Vitamin D Status and Incident Type 2 Diabetes

描述(申请人提供)：2型糖尿病的发病率正在以惊人的速度在全国和世界范围内增长，仅在美国每年就有100多万新确诊病例。虽然减肥已被证明在延缓糖尿病方面是成功的，但它很难实现并长期保持。因此，迫切需要识别体重非依赖的环境因素和易于修改的危险因素，以防止2型糖尿病发病率的增加。维生素D是一种营养因素，基于动物和人类的研究，包括我们自己的初步观察数据，它被怀疑是糖尿病风险的修饰物。然而，在我们对维生素D对糖尿病风险的临床影响的程度方面，我们的知识存在严重差距。目前，缺乏数据限制了维生素D作为一种可行的营养干预措施预防2型糖尿病的有效性。这项拟议研究的中心假设是，维生素D不足是发展为2型糖尿病的风险因素。我们计划通过一项正在进行的观察性研究的辅助研究来检验我们的主要假设，并实现这项应用的目标，该研究旨在评估维生素D状态与发生2型糖尿病风险之间的关联程度。工作假设是，维生素D的状态，如通过血清25OHD水平来衡量，与2型糖尿病的风险呈负相关。这种关联将在一个大型前瞻性队列中健康女性的嵌套病例对照研究设计中量化，这是一项名为护士健康研究的研究(600例T2 DM患者和600名对照--按年龄和抽血季节匹配)。我们将调整已经测量的潜在的糖尿病混杂因素(人口，医疗和营养)，我们还将检查这种关联是否被BMI或钙摄入量改变。

DESCRIPTION (provided by applicant): The incidence of type 2 diabetes mellitus is increasing at an alarming rate both nationally and worldwide with more than 1 million new cases per year diagnosed in the US alone. Although weight-loss has been shown to be successful in delaying diabetes, it is difficult to achieve and maintain long-term. Therefore, identification of weight-independent environmental and easily modified risk factors is urgently needed to prevent the increase in the incidence of type 2 diabetes. Vitamin D is a nutritional factor that has been suspected as a modifier of diabetes risk based on animal and human studies including our own preliminary observational data. However, there are critical gaps in our knowledge about the magnitude of the clinical effect of vitamin D on diabetes risk. Currently, this lack of data limits the usefulness of vitamin D as a feasible nutritional intervention for prevention of type 2 diabetes. The central hypothesis of the proposed study is that, vitamin D insufficiency is a risk factor for the development of type 2 diabetes. We plan to test our main hypothesis and accomplish the objectives of this application by pursuing an ancillary study to an ongoing observational study to assess the magnitude of the association between vitamin D status and risk of developing type 2 diabetes. The working hypothesis is that vitamin D status, as measured by serum 25OHD level, is inversely associated with type 2 diabetes risk. The association will be quantified in a nested case-control study design in healthy women in a large prospective cohort, the Nurses' Health Study (600 t2DM cases and 600 controls - matched by age and season of blood draw). We will adjust for potential diabetes confounders (demographic, medical and nutritional) that have been measured and we will also examine whether the association is modified by BMI or calcium intake.