Combined Effects of Vitamin D Supplementation and Endurance Exercise Training on Insulin Resistance in Newly Diagnosed type 2 Diabetes Mellitus Patients with Vitamin D Deficiency : Study Protocol for a Randomized Controlled Trial
Abstract BackgroundAlthough approximately 50% of Chinese T2DM patients have vitamin D deficiency, studies regarding vitamin D supplementation on IR have mainly focused on non-Asians. Endurance exercise training (ET) enhances insulin-mediated glucose metabolism, which plays a critical role in T2DM prevention and control. However, the combined effects of vitamin D supplementation and ET on IR in T2DM patients are unclear.Methods and analysisWe propose a randomized controlled trial among 60 T2DM patients with vitamin D deficiency to evaluate the combined effects of vitamin D supplementation and endurance training on IR. The participants will be randomly allocated to the vitamin D group, vitamin D combined with exercise training group, exercise training group, and control group (CG) using a computer-generated random number sequence. At baseline, participants will undergo a medical review, anthropometric measurements, dual X-ray absorptiometry, a 75-g oral glucose tolerance test, ankle-brachial index measurements, and physical fitness measurements and will complete related lifestyle questionnaires. In a 3-month intervention period, vitamin D intervention group will receive a dose of 1000IU daily; exercise group will perform a 1-hour endurance exercise 3 times per week (maximal heart rate, 60%–80%), and the control group will receive apparently identical tablets. Additionally, all participants will be advised to maintain their normal diet and physical activities during the intervention. All measurements will be repeated at 3-month follow-up after the intervention with the primary outcome measure expressed as a change from baseline in insulin sensitivity and secretion. Secondary outcome measures will compare the changes in anthropometry, ankle-brachial index, and physical fitness factors. Data will be managed and analyzed using the Statistical Package for the Social Sciences.DiscussionThis is the first study to conduct a randomized trial to clearly determine the independent and combined effects of vitamin D supplementation and endurance exercise trial on IR in Chinese T2DM patients as measured by OGTT. The findings from the proposed study will not only provide new evidences that vitamin D supplementation plays an important role in reducing IR but also develop a simple and efficient method to improve IR and associated metabolic diseases for T2DM patients.Trial registrationChinese Clinical Trial Registry, ChiCTR1800015383, Registered 28 March 2018, http://www.chictr.org.cn