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.

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.

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.

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.

Effect of triptolide on expression of oxidative carbonyl protein in renal cortex of rats with diabetic nephropathy.

The traditional Chinese medicine (Tripterygium wilfordiiHook.f., TWH) has been clinically used to treat primary and secondary renal diseases and proteinuria for nearly 40 years. However, there is a rare literature about the effect of triptolide (the main active ingredient of TWH) on the expression of oxidative carbonyl protein (OCP) in diabetic nephropathy (DN). This study aimed to provide experimental evidence for triptolide treatment on DN through its effect on the expression of OCP, in order to investigate the effects of triptolide on the expression of OCP in rats with DN. Sixty SD rats were randomly divided into five groups: control group, high-dose triptolide (Th) group, low-dose triptolide (Tl) group, DN model group, and positive control (benazepril) group. The DN model was established using streptozotocin. Urinary protein excretion, fasting blood glucose (FBG), superoxide dismutase (SOD) in renal homogenate, malondialdehyde (MDA) in renal homogenate and renal nitrotyrosine by immunohistochemistry, and the expression of OCP by oxyblotimmune blotting were detected. In the DN model group, rat urinary protein excretion and renal MDA were significantly increased, while renal SOD significantly decreased and nitrotyrosine expression was obviously upregulated in the kidney. After triptolide treatment, 24-h urinary protein excretion (61.96±19.00 vs. 18.32±4.78 mg/day, P<0.001), renal MDA (8.09±0.79 vs. 5.45±0.68 nmol/L, P<0.001), and nitrotyrosine expression were decreased. Furthermore, renal OCP significantly decreased, while renal SOD (82.50±19.10 vs. 124.00±20.52 U/L, P<0.001) was elevated. This study revealed that triptolide can down-regulate the expression of OCP in the renal cortex of DN rats.

Effects and clinical significance of pentoxifylline on the oxidative stress of rats with diabetic nephropathy.

Diabetic nephropathy (DN) is a common and serious clinical complication of diabetes and presently there are no effective ways to prevent its occurrence and progression. Recent studies show that pentoxifylline (PTX) can improve renal hemodynamics, reduce urinary protein excretion, and alleviate or delay renal failure in DN patients. In this study, we focused on the anti-oxidative stress effect of PTX on alleviating renal damages of DN using rat models. DN rats were established with injection of streptozotocin. Blood glucose, urinary protein excretion, serum cystatin C, renal biopsy, superoxide dismutase (SOD) and malondialdehyde (MDA) in serum and renal homogenate and renal nitrotyrosine levels were analyzed before and 12 weeks after the treatment of PTX. Before treatment, all the DN rats had elevated blood glucose, increased urinary protein excretion and elevated serum cystatin C. Morphologically, DN rats exhibited renal tissue damages, including swelling and fusions of foot processes of podocytes under electron microscope. Masson staining revealed blue collagen deposition in glomeruli and renal interstitium. With treatment of PTX, symptoms and renal pathological changes of DN rats were alleviated. Furthermore, the MDA levels were increased and the SOD levels were decreased in the serum and kidneys of DN rats, and these changes were reversed by PTX. The expression of nitrotyrosine was up-regulated in DN rat model and down-regulated by PTX, indicating that PTX was able to inhibit oxidative reactions in DN rats. PTX could alleviate renal damage in DN, which may be attributable to its anti-oxidative stress activity.

Effect of Triptolide on Expression of Oxidative Carbonyl Protein in Renal Cortex of Rats with Diabetic Nephropathy / 华中科技大学学报（医学）（英德文版）

The traditional Chinese medicine (Tripterygium wilfordiiHook.f.,TWH) has been clinically used to treat primary and secondary renal diseases and proteinuria for nearly 40 years.However,there is a rare literature about the effect of triptolide (the main active ingredient of TWH) on the expression of oxidative carbonyl protein (OCP) in diabetic nephropathy (DN).This study aimed to provide experimental evidence for triptolide treatment on DN through its effect on the expression of OCP,in order to investigate the effects of triptolide on the expression of OCP in rats with DN.Sixty SD rats were randomly divided into five groups:control group,high-dose triptolide (Th) group,low-dose triptolide (T1) group,DN model group,and positive control (benazepril) group.The DN model was established using streptozotocin.Urinary protein excretion,fasting blood glucose (FBG),superoxide dismutase (SOD) in renal homogenate,malondialdehyde (MDA) in renal homogenate and renal nitrotyrosine by immunohistochemistry,and the expression of OCP by oxyblotimmune blotting were detected.In the DN model group,rat urinary protein excretion and renal MDA were significantly increased,while renal SOD significantly decreased and nitrotyrosine expression was obviously upregulated in the kidney.After triptolide treatment,24-h urinary protein excretion (61.96±19.00 vs.18.32±4.78 mg/day,P＜0.001),renal MDA (8.09±0.79 vs.5.45±0.68 nmol/L,P＜0.001),and nitrotyrosine expression were decreased.Furthermore,renal OCP significantly decreased,while renal SOD (82.50±19.10 vs.124.00±20.52 U/L,P＜0.001) was elevated.This study revealed that triptolide can down-regulate the expression of OCP in the renal cortex of DN rats.