en 31379997 <p>Background: Type 2 Diabetes Mellitus (T2DM) is a serious problem in the world. 5-Hydroxytryptamine (5-HT, serotonin) plays an important role in obesity, glucose control and insulin resistance. The polymorphism of the serotonin transporter gene linked promoter region (5-HTTLPR) might influence 5-HTT expression and serotonin uptake. The polymorphism results in two alleles of L (Long) and S (Short). The aim of the present study was to evaluate the association between 5-HTTLPR genotypes in type 2 diabetes mellitus (T2DM), obesity as well as serum biochemical profiles in Iranian population from 2012 until 2015.<br /> Methods: 180 patients with T2DM and 180 controls were selected and the frequency of S and L alleles was determined by PCR. Then, the relationship between genotypes, body mass index (BMI) and serum biochemical variables was investigated.<br /> Results: The frequency of S and L alleles in experimental and control groups was the same [for the L allele p=0.754, OR (95%CI)=1.103 (0.597 to 2.041) and for the S allele p=0.906, OR (95%CI)=(0.490 to 1.676)]. However, the mean triglyceride, cholesterol, LDL-C, systolic and diastolic blood pressure levels in the diabetic subjects with LL genotype were significantly higher than LS and SS genotypes (p&lt;0.001) in this population.<br /> Conclusion: The L allele of 5-HTTLPR was related to the increased serum lipids and blood pressure in the diabetic patients. However, there was no relationship between the polymorphism of 5-HTTLPR L/S and T2DM in Iranian population.&nbsp;</p> 5-HTT gene, 5-HTTLPR polymorphism, Serotonin, Type 2 diabetes mellitus 239 244 https://www.ajmb.org/En/Article.aspx?id=10381 https://www.ajmb.org/PDF/En/FullText/10381.pdf AzizehAsadzadehDepartment of Biology, University of Nourdanesh Institute of Higher Education, Meymeh, Isfahan, Iran11455HooriaSeyedhosseini GhahehYoung Researchers and Elites Club, Science and Research Branch, Islamic Azad University, Tehran, Iran11456FatemehSholehvarDepartment of Biology, Faculty of Science, Zand Institute of Higher Education, Shiraz, Iran11457MohammadaliTakhshidDiagnostic Laboratory Sciences and Technology Research Center, School of Paramedical Sciences, Shiraz University of Medical Sciences, Shiraz, Iran11458Mohammad MehdiNaghizadehNoncommunicable Diseases Research Center, Fasa University of Medical Sciences, Fasa, Iran11459