OBJECTIVEIn observational studies, low serum 25-hydroxyvitamin D [25(OH)D] concentrations have been associated with insulin resistance and other risk factors for cardiovascular disease. RESEARCH DESIGN AND METHODSWe present 1-year data from an ongoing 5-year trial in 511 individuals with impaired fasting glucose (IFG) and/or impaired glucose tolerance (IGT) randomly assigned to 20,000 IU/week vitamin D3 or placebo. An oral glucose tolerance test was performed at baseline and after 1 year. RESULTSMean baseline serum 25(OH)D was 59.9 nmol/L and 61.1 nmol/L in the vitamin D and placebo groups, respectively, and increased by 45.8 nmol/L and 3.4 nmol/L, respectively. With adjustment for baseline concentrations, no differences in measures of glucose metabolism, insulin secretion or sensitivity, blood pressure, or hs-CRP were found after 1 year. There was a slight, but significant decrease in total and LDL cholesterol in the vitamin D group compared with the placebo group, but as there was also a decrease in HDL cholesterol, the change in the total/HDL cholesterol ratio did not differ significantly. Only analyzing subjects with 25(OH)D <50 nmol/L did not change the results. CONCLUSIONSThis study shows that vitamin D supplementation does not improve glycemic indices, blood pressure, or lipid status in subjects with IFG and/or IGT.The number of people with type 2 diabetes has doubled in the past 30 years, and it is estimated that .360 million people worldwide have type 2 diabetes (1). Type 2 diabetes is associated not only with obesity but also with hypertension and hyperlipidemia and, subsequently, cardiovascular disease (2). Thus, the World Health Organization projects that diabetes will be the seventh leading cause of death in 2030 (3).Type 2 diabetes develops through a prediabetic stage with impaired fasting glucose (IFG) and/or impaired glucose tolerance (IGT) (4). Intervention in the prediabetic stage with changes in lifestyle and/or with medications may prevent progression to type 2 diabetes, as has been demonstrated in several clinical trials (5-7). Bariatric surgery resulting in weight loss may also prevent the development of type 2
Objective: To study whether serum parathyroid hormone (PTH) and serum calcium are associated with body mass index (BMI), and their predicting role in obesity. Design: Population based, cross-sectional study. Methods:In 2001 a population-based health survey was held in Tromsø, North Norway. Questionnaires on medical history and life-style factors were completed and anthropometric data were collected. Calcium and vitamin D intakes and a physical activity score were calculated. Serum calcium and PTH were measured in a subset of 3447 men and 4507 women. Pearson correlation and linear regression were used to evaluate associations between BMI, PTH and serum calcium, and logistic regression was used to test PTH and serum calcium as predictors of obesity and to calculate odds ratio. Relative risk was calculated using frequency tables. Results: For serum calcium and PTH there was a significant positive relation to BMI in both genders (P , 0.001), which to our knowledge has not previously been reported on the basis of a large epidemiological study. Age, low calcium and vitamin D intakes were explanatory variables for serum PTH. The highest quartile of serum PTH (.4.20 pmol/l) was a significant predictor for obesity (P , 0.001) in both genders, adjusted for age, physical activity and serum calcium. Obesity rates were higher in those with PTH levels in the highest quartile compared with those in the lower quartiles