Positive association of glucagon with bone turnover markers in type 2 diabetes: A cross-sectional study.

AIMS: The osteo-metabolic changes in type 2 diabetes (T2D) patients are intricate and have not been fully revealed. It is not clear whether glucagon is entirely harmful in the pathogenesis of diabetes or a possible endocrine counter-regulation mechanism to reverse some abnormal bone metabolism. This study aimed to investigate the association between glucagon and bone turnover markers (BTMs) in T2D patients. METHODS: A total of 3984 T2D participants were involved in a cross-sectional study in Shanghai, China. Serum glucagon was measured to elucidate its associations with intact N-terminal propeptide of type I collagen (P1NP), osteocalcin (OC), and ß-C-terminal telopeptide (ß-CTX). Glucagon was detected with a radioimmunoassay. Propeptide of type I collagen, OC, and ß-CTX were detected using chemiluminescence. The diagnosis of T2D was based on American Diabetes Association criteria. RESULTS: The concentration of glucagon was positively correlated with two BTMs [OC-ß: 0.034, 95% CI: 0.004, 0.051, p = 0.024; CTX-ß: 0.035, 95% CI: 0.004, 0.062, p = 0.024]. The result of P1NP was [P1NP-regression coefficient (ß): 0.027, 95% CI: -0.003, 0.049, p = 0.083]. In the glucagon tertiles, P for trend of the BTMs is [P1NP: 0.031; OC: 0.038; CTX: 0.020], respectively. CONCLUSIONS: Glucagon had a positive effect on bone metabolism. The concentrations of the three BTMs increased as glucagon concentrations rose. This implied that glucagon might speed up skeletal remodelling, accelerate osteogenesis, and promote the formation of mature bone tissue. At the same time, the osteoclastic process was also accelerated, providing raw materials for osteogenesis to preserve the dynamic balance. In view of the successful use of single-molecule as well as dual/triple agonists, it would be feasible to develop a preparation that would reduce osteoporosis in diabetic patients.

FSH may mediate the association between HbA1c and bone turnover markers in postmenopausal women with type 2 diabetes.

INTRODUCTION: Recent studies in postmenopausal women have found associations of follicle-stimulating hormone (FSH) levels with both glucose metabolism and bone turnover. The objective of the study was to investigate whether FSH may contribute to suppressed bone turnover markers (BTMs) in postmenopausal women with type 2 diabetes (T2D). MATERIALS AND METHODS: 888 postmenopausal women with T2D, 352 nondiabetes (prediabetes plus normoglycemia) were included from the METAL study. HbA1c, sex hormones, 25-hydroxy vitamin D (25(OH)D), serum procollagen type I N-terminal propeptide (P1NP), and ß-C-terminal telopeptide (ß-CTX) were measured. RESULTS: P1NP and ß-CTX decreased in postmenopausal T2D women compared with nondiabetes controls (both p < 0.001). The major factors responsible for the changes in P1NP were HbA1c (ß = - 0.050, p < 0.001), 25(OH)D (ß = - 0.003, p = 0.006), FSH (ß = 0.001, p = 0.044) and metformin (ß = - 0.109, p < 0.001), for ß-CTX were HbA1c (ß = - 0.049, p < 0.001), body mass index (BMI) (ß = - 0.011, p = 0.005), 25(OH)D (ß = - 0.003, p = 0.003), FSH (ß = 0.002, p = 0.022) and metformin (ß = - 0.091, p = 0.001) in postmenopausal T2D women based on multivariate regression analysis. With the increase in HbA1c, FSH decreased significantly (p for trend < 0.001). Mediation analysis demonstrated that FSH partly mediated the suppression of LnP1NP and Lnß-CTX by HbA1c (ß = - 0.009 and - 0.010, respectively), and Lnß-CTX by BMI (ß = - 0.015) when multiple confounders were considered (all p < 0.05). CONCLUSION: HbA1c was the crucial determinant contributing to the suppression of BTMs. FSH might play a novel mediation role in BTM suppression due to HbA1c or BMI.

