing levels of serum osteocalcin in patients with subclinical hypothyroidism.

The inverse association of body adiposity index and bone health in the older adults: A report from a developing country

The ageing process influences body composition and could be related to bone health. The current study was set out to evaluate the association between body adiposity index (BAI) and bone health in older adults. This is a cross-sectional study performed on 178 elderly persons (51 men and 127 women) with a mean age of 67.04 (range: 60-83) who was referred to the determined 25 health centres in Tehran. The anthropometric measurements were done. Further, serum 25-hydroxy vitamin D (25(OH)D), parathormone (PTH), high-sensitivity C-reactive protein (hs-CRP), osteocalcin and urine C-terminal telopeptide I (CTX-I) were collected. The mean of body mass index (P < .001), body weight (P = .002), body fat (P < .001), waist circumference (P < .001), hip circumference (P < .001), urine CTX-I concentration (P = .011), 25(OH)D (P = .030), was higher in the highest BAI category in comparison with the lowest one. BAI was negatively correlated with urine CTX-I concentration (r=-0.165, P = .028). Moreover, linear regression showed an inverse association between BAI with urine CTX-I (β = -0.165, P = .025) and 25(OH)D (β = -0.039, P = .029). Moreover, the percentage of body fat was positively associated with serum hs-CRP (β = 0.026, P = .002). Our study showed a significant inverse association between BAI with urinary CTX-I which shows the effect of obesity on bone health. This study suggests that more clinical and prospective studies for monitoring body fat may have some favourable impacts on bone health.

Osteocalcin Is Independently Associated with C-Reactive Protein during Lifestyle-Induced Weight Loss in Metabolic Syndrome

Bone-derived osteocalcin has been suggested to be a metabolic regulator. To scrutinize the relation between osteocalcin and peripheral insulin sensitivity, we analyzed changes in serum osteocalcin relative to changes in insulin sensitivity, low-grade inflammation, and bone mineral density following lifestyle-induced weight loss in individuals with metabolic syndrome (MetS). Participants with MetS were randomized to a weight loss program or to a control group. Before and after the 6-month intervention period, clinical and laboratory parameters and serum osteocalcin levels were determined. Changes in body composition were analyzed by dual-energy X-ray absorptiometry (DXA). In participants of the intervention group, weight loss resulted in improved insulin sensitivity and amelioration of inflammation. Increased serum levels of osteocalcin correlated inversely with BMI (r = −0.63; p< 0.001), total fat mass (r = −0.58, p < 0.001), total lean mass (r = −0.45, p < 0.001), C-reactive protein (CRP) (r = −0.37; p < 0.01), insulin (r = −0.4; p < 0.001), leptin (r = −0.53; p < 0.001), triglycerides (r = −0.42; p < 0.001), and alanine aminotransferase (ALAT) (r = −0.52; p < 0.001). Regression analysis revealed that osteocalcin was independently associated with changes in CRP but not with changes in insulin concentration, fat mass, or bone mineral density, suggesting that weight loss-induced higher serum osteocalcin is primarily associated with reduced inflammation.

Association between Circulating Osteocalcin and Cardiometabolic Risk Factors following a 4-Week Leafy Green Vitamin K-Rich Diet

<b><i>Background:</i></b> Evidence suggests that lower serum undercarboxylated osteocalcin (ucOC) may be negatively associated with cardiometabolic health. We investigated whether individuals with a suppression of ucOC following an increase in dietary vitamin K1 exhibit a relative worsening of cardiometabolic risk factors. <b><i>Materials and Methods:</i></b> Men (<i>n</i> = 20) and women (<i>n</i> = 10) aged 62 ± 10 years participated in a randomized, controlled, crossover study. The primary analysis involved using data obtained from participants following a high vitamin K1 diet (HK; 4-week intervention of increased leafy green vegetable intake). High and low responders were defined based on the median percent reduction (30%) in ucOC following the HK diet. Blood pressure (resting and 24 h), arterial stiffness, plasma glucose, lipid concentrations, and serum OC forms were assessed. <b><i>Results:</i></b> Following the HK diet, ucOC and ucOC/tOC were suppressed more (<i>p</i> &#x3c; 0.01) in high responders (41 and 29%) versus low responders (12 and 10%). The reduction in ucOC and ucOC/tOC was not associated with changes in blood pressure, arterial stiffness, plasma glucose, or lipid concentrations in the high responders (<i>p</i> &#x3e; 0.05). <b><i>Discussion/Conclusion:</i></b> Suppression of ucOC via consumption of leafy green vegetables has no negative effects on cardiometabolic health, perhaps, in part, because of cross-talk mechanisms.

