| Objective: There is an increasing prevalence of osteoporosis in type 2 diabetes mellitus nowadays. For the substantial morbidity and mortality of osteoporosis and T2DM in the elderly, it becomes the medical and social focus to preventing and curing osteoporosis in T2DM as early as possible. The type 2 diabetic osteoporosis is a skeletal complication with a complex mechanism which remains unclear. Someone had reported that many adipose cytokines might be involved in the occurrence and development of type 2 diabetic osteoporosis.Adipose tissue is not only an energy storage organs, but also an endocrine organs to regulate the body’s hormone, metabolism and inflammation. It can secrete a variety of hormones and cytokines. These secreted proteins are named adipose cytokines, which include leptin, adiponectin, resistin, tumor necrosis factor-α(TNF-α), secreted frizzled-related protein 5(Sfrp5), adipocyte fatty acid-binding protein, etc. Adipose cytokines can matain the energy balance, and participate in inflammation, coagulation, fibrinolytic, insulin resistance, diabetes and atherosclerosis. Recently, it is found that adipose cytokines were not only associated with diabetes, but also related with osteoporosis.Apelin is a newly found adipose cytokine, originated not only from adipose tissue, but also from many other tissues and secreted to blood vessels. It was firstly identified as the endogenous ligand for the orphan G protein-coupled receptor, and widely distributed in human body. Nowadays, it has been demonstrated that apelin is not only an adipocytokine involved in the glucose and lipid metabolism by means of autocrine and paracrine, but also a vasoactive peptide to contract renin-angiotensin system and promote angiogenesis, which can influence the progression of diabetic macroangiopathy and microangiopathy; meantime, apelin is a neuropeptide to affect the progression of diabetic neuropathy. More importently, Apelin is an islete peptide for regulating the secretion and function of insulin. Apelin is closely related to diabetes mellitus, and have become a new promising target for preventing and treating diabetes mellitus.In this context, the objectives of our study were to evaluate serum apelin-13 levels in T2DM patients and to analyze its relationships with bone BMD and related clinical factors, so that we can provide certain basis for the study of clinical trials in the prevention and treatment of osteoporosis in T2DM with the certain adipose cytokine, apelin-13.Methods: A total of 87 T2DM inpatients were included in the Third Hospital of Hebei Medical University Endocrinology Department from September 2014 to December 2014. All subjects were measured bone mineral density(BMD) at lumbar vertebra(L2-L4), both femurs(neck, ward, great rochanter, intertrochanter) by Dual Energy X-ray Absorptiometry(DEXA). According to the diagnostic criteria of the WHO, all subjects were divided into three groups(normal BMD group, osteopenia group and osteoporosis group). We recorded the gender, age, height, weight, duration and other related information of patients, as well as calculating body mass index(BMI), and glycosylated hemoglobin(Hb Alc). By using enzyme-linked immunosorbent method(enzyme-linked immunosorbent assay, ELISA), we evaluated serum apelin-13 level, and by using radioimmunoassay(RIA), we measured serum 25(OH)D3, PINP, and ICTP. All data were analyzed by SPSS16.0.Results:1 The discrepancies of age, height, weight, and serum PINP and ICTP levels among the three groups were significant(p<0.05). And there were no significant differences of BMI, duration and Hb Alc in the three groups.2 The multiple regression analysis between BMD and age, gender, BMI, duration, glycosylated hemoglobin, apelin-13, and 25(OH)D3: Apelin-13 was positively correlated with double hip, L2 and L3 BMD; Hb A1 c was negatively correlated with R-ward BMD; 25(OH)D3 was positively correlated with R-ward, R-intertro, L-Intertro, L2, L3, and L4 BMD; BMI was positively correlated with L4 BMD.3 Serum apelin-13 level was statistically significant between three groups(p < 0.001). Furthermore, the serum apelin-13 level of osteoporosis group was lower than that of osteopenia group, and normal BMD group.4 The analysis of apelin-13 serum levels’ correlation with age, gender, BMI, duration, Hb Alc, 25(OH)D3, BMD and bone turnover markers were conducted in three groups, with a result as follows. In normal BMD group: serum apelin-13 levels were positively correlated with PINP, weight, and BMD. In osteopenia group: serum apelin-13 levels are positively related with 25(OH)D3, and negatively correlated with ICTP.Conclusions:1 The BMD of T2DM patients were influenced by apelin-13, 25(OH)D3, BMI, and Hb A1 c, but had no significant correlation with age, sex, duration, glycosylated hemoglobin2 In T2DM patients, apelin-13, the adiponectin, influenced bone metabolism, including bone formation and bone resorption.3 Among the three groups in T2DM, the serum Apelin-13, 25(OH)D3, PINP levels and BMI are the lowest. Meanwhile, the serum ICTP levels and the average age are the highest in the osteoporosis group. |
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