Levels of serum vaspin and tumor necrosis factor-α in patients with type 2 diabetes mellitus in relation to kidney function and glycemic control

Abstract

Background Diabetes mellitus type 2 (T2DM) is a metabolic disorder that is characterized by high blood glucose in the context of insulin resistance and relative insulin deficiency. Vaspin (visceral adipose tissue-derived serpin) is a member of the broadly distributed serpin (a protein superfamily of serine protease inhibitors of ∼500 genes) and is identical to serpin A12. The upregulation of vaspin can improve insulin resistance. Thus, identification of the protease inhibited by vaspin may lead to the development of novel strategies in the treatment of diabetes and insulin resistance. In patients with chronic kidney disease, the levels of vaspin appear to increase mostly because of reduced renal metabolism of vaspin. Tumor necrosis factor-α (TNF-α) is a cytokine involved in systemic inflammation. Its increased production has been observed in adipose tissue, and it has been implicated as a causative factor in obesity-associated insulin resistance, the pathogenesis of T2DM, and the development of diabetic nephropathy (DN) through several mechanisms. The association of T2DM patients (with and without impaired renal function) with serum vaspin and TNF-α levels is not clearly understood. This study aimed to evaluate the levels of vaspin and tumor necrosis factor (TNF) in T2DM patients and compare their levels with impairment in renal function in T2DM to determine whether circulating vaspin and TNF could be a biomarker of DN. Patients and methods This case–control observational prospective study was conducted on 73 patients with T2DM classified into two groups; group I included 20 T2DM patients with reduced renal function, and group II included 53 T2DM patients with normal renal function. The studied groups were recruited from the Diabetic Unit Outpatient Clinic, Department of Internal Medicine, Sohag University Hospitals, from December 2014 to December 2015. T2DM was diagnosed according to the American Diabetes Association Criteria. Totally, 12 age and sex matched apparently healthy individuals who served as the control group (group III) were enrolled in the study. The study was approved by the ethical committee of Faculty of Medicine, Sohag University, and written informed consent was obtained from each participant. All participants were subjected to thorough history taking, full clinical examination, and anthropometric measurements, including weight, height, and BMI. In addition, peripheral hemogram, random blood glucose evaluation, HbA1c determination, liver function tests, kidney function tests, lipid profile, and serum vaspin and serum TNF-α evaluation were carried out. Results In essence, significant correlations of vaspin and TNF were found with age of T2DM patients, hypertension, BMI, and lipid profile, but not with HbA1c. Moreover, higher levels of vaspin and TNF-α were significantly correlated with the degree of impaired renal function in T2DM patients. Notably, multivariate linear regression shows that BMI and age are negatively correlated with vaspin but not with TNF-α levels in T2DM patient with more impaired renal function. Conclusion Strict monitoring of T2DM can reduce the morbidity and mortality rate and will also improve the quality of life of diabetic patients. The association of renal insufficiency due to diabetes mellitus with serum vaspin and TNF-α levels is not clearly understood. However, vaspin may be beneficial as a positive biomarker for T2DM patients with impaired renal function and can be considered as a new prognostic marker for DN. Large studies are required to establish vaspin and TNF-α efficacy and safety in T2DM.