Increased Plasma Osteocalcin, Oral Disease, and Altered Mandibular Bone Density in Postmenopausal Women

An association between oral diseases and postmenopausal status has been recognized. However, the relationship between all oral disease, mandibular bone density, health status, and osteocalcin (OCN) bone markers in postmenopausal dental patients has not been reported. This study was therefore to verify the differences in plasma OCN levels, dental, periodontal, and oral mucosal disease, and mandibular bone density alterations from panoramic radiograph and systemic parameters in postmenopausal women, compared to premenopausal women. Oral, radiographic, and blood examination were performed in 92 females. Dental, periodontal, and oral mucosal statuses were recorded. Health profile parameters were collected from medical charts. Plasma OCN was evaluated by enzyme-linked immunosorbent assay. Forty-two (45.7%) participants were postmenopausal with a higher median age (55 (51, 62) years) than the premenopausal group (43 (38, 45) years). Overweight or obesity, hypercholesterolemia, and impaired fasting blood sugar were more prevalent in postmenopause. The average postmenopausal OCN level (425.62 ng/mL) was significantly higher than the premenopausal group (234.77 ng/mL, p < 0.001). The average number of missing teeth, mean attachment loss, alveolar bone loss, periapical lesion count, and clinical oral dryness score were also significantly higher in postmenopause (p=0.008,   < 0.001,  0.031,  0.006,  and 0.005, respectively). However, mandibular bone density determined by mandibular cortical index was lower in postmenopause (p < 0.001). The panoramic mandibular index, mandibular cortical width, fractal dimension, and other oral mucosal disease did not differ between the groups. Postmenopause was associated with elevated plasma OCN (β = 0.504, p < 0.001) when related covariates were adjusted. Elevated plasma OCN, oral mucosal dryness, high number of periapical radiolucencies and missing teeth, and lower mandibular bone density from panoramic radiograph were prevalent in postmenopausal women. Dentists should suspect an increased risk of low bone mineral density in postmenopausal patients who display these clinical and radiographic findings, and they should be referred for further examination. Plasma OCN may interconnect a relationship between postmenopausal status and the low mandibular bone density.

Association of Serum Total Osteocalcin Concentrations With Endogenous Glucocorticoids and Insulin Sensitivity Markers in 12-Year-Old Children: A Cross-Sectional Study

Background: Osteocalcin (OC) is an osteoblast-derived marker of bone turnover that has recently been linked to glucose metabolism, glucocorticoid action, and cardiovascular risk. Objective: We determined whether serum total OC (tOC) is associated with cardiometabolic factors, such as insulin sensitivity (IS) markers and endogenous glucocorticoids in 12-year-old children. In addition, we assessed whether low birth weight or exposure to maternal preeclampsia affect tOC concentrations. Methods: In this cross-sectional study, 192 children (109 girls) were studied at 12 years of age. Seventy of them had been born small (SGA), 78 appropriate for gestational age (AGA), and 44 from preeclamptic pregnancies (PRE) as AGA. Blood pressure was measured, and fasting blood samples were collected for markers of glucose metabolism, osteoblast, adipocyte, and adrenocortical function. IS was estimated by Quantitative Insulin Sensitivity Check Index (QUICKI). Free cortisol index (FCI) was calculated as serum cortisol/corticosteroid binding globulin. Results: The highest tOC concentrations were detected in midpubertal children (Tanner B/G stage 3). The children in the highest tOC quartile (n = 48) had lower body mass index (BMI), waist-to-height ratio, diastolic blood pressure, leptin, cortisol/cortisone ratio and FCI, and higher insulin-like growth factor I (IGF-I), IGF-binding protein-1 (IGFBP-1), IGFBP-3, and alkaline phosphatase (ALP) than those in the lower tOC quartiles (p < 0.02 for all). QUICKI was similar in these subgroups. In logistic regression analysis, pubertal developmental stages 2 and 3, high ALP, IGF-I, and low FCI and BMI (p < 0.02 for all) were associated independently with higher tOC. The means of serum tOC and IS markers were similar in the SGA, AGA, and PRE subgroups. Conclusions: In both sexes, the highest tOC levels were detected in midpubertal children reflecting the fast pubertal growth phase. Higher tOC levels were associated with lower BMI and FCI, whereas no association was found with IS. Birth weight or exposure to preeclampsia had no effect on tOC concentrations.

V, Kulkarni S, Diwekar-Joshi M, Watve M. Inferring causal pathways among three or more variables from steady-state correlations in a homeostatic system

Cross-sectional correlations between two variables have limited implications for causality. We examine here whether it is possible to make causal inferences from steady-state data in a homeostatic system with three or more inter-correlated variables. Every putative pathway between three variables makes a set of differential predictions that can be tested with steady state data. For example, among 3 variables, A, B and C, the coefficient of determination, rAC2 is predicted by the product of rAB2 and rBC2 for some pathways, but not for others. Residuals from a regression line are independent of residuals from another regression for some pathways, but positively or negatively correlated for certain other pathways. Different pathways therefore have different prediction signatures, which can be used to accept or reject plausible pathways using appropriate null hypotheses. The type 2 error reduces with sample size but the nature of this relationship is different for different predictions. We apply these principles to test the classical pathway leading to a hyperinsulinemic normoglycemic insulin-resistant, or pre-diabetic, state using four different sets of epidemiological data. Currently, a set of indices called HOMA-IR and HOMA-β are used to represent insulin resistance and glucose-stimulated insulin response by β cells respectively. Our analysis shows that if we assume the HOMA indices to be faithful indicators, the classical pathway must in turn be rejected. In effect, among the populations sampled, the classical pathway and faithfulness of the HOMA indices cannot be simultaneously true. The principles and example shows that it is possible to infer causal pathways from cross sectional correlational data on three or more correlated variables.