LDL in patients with subclinical hypothyroidism shows increased lipid peroxidation.

BACKGROUND: Population-based studies have demonstrated that subclinical hypothyroidism (SCH) is an independent risk factor for atherosclerosis (OR = 1.9). However, this connection cannot be entirely explained by dyslipidemia accompanied by SCH. Lipid peroxidation also plays an important role in the development of atherosclerosis. In this study, we aimed to evaluate oxidative stress in SCH patients, as measured according to concentrations of hydroxy-octadecadienoic acids (HODEs) and hydroxy-eicosatetraenoic acids (HETEs) in both plasma and low density lipoproteins (LDL). SUBJECTS AND METHODS: The concentrations of HODEs and HETEs in both LDL and plasma were examined in euthyroid (n = 10), mild SCH (4.5 ≤ TSH < 10 mU/L, n = 10), and significant SCH (TSH ≥ 10 mU/L, n = 10) subjects, using a liquid chromatograph-electrospray ionization- mass spectrometer. Then, we explored the relationship among LDL oxidation, TSH levels, and carotid intima-media thickness (IMT), a biomarker of subclinical atherosclerosis. RESULTS: Serum LDL-C levels and mean-IMT in the significant SCH group were higher than in the euthyroid group (p < 0.05). The HODE and HETE concentrations clearly increased in the significant SCH patients compared with the euthyroid subjects, but there was no difference between the mild SCH and euthyroid groups. Among all subjects, linear and significant positive correlations were identified between TSH and mean-IMT after adjustment for confounding factors (r = 0.480, p = 0.018). Both 9-HODE (r = 0.376, p = 0.041) and 13-HODE (r = 0.447, p = 0.013) in LDL were linearly and positively correlated with TSH. The concentrations of HODEs (both 9-HODE and 13-HODE) in LDL were much higher in the thickened IMT group than in the normal IMT group (p = .017 and 0.015, respectively). HODEs in LDL were also positively associated with mean-IMT. CONCLUSIONS: Our findings showed that lipid peroxidation was higher in the significant SCH patients than in the euthyroid subjects, which suggested that qualitative as well as quantitative changes in serum lipids resulting from SCH may add to atherosclerosis risk.

Diabetes Mellitus Type 2 Patients with Abdominal Obesity Are Prone to Osteodysfunction: A Cross-Sectional Study.

Introduction: The interaction between diabetes, obesity, and bone metabolism was drawing increasing public attention. However, the osteometabolic changes in diabetes mellitus type 2 (T2DM) patients with abdominal obesity have not been fully revealed. This study is aimed at investigating the association between abdominal obesity indices and bone turnover markers among T2DM participants. Methods: 4351 subjects were involved in the METAL study. Abdominal obesity indices included neck, waist, and hip circumference, visceral adiposity index (VAI), lipid accumulation product (LAP), waist-to-hip ratio (WHR), and Chinese visceral adiposity index (CVAI). They were applied to elucidate the nexus between ß-C-terminal telopeptide (ß-CTX), osteocalcin (OC), and intact N-terminal propeptide of type I collagen (P1NP). Results: Abdominal obesity indices were strongly negatively associated with ß-CTX and OC. Among males, five indices were negatively correlated with ß-CTX (BMI, WC, LAP, WHR, and CVAI) and OC (BMI, NC, WC, WHR, and CVAI). There were no significant associations with P1NP. Among females, all eight indices were negatively associated with ß-CTX. Seven indices were negatively related to OC (BMI, NC, WC, HC, LAP, WHR, and CVAI). The VAI was negatively correlated with P1NP. Conclusions: The present study demonstrated that in T2DM, abdominal obesity had an obviously negative correlation with bone metabolism. Abdominal obesity indices were significantly negatively associated with skeletal destruction (ß-CTX) and formation (OC). In routine clinical practice, these easily obtained indices could be used as a preliminary screening method and relevant factors for osteodysfunction incidence risk at no additional cost and may be of particular value for postmenopausal women in T2DM populations.

