Vitamin D Status and Incident Type 2 Diabetes

描述（由申请人提供）：2型糖尿病的发病率在全国和全球范围内以惊人的速度增加，仅在美国每年就诊断出超过100万例新病例。虽然减肥已被证明可以成功地延缓糖尿病，但很难长期实现和维持。因此，迫切需要识别与体重无关的环境和容易改变的危险因素，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，根据动物和人类研究，包括我们自己的初步观察数据，怀疑它是糖尿病风险的调节剂。然而，我们对维生素D对糖尿病风险的临床影响程度的认识存在重大差距。目前，缺乏数据限制了维生素D作为预防2型糖尿病的可行营养干预措施的有效性。这项研究的中心假设是，维生素D不足是2型糖尿病发展的危险因素。我们计划通过对正在进行的观察性研究进行辅助研究来验证我们的主要假设并实现本申请的目的，以评估维生素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状态，如血清25 OHD水平，与2型糖尿病风险呈负相关。将在一项大型前瞻性队列（护士健康研究）（600例2型糖尿病病例和600例对照-按年龄和抽血季节匹配）的健康女性中进行巢式病例对照研究设计，量化这种关联。我们将调整已测量的潜在糖尿病混杂因素（人口统计学，医学和营养），我们还将检查BMI或钙摄入量是否会改变这种关联。

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.