Waist circumference is an effect modifier of the association between bone mineral density and glucose metabolism

OBJECTIVE

The role of bone markers on insulin resistance (IR) remains controversial. The objective of this study is to evaluate the association between bone mineral density (BMD) and glucose metabolism and investigate if visceral hyperadiposity, evaluated by waist circumference (WC), is an effect modifier of this association.

SUBJECTS AND METHODS

Cross-sectional analysis with 468 young adults from the fourth follow-up of the 1978/79 Ribeirão Preto prospective birth cohort, Brazil. BMD, total osteocalcin (OC), fasting plasma glucose and insulin concentrations were assessed. IR, sensitivity (S) and secretion (β) were estimated by homeostasis model assessment (HOMA) indexes. Multiple linear regression models were constructed to estimate the association between BMD and glucose metabolism. Beta coefficient, R2 and p-values were provided. WC was tested as an effect modifier and OC as a confounder. The covariates were selected based on Direct Acyclic Graph.

RESULTS

Significant interaction between BMD (femoral neck and proximal femur areas) and WC on glucose metabolism was observed in the adjusted models. Subjects with increased WC presented a positive association between BMD and log HOMA1-IR while an inverse association was found in those with normal WC (femoral neck R2 = 0.17, p = 0.036; proximal femur R2 = 0.16, p = 0.086). BMD was negatively associated with log HOMA2-S in individuals with increased WC and positively in those with normal WC (femoral neck R2 = 0.16, p = 0.042; proximal femur R2 = 0.15, p = 0.097). No significant associations between BMD, log HOMA2-β and OC and glucose metabolism markers were observed.

CONCLUSIONS

BMD was associated with glucose metabolism, independently of OC, and WC modifies this association.

Longitudinal changes in bone-testis axis and their associations with insulin resistance in 11- to 12-year-old boys

PURPOSE

Associations between osteocalcin (OCN), an osteoblast-specific hormone, and different markers of energy metabolism and insulin resistance have been reported in adults, but few studies have investigated this in children. The aim of the current study was to investigate serum OCN levels during pubertal development in normal weight (NW) and overweight (OW) boys, and to evaluate possible associations of OCN with body composition, testosterone, insulin resistance and adipocytokine values during puberty.

METHODS

Ninety 11- to 12-year-old boys were investigated at 12-month intervals over the next 2years. Boys were divided by their BMI into NW (n=60) and OW (n=30) groups. Serum OCN, testosterone, leptin, adiponectin, insulin, HOMA-IR score, and body composition were measured.

RESULTS

Pubertal development over the 2-year period was similar in both groups. Serum OCN was not different at the beginning of the study and increased similarly in both groups. However, at the end of the study, NW had higher OCN than OW (142.9±5.2 vs. 124.0±7.4ng/ml; p<0.05). OW had higher leptin, insulin and HOMA-IR compared to NW, and these differences remained significant through the 2-year period. Testosterone, insulin and HOMA-IR increased through the study period in both groups. In multiple regression analyses increment in OCN was associated with the increase in testosterone in NW (p<0.001) and OW (p=0.049) boys. Increment in OCN was also associated with the increase in insulin (p=0.019) and HOMA-IR (p=0.012) over the 2-year period in NW boys.

CONCLUSION

Serum OCN concentration increases in puberty and the increment is positively associated with the rise in testosterone level in both NW and OW boys. The positive association between the rise in OCN and insulin in NW boys would suggest that OCN may have a role in the development of insulin resistance.

Association between serum osteocalcin and body mass index: a systematic review and meta-analysis

PURPOSE

Osteocalcin is considered as a bone-derived hormone affecting on the body fat distribution and body mass index. Several cross-sectional studies have investigated the association between serum osteocalcin and body mass index. The aim of this study was to summarize the evidence on the relationship between serum osteocalcin and body mass index.

METHODS

We conducted a complete search up to November 2016 in PubMed and SCOPUS and reviewed reference list of all relevant articles and reviews. The DerSimonian-Laird method were used to pool effect sizes of eligible studies. The potential sources of heterogeneity were assessed using the standard χ 2 test.To find possible the sources of between-study heterogeneity, we carried out subgroup analyses based on sex, and type of study population.

RESULTS

There was a significant inverse association in the overall result of this study between serum osteocalcin levels and BMI(r = -0.161; 95% CI: -0.197, -0.124, p < 0.000). In the subgroup analysis to find the sources of significant heterogeneity between-study, we observed that the type of the study population may be the source of between-study heterogeneity and the most correlation was seen in metabolic syndrome studies (r = -0.265; p = 0.000).

CONCLUSION

Findings from the available data indicated an overall significant inverse association between serum osteocalcin and body mass index. Further studies based on the type of study population are needed to better clarify these associations.

Serum levels of undercarboxylated osteocalcin are related to cardiovascular risk factors in patients with type 2 diabetes mellitus and healthy subjects

AIM

To determine a potential relationship between serum undercarboxylated (ucOC) concentration and cardiovascular risk factors in type 2 diabetes (T2D) patients and healthy subjects (HS).

