Journal of Research in Pharmacy Practice Journal of Research in Pharmacy Practice / Oct-Dec 2012 / Vol 1 / Issue 2 60 Original Article Does the intramuscular injection of vitamin D increase insulin resistance? Bijan Iraj 1 , Ashraf Aminorroaya 1 , Massoud Amini 1 ABSTRACT Objective: Considering the physiologic roles of vitamin D on insulin regulation, the effects of vitamin D treatment on insulin sensitivity and resistance indexes and beta cell function in pre‑diabetic vitamin D deicient patients were investigated. Methods: In a randomized open clinical trial, 61 pre‑diabetic vitamin D deicient patients who were the irst degree relatives of type 2 diabetic patients, were enrolled and randomized into three groups (A, B and C). Group A (n = 21) were treated with intramuscular injection of 300,000 units of vitamin D at the beginning of the study and one month later. In group B (n = 20), injection of vitamin D plus 500 mg/d calcium and in group C (n = 20), just calcium was administered for two months. At baseline and two months later, oral glucose tolerance test was done. Homeostasis Model of Assessment‑Insulin Resistance (HOMA‑ IR), insulin resistance index, Homeostasis Model of Assessment‑B (HOMA‑B) which is a beta cell function index, and Matsuda index, an insulin sensitivity index, were calculated and compared before and after intervention and between three groups. Findings: In vitamin D treated groups (A + B), the mean (SD) of HOMA‑IR increased from 2.46 (1.36) to 3.1 (2.3) (P = 0.02), and Matsuda index decreased from 11 (3) to 9.0 (2.3) (P = 0.001). Conclusion: Injection of vitamin D increased insulin resistance and decreased insulin sensitivity indexes. Keywords: Vitamin D; pre‑diabetic state; diabetes mellitus type 2; oral glucose tolerance test INTRODUCTION The presence of vitamin D receptor and vitamin D depended calcium binding protein on the beta cells may express some physiological roles for vitamin D on the regulation of insulin secretion. Direct efect of vitamin D is stimulation of insulin receptor expression on β cells and its indirect action is the regulation of extra cellular calcium and maintaining of normal calcium inlux to these cells. [1‑4] The relationship between low concentration of 25(OH) D and insulin resistance has been previously reported in several studies. [5,6] It is well known that pre‑diabetic patients have increased insulin resistance and decreased insulin sensitivity. They are high risk people for progression to type 2 diabetes (T2DM). Therefore, they are a suitable population target for primary prevention program of diabetes. [7] It is expected that vitamin D treatment in vitamin D deiciency pre‑diabetic patients can improve insulin sensitivity and decrease insulin resistance indexes. Considering the role of vitamin D deiciency on insulin resistance, vitamin D treatment may prevent the progression vitamin D deicient pre‑diabetic to T2DM patients. In order to investigate this hypothesis, we administered intramuscular injection of vitamin D with and without oral calcium to vitamin D deicient pre‑diabetic patients. Received: April 2012 Accepted: July 2012 Corresponding author: Prof. Massoud Amini E‑mail: emrc@mui.ac.ir Access this article online Website: www.jrpp.net DOI: *** 1 Department of Internal Medicine and Endocrinology, Isfahan Endocrine and Metabolism Research Center, Isfahan University of Medical Sciences, Isfahan, Iran [Downloaded free from http://www.jrpp.net on Monday, March 25, 2013, IP: 176.102.240.148] || Click here to download free Android application for this journal