Novel Associations of Dyslipidaemia with Vitamin D and Bone Metabolism in Elderly Patients with Diabetes: A Cross-Sectional Study.

Objective: Little is known about whether diabetic dyslipidaemia contributes to increased bone fragility in patients with diabetes. This study aimed to explore the potential effects of dyslipidaemia on vitamin D and bone metabolism in elderly subjects with type 2 diabetes (T2D). Methods: A total of 1479 male patients and 1356 female patients 50 years or older with T2D were included in Shanghai, China. Lipid profiles, 25-hydroxyvitamin D (25(OH)D), serum procollagen type I N-terminal propeptide (P1NP), ß-C-terminal telopeptide (ß-CTX) and other parameters were measured. Principal component regression (PCR) and mediation analysis were used to estimate the associations of lipid profile, 25(OH)D and bone turnover levels. Results: Female patients presented with higher blood lipids, lower 25(OH)D, and higher P1NP and ß-CTX levels than male patients with T2D. TC was associated with P1NP in males and females (ß=0.056, P<0.05; ß=0.095, P<0.01, respectively), and 25(OH)D fully mediated the associations in males and mediated approximately 17.89% of the effects in females. LDL-C was associated with P1NP in males and females (ß=0.072 and 0.105 respectively, all P<0.01), and 25(OH)D mediated the relationships approximately 20.83% in males and 14.29% in females. TG was negatively associated with P1NP (in males, ß= -0.063, P<0.05; in females, ß= -0.100, P<0.01) and ß-CTX (in males, ß= -0.108; in females, ß= -0.128, all P<0.01) independent of 25(OH)D, while HDL-C was not associated with P1NP or ß-CTX in diabetic patients. Conclusion: Hypercholesterolemia and hypertriglyceridaemia might affect bone metabolism by distinguishing pathways in diabetes patients. Ameliorating lipid control in elderly diabetes patients, especially female patients, will benefit both vitamin D and bone metabolism.

Association of Insulin Resistance and ß-cell Function With Bone Turnover Biomarkers in Dysglycemia Patients.

Background: The interrelation between glucose and bone metabolism is complex and has not been fully revealed. This study aimed to investigate the association between insulin resistance, ß-cell function and bone turnover biomarker levels among participants with abnormal glycometabolism. Methods: A total of 5277 subjects were involved through a cross-sectional study (METAL study, http://www.chictr.org.cn, ChiCTR1800017573) in Shanghai, China. Homeostasis model assessment of insulin resistance (HOMA-IR) and ß-cell dysfunction (HOMA-%ß) were applied to elucidate the nexus between ß-C-terminal telopeptide (ß-CTX), intact N-terminal propeptide of type I collagen (P1NP) and osteocalcin (OC). ß-CTX, OC and P1NP were detected by chemiluminescence. Results: HOMA-IR was negatively associated with ß-CTX, P1NP and OC (regression coefficient (ß) -0.044 (-0.053, -0.035), Q4vsQ1; ß -7.340 (-9.130, -5.550), Q4vsQ1 and ß -2.885 (-3.357, -2.412), Q4vsQ1, respectively, all P for trend <0.001). HOMA-%ß was positively associated with ß-CTX, P1NP and OC (ß 0.022 (0.014, 0.031), Q4vsQ1; ß 6.951 (5.300, 8.602), Q4vsQ1 and ß 1.361 (0.921, 1.800), Q4vsQ1, respectively, all P for trend <0.001). Conclusions: Our results support that lower bone turnover biomarker (ß-CTX, P1NP and OC) levels were associated with a combination of higher prevalence of insulin resistance and worse ß-cell function among dysglycemia patients. It is feasible to detect bone turnover in diabetes or hyperglycemia patients to predict the risk of osteoporosis and fracture, relieve patients' pain and reduce the expenses of long-term cure.