METHODS

A cross-sectional study was conducted on 140 subjects classified into two groups, 70 with T2D and 70 HS. Medical history and physical examination with anthropometric measurements were obtained from all subjects. Body fat percentage was determined by bioelectrical impendency analysis. Serum ucOC concentration was determined by enzyme immunoassay, while serum levels of insulin and hsCRP were obtained using high sensitivity enzyme-linked immunosorbent assay. Insulin resistance was determined using the homeostasis model assessment-IR. Lipid profile [triglycerides, total cholesterol (TC), high-density lipoproteins (HDL-c), low density lipoproteins (LDL-c), very low-density lipoproteins] was determined by spectrophotometry and standard formulas when applicable.

RESULTS

The T2D patient group showed significantly higher values of waist circumference, waist-to-hip ratio, systolic blood pressure (SBP), diastolic blood pressure (DBP), current smoking, and alcohol use when compared to the HS group (P < 0.05). We observed a significantly lower serum ucOC concentration in T2D than in HS (1.5 ± 1.4 vs 2.3 ± 1.8, P < 0.05). In the whole study population, ucOC concentration was inversely correlated with body mass index (BMI) (r = -0.236, P < 0.05), fasting plasma glucose (r = -0.283, P < 0.01) and HDL-c (r = -0.255, P < 0.05); and positively correlated with LDL-c/HDL-c ratio (r = 0.306, P < 0.05) and TC/HDL-c ratio (r = 0.284, P < 0.05). In the T2D group, serum ucOC concentration was inversely correlated with BMI (r = -0.310, P < 0.05) and body-fat percentage (r = -0.311, P < 0.05), and positively correlated with DBP (r = 0.450, P < 0.01). In HS group a positive correlation between serum levels of ucOC and SBP (r = 0.277, P < 0.05) was observed.

CONCLUSION

Serum ucOC is a potential marker for cardiovascular risk in Mexicans because it is related to adiposity parameters, blood pressure and lipid profile.

Serum osteocalcin levels are inversely associated with the presence of nonalcoholic fatty liver disease in patients with coronary artery disease

Osteocalcin plays roles in energy, glucose, and lipid metabolism. Consequently, the relationship between osteocalcin level and nonalcoholic fatty liver disease (NAFLD) is of interest. The present study explored the possible correlation between serum osteocalcin levels and NAFLD in patients with CAD. The study enrolled 174 inpatients diagnosed with CAD by coronary angiography (CAG). The presence of fatty liver disease was confirmed by abdominal ultrasonography. NAFLD was diagnosed using the working definition of the revised guidelines for the management of NAFLD published by the Chinese Liver Disease Association. Serum osteocalcin levels were determined using electrochemiluminescent immunoassays. Patients with NAFLD had lower serum osteocalcin levels than those without NAFLD [16.2 (14.2-23.8) vs. 20.7 (15.6-26.2) ng/mL, P<0.05]. After adjustment for gender and age, serum osteocalcin levels correlated with the presence of NAFLD (r=-0.260, P=0.010), fasting plasma glucose level (r=-0.230, P=0.023) and glycated hemoglobin A1c level (r=-0.229, P=0.023). Osteocalcin was an independent factor for the presence of NAFLD (β=-0.097, P=0.025). These data suggested that serum osteocalcin levels were negatively associated with the presence of NAFLD in patients with CAD.

Undercarboxylated osteocalcin as a biomarker of subclinical atherosclerosis in non-dialysis patients with chronic kidney disease

BACKGROUND

Studies in recent years have shown that undercarboxylated osteocalcin (uOC) not only maintains bone mineralization, but is also involved in the regulation of atherosclerosis. However, a correlation between uOC and carotid atherosclerosis in non-dialysis patients with chronic kidney disease (CKD) has not been investigated. A total of 240 non-dialysis patients with CKD were included in the study. For these patients, the median estimated glomerular filtration rate (eGFR) was 20.05 (12.43-49.32) ml/min/1.73m(2). Serum uOC levels were measured using enzyme-linked immunosorbent assay (ELISA). Carotid ultrasonography was performed to assess carotid atherosclerotic plaques and intima-media thickness (IMT) in an attempt to analyze the relationship between uOC level and carotid atherosclerosis.

RESULTS

The uOC levels of non-dialysis patients with CKD were significantly lower than those of healthy controls [28.16 (21.40-45.85) ng/mL vs. 36.42 (28.05-49.28) ng/mL, P < 0.01]. The uOC levels gradually decreased as CKD progressed (P < 0.01). The uOC levels were significantly lower in patients with carotid plaques than in patients without carotid plaques [25.98 (20.14-31.35) ng/mL vs. 31.02 (25.86-36.40) ng/mL, P < 0.01]. uOC level showed significant negative correlation with IMT (r = -0.33, P < 0.01). Logistic regression analysis revealed that after adjustment for various confounding factors, decreased uOC levels were shown to indicate increased possibility of carotid atherosclerotic plaque development in non-dialysis patients with CKD (on every 1 SD decrease in the uOC level, odds ratio 1.70, 95 % confidence interval 1.24-2.98, P < 0.01). Multivariate stepwise regression analysis demonstrated that decreased uOC level (β = -0.163, P < 0.05) was an independent risk factor for increased carotid IMT in non-dialysis patients with CKD.

CONCLUSION

Serum uOC levels in non-dialysis patients with CKD are significantly lower than those in healthy individuals, and uOC is closely associated with subclinical atherosclerosis in CKD patients.

The effects of acute hyperinsulinemia on bone metabolism

Insulin signaling in bone-forming osteoblasts stimulates bone formation and promotes the release of osteocalcin (OC) in mice. Only a few studies have assessed the direct effect of insulin on bone metabolism in humans. Here, we studied markers of bone metabolism in response to acute hyperinsulinemia in men and women. Thirty-three subjects from three separate cohorts (n=8, n=12 and n=13) participated in a euglycaemic hyperinsulinemic clamp study. Blood samples were collected before and at the end of infusions to determine the markers of bone formation (PINP, total OC, uncarboxylated form of OC (ucOC)) and resorption (CTX, TRAcP5b). During 4 h insulin infusion (40 mU/m(2) per min, low insulin), CTX level decreased by 11% (P<0.05). High insulin infusion rate (72 mU/m(2) per min) for 4 h resulted in more pronounced decrease (-32%, P<0.01) whereas shorter insulin exposure (40 mU/m(2) per min for 2 h) had no effect (P=0.61). Markers of osteoblast activity remained unchanged during 4 h insulin, but the ratio of uncarboxylated-to-total OC decreased in response to insulin (P<0.05 and P<0.01 for low and high insulin for 4 h respectively). During 2 h low insulin infusion, both total OC and ucOC decreased significantly (P<0.01 for both). In conclusion, insulin decreases bone resorption and circulating levels of total OC and ucOC. Insulin has direct effects on bone metabolism in humans and changes in the circulating levels of bone markers can be seen within a few hours after administration of insulin.

Osteocalcin and type 2 diabetes risk in Latinos: a life course approach

OBJECTIVE

To examine associations between circulating levels of the bone-derived protein osteocalcin (OC) and type 2 diabetes (T2D) risk in Latino children and adults.

METHODS

Serum OC was measured in 136 children and 531 adults who had the following T2D risk factors assessed, body mass index (BMI), Hemoglobin A1c (HbA1c), fasting and 2-hour glucose during an oral glucose tolerance test.

RESULTS

OC was significantly higher in children than adults (209.0 ± 12.1 vs. 41.0 ± 0.9 ng/ml, p<0.0001). In adults, OC was inversely associated (all p<0.001) with BMI (r=-0.2), HbA1c (r=-0.2), fasting glucose (r=-0.16), and 2-hour glucose (r=-0.21), while there were no significant associations in children. There was a stepwise decrease in OC with increasing dysglycemia in adults, normoglycemic (44.1 ± 1.3 ng/ml), prediabetic (39.3 ± 1.3 ng/ml), and T2D (31.8 ± 1.2 ng/ml), (p<0.0001), whereas there were no differences between normal and prediabetic youth (195.7 ± 16.1 vs. 194.7 ± 25.8 ng/ml, p=0.3).

CONCLUSIONS

OC was inversely associated with T2D risk in Latino adults; however, this pattern was not observed in children.

Osteocalcin is inversely associated with adiposity and leptin in adolescent boys

BACKGROUND/AIMS

Recently, osteocalcin (OC), an osteoblast-derived hormone, has been found to correlate with adiposity, adipocytokines and insulin resistance in adults, but few studies have investigated this in children. The aim of this study was to investigate these associations in adolescent boys, for whom it is a time of significant bone mineral accrual, taking into account possible confounders related to adipose and bone tissues.

PARTICIPANTS/METHODS

Participants were 141 adolescent boys (mean age 13.9±0.7 years), who were divided into tertiles according to OC levels. Across these groups, differences in total body fat mass (FM), body fat distribution, adiponectin, leptin and insulin resistance values were examined with relation to age, pubertal stage, daily energy and calcium intakes, and physical activity.

RESULTS

Mean body mass index (BMI), FM, body fat% and leptin differed significantly between subjects in the three OC tertiles after adjustment for age, pubertal stage, energy and calcium intakes, and physical activity. There were no differences in fat free mass (FFM), bone mineral content, energy and calcium intakes, physical activity, adiponectin and insulin resistance values between study groups. For the entire cohort, mean serum OC was 130.2±45.2 ng/mL and was related to body mass, BMI, FM, body fat distribution and leptin. Circulating OC was not associated with FFM, daily energy and calcium intakes, physical activity, adiponectin or insulin resistance (insulin, glucose, homeostasis model assessment-insulin resistance) values.

CONCLUSIONS

In male adolescents, OC is inversely related to body adiposity and leptin values, even after consideration of several factors that may affect bone and adipose tissues.

Childhood wrist circumference is not a predictor of insulin resistance in adulthood

We sought to determine whether childhood wrist circumference predicts insulin resistance in adulthood. Measures were taken in prepubertal children and then approximately 30 years later in the same subjects as adults. Our findings suggest that wrist circumference in childhood is not a predictor of insulin resistance in adulthood.

GGCX and VKORC1 inhibit osteocalcin endocrine functions

Cell-specific gene inactivation experiments delineate the functions of the enzymes required for osteocalcin modification and demonstrate that it is its uncarboxylated form that acts as a hormone.

Osteocalcin (OCN) is an osteoblast-derived hormone favoring glucose homeostasis, energy expenditure, male fertility, brain development, and cognition. Before being secreted by osteoblasts in the bone extracellular matrix, OCN is γ-carboxylated by the γ-carboxylase (GGCX) on three glutamic acid residues, a cellular process requiring reduction of vitamin K (VK) by a second enzyme, a reductase called VKORC1. Although circumstantial evidence suggests that γ-carboxylation may inhibit OCN endocrine functions, genetic evidence that it is the case is still lacking. Here we show using cell-specific gene inactivation models that γ-carboxylation of OCN by GGCX inhibits its endocrine function. We further show that VKORC1 is required for OCN γ-carboxylation in osteoblasts, whereas its paralogue, VKORC1L1, is dispensable for this function and cannot compensate for the absence of VKORC1 in osteoblasts. This study genetically and biochemically delineates the functions of the enzymes required for OCN modification and demonstrates that it is the uncarboxylated form of OCN that acts as a hormone.

Reduced serum total osteocalcin is associated with central obesity in Korean children

BACKGROUND

Recently, osteocalcin (OC), an osteoblast-derived hormone, has been suggested as a new link between obesity and insulin resistance in humans. However, few studies regarding the relationship between OC and obesity in Asian children have been published. We investigated the association of OC with adiposity, insulin resistance and metabolic syndrome (MetS) in Korean children.

METHODS

Two hundred and nine (100 boys, 109 girls) children (age: 9.78 ± 1.05 years, body mass index (BMI): 22.27 ± 5.34 kg/m(2)) participated in this cross-sectional study. Anthropometric parameters, insulin resistance, lipid profiles, total OC, and an inflammatory marker, C-reactive protein (CRP), were measured. MetS phenotype was also determined.

RESULTS

Serum total OC levels were significantly lower in overweight or obese children (76.96 ± 27.08 ng/ml vs. 66.91 ± 21.39 ng/ml, p = 0.020) and it was negatively associated with body fat after controlling for age, gender and BMI. Serum total OC concentrations were significantly lower in participants with central obesity or at least two components of MetS driven by waist circumference than they were in those with none. Stepwise linear regression results also showed that serum total OC was partially explained by age, gender, waist-to-hip ratio, and fasting glucose.

CONCLUSIONS

This study supported a negative association between serum total OC and adiposity in children. OC may be associated with childhood central obesity; however, further research using more accurate measurements is needed to identify the association between these variables.

Relationships between preptin and osteocalcin in obese, overweight, and normal weight adults

Preptin is an endocrine peptide secreted from pancreatic β cells; it acts as a physiological amplifier of glucose-mediated insulin secretion. Osteocalcin, secreted by osteoblasts, is also involved in the regulation of body energy in that it modulates fat and glucose metabolism. The aim of this study was to investigate circulating preptin and osteocalcin levels and the possible association between them in obese and overweight adults. A total of 100 obese-overweight adults and 50 healthy controls matched for age and sex were enrolled in this study. Anthropometric measurements were taken and fasting glucose, insulin, homeostasis model assessment of insulin resistance (HOMA-IR), lipid profile, preptin, and osteocalcin were assessed. Preptin was significantly higher in obese and overweight subjects than in controls, whereas osteocalcin was significantly lower. In multiple regression analysis, preptin was independently influenced by waist circumference (WC) (β = 3.75, P = 0.03), fasting insulin (β = 4.77, P = 0.01), HOMA-IR (β = 8.21, P = 0.003), and osteocalcin (β = -28.41, P = 0.04). Osteocalcin was independently influenced by body mass index (β = -1.46, P = 0.05), WC (β = -2.04, P = 0.03), fasting insulin (β = -2.69, P = 0.02), HOMA-IR (β = -0.19, P = 0.006), and triglyceride (β = -4.54, P = 0.001). In conclusion, elevated serum preptin and decreased osteocalcin concentrations, together with insulin resistance, are associated with obesity and overweight. Serum preptin is also independently associated with osteocalcin, which may explain, at least in part, the crosstalk between bone and the β cells of the pancreas.

Bone as an endocrine organ relevant to diabetes

There are well-established associations between diabetes and fracture risk and yet the mechanism underlying these associations are controversial. Guided by a series of mouse studies, a specific form of the bone protein, osteocalcin, was proposed to be the mechanistic link between these two chronic diseases. Translation to humans initially appeared elusive in part because serum concentrations of osteocalcin are a biomarker of bone turnover and not necessarily specific to the biology of this protein. The suitability of the mouse model for the study of osteocalcin as a therapeutic target also appears ambiguous. With greater discrimination of the different forms of osteocalcin present in circulation and inclusion of multiple measures of bone turnover, evidence currently does not support osteocalcin as a protein critical to the diabetes and fracture association in humans.

Bone health and risk factors of cardiovascular disease--a cross-sectional study in healthy young adults

Objective

Both osteoporosis and cardiovascular disease (CVD) are diseases that comprise a growing medical and economic burden in ageing populations. They share many risk factors, including ageing, low phy-sical activity, and possibly overweight. We aimed to study associations between individual risk factors for CVD and bone mineral density (BMD) and turnover markers (BTMs) in apparently healthy cohort.

Design

A cross-sectional assessment of 155 healthy 32-year-old adults (74 males) was performed for skeletal status, CVD risk factors and lifestyle factors.

Methods

We analysed serum osteocalcin, procollagen I aminoterminal propeptide (P1NP), collagen I carboxy-terminal telopeptide (ICTP) and urine collagen I aminoterminal telopeptide (U-NTX), as well as serum insulin, plasma glucose, triglyceride and HDL-cholesterol levels. BMD, fat and lean mass were asses-sed using DXA scanning. Associations were tested with partial correlations in crude and adjusted mo-dels. Bone status was compared between men with or without metabolic syndrome (defined according to the NCEP-ATPIII criteria) with multivariate analysis.

Results

Osteocalcin and P1NP correlated inversely with insulin (R = −0.243, P = 0.003 and R = −0.187, P = 0.021) and glucose (R = −0.213, P = 0.009 and R = −0.190, P = 0.019), but after controlling for fat mass and lifestyle factors, the associations attenuated with insulin (R = −0.162, P = 0.053 and R = −0.093, P = 0.266) and with glucose (R = −0.099, P = 0.240 and R = −0.133, P = 0.110), respectively. Whole body BMD associated in-versely only with triglycerides in fully adjusted model. In men with metabolic syndrome, whole body BMD, osteocalcin and P1NP were lower compared to healthy men, but these findings disappeared in fully adjusted model.

Conclusions

In young adults, inverse associations between BTM/BMD and risk factors of CVD appeared in crude models, but after adjusting for fat mass, no association continued to be present. In addition to fat mass, lifestyle factors, especially physical activity, modified the associations between CVD and bone charac-teristics. Prospective studies are needed to specify the role of mediators and lifestyle factors in the prevention of CVD and osteoporosis.

Glucocorticoids and bone: local effects and systemic implications

Glucocorticoids (GCs) are highly effective in the treatment of inflammatory and autoimmune conditions but their therapeutic use is limited by numerous adverse effects. Recent insights into the mechanisms of action of both endogenous and exogenous GCs on bone cells have unlocked new approaches to the development of effective strategies for the prevention and treatment of GC-induced osteoporosis. Furthermore, topical studies in rodents indicate that the osteoblast-derived peptide, osteocalcin, plays a central role in the pathogenesis of GC-induced diabetes and obesity. These exciting findings mechanistically link the detrimental effects of GCs on bone and energy metabolism. In this article we review the physiology and pathophysiology of GC action on bone cells, and discuss current and emerging concepts regarding the molecular mechanisms underlying adverse effects of GCs such as osteoporosis and diabetes.

Serum osteocalcin is significantly related to indices of obesity and lipid profile in Malaysian men

BACKGROUND AND AIM

Recent studies revealed a possible reciprocal relationship between the skeletal system and obesity and lipid metabolism, mediated by osteocalcin, an osteoblast-specific protein. This study aimed to validate the relationship between serum osteocalcin and indices of obesity and lipid parameters in a group of Malaysian men.

METHODS

A total of 373 men from the Malaysian Aging Male Study were included in the analysis. Data on subjects' demography, body mass index (BMI), body fat (BF) mass, waist circumference (WC), serum osteocalcin and fasting lipid levels were collected. Bioelectrical impendence (BIA) method was used to estimate BF. Multiple linear and binary logistic regression analyses were performed to analyze the association between serum osteocalcin and the aforementioned variables, with adjustment for age, ethnicity and BMI.

RESULTS

Multiple regression results indicated that weight, BMI, BF mass, BF %, WC were significantly and negatively associated with serum osteocalcin (p < 0.001). There was a significant positive association between serum osteocalcin and high density lipoprotein (HDL) cholesterol (p = 0.032). Binary logistic results indicated that subjects with low serum osteocalcin level were more likely to be associated with high BMI (obese and overweight), high BF%, high WC and low HDL cholesterol (p < 0.05). Subjects with high osteocalcin level also demonstrated high total cholesterol level (p < 0.05) but this association was probably driven by high HDL level. These variables were not associated with serum C-terminal of telopeptide crosslinks in the subjects (p > 0.05).

CONCLUSION

Serum osteocalcin is associated with indices of obesity and HDL level in men. These relationships should be validated by a longitudinal study, with comprehensive hormone profile testing.

Serum osteocalcin is associated with improved metabolic state via adiponectin in females versus testosterone in males. Gender specific nature of the bone-energy homeostasis axis

OBJECTIVE

The osteoblast-derived protein osteocalcin (OCN) is known to be involved in glucose metabolism by increasing adiponectin secretion from adipocytes. Recently, OCN was also found to enhance testosterone production in mouse testes, suggesting that OCN effects on energy metabolism may be mediated through testosterone. Our aim was to assess a possible gender difference in the metabolic effect of OCN in humans.

METHODS

We included 135 women and 155 men exhibiting changes in glucose tolerance in our study. Oral and intravenous glucose tolerance tests (OGTT and IVGTT, respectively) and a hyperinsulinemic normoglycemic clamp were performed. For clamp indices, whole body (M1) and muscle (M2) glucose uptake values were used. Leptin, adiponectin serum lipid, lipoprotein, total serum OCN and testosterone levels, and body composition were determined.

RESULTS

Higher OCN values were associated with improving metabolic state in both genders. Adiponectin and OCN correlated significantly only in females (r=+0.254, p=0.0029), while in men, testosterone and OCN values showed a significant positive correlation (r=+0.243, p=0.0023), independent of age, BMI, HbA1c and body composition. In women, adiponectin was confirmed by feature selection analysis as being an independent determinant of OCN, in addition to age and three of the IVGTT glucose values. In men, besides M1, BMI, M2, leptin, body fat percent, and the 90-minute OGTT glucose reading testosterone, but not adiponectin were identified as independent contributors for OCN.

CONCLUSION

We confirmed the 'classic' adiponectin-mediated insulin-sensitising effect of OCN only in females. In men, a testosterone-mediated OCN metabolic effect is more likely.

Ideal cardiovascular health in young adult populations from the United States, Finland, and Australia and its association with cIMT: the International Childhood Cardiovascular Cohort Consortium

BACKGROUND

Goals for cardiovascular (CV) disease prevention were set by the American Heart Association in 2010 for the concept of CV health. Ideal CV health is defined by 7 CV health metrics: blood pressure, glucose, cholesterol, body mass index, and physical activity on recommended levels; nonsmoking; and a healthy diet. We studied the prevalence of ideal CV health and its associations with ultrasonographically measured carotid intima-media thickness (cIMT) cross-sectionally in 5 international populations.

METHODS AND RESULTS

Prevalence of ideal CV health was assessed among 5785 young adults (age, 36.6 ± 3.2 years) comprising 335 participants from the Minneapolis Childhood Cohort Studies (Minnesota), 723 from the Princeton Follow-up Study, 981 from the Bogalusa Heart Study (BHS), 1898 from the Cardiovascular Risk in Young Finns Study (YFS), and 1848 from the Childhood Determinants of Adult Health Study (CDAH). Only 1% of the participants had all 7 ideal CV health metrics. The number of ideal CV health metrics associated inversely with cIMT in the 4 cohorts in which cIMT was available: for each additional ideal CV health metric, cIMT was 12.7 μm thinner in Minnesota (P=0.0002), 9.1 μm thinner in BHS (P=0.05), 10.4 μm thinner in YFS (P<0.0001), and 3.4 μm thinner in CDAH (P=0.03).

CONCLUSIONS

The number of ideal CV health metrics was inversely associated with cIMT in the cohorts in which cIMT was available, indicating that ideal CV health metrics are associated with vascular health at the population level. Ideal CV health was rare in this large international sample of young adults, emphasizing the need for effective strategies for health promotion.

Association between Osteocalcin, Metabolic Syndrome, and Cardiovascular Risk Factors: Role of Total and Undercarboxylated Osteocalcin in Patients with Type 2 Diabetes

Studies have demonstrated that total osteocalcin (TOC) is associated with metabolic syndrome (MetS) and therefore might influence the risk of cardiovascular disease in humans. Undercarboxylated osteocalcin (uOC) regulates insulin secretion and sensitivity in mice, but its relation to MetS in humans is unclear. We aimed to determine whether uOC is related to MetS and/or its individual components and other cardiovascular risk factors in patients with type 2 diabetes mellitus (T2DM), and whether TOC and uOC have utility in predicting the cardiovascular risk. We studied 203 T2DM patients with and without MetS. MetS was defined based on the NCEP-ATP III criteria. A correlation analysis was performed between the three outcome variables: (i) TOC, (ii) uOC, and (iii) carboxylated osteocalcin (cOC) and MetS components and other cardiovascular risk factors. Both TOC and uOC were significantly lower in patients with MetS compared to those without MetS, independent of body mass index. In patients with MetS, uOC was significantly and positively correlated with HDL cholesterol, while TOC was significantly and negatively correlated with serum triglycerides. We report for the first time that uOC is related to lipid indices in patients with T2DM. Further studies are necessary to determine whether uOC can be utilized for cardiovascular risk assessments in these patients.

Endocrine actions of osteocalcin

Osteocalcin is the most abundant noncollagenous protein of bone matrix. Once transcribed, this protein undergoes posttranslational modifications within osteoblastic cells before its secretion, including the carboxylation of three glutamic residues in glutamic acid, which is essential for hydroxyapatite binding and deposition in the extracellular matrix of bone. Recent provocative data from experimental observations in mice showed that the circulating undercarboxylated fraction of osteocalcin increases insulin secretion and sensitivity, lowers blood glucose, and decreases visceral fat in both genders, while it enhances testosterone production by the testes in males. Moreover, both total and undercarboxylated osteocalcins increase following physical activity with potential positive effects on glucose tolerance. Despite that these evidences have been only in part confirmed in humans, further prospective investigations are needed to definitively establish the endocrine role of osteocalcin both in the general population and cohorts of patients with diabetes or other metabolic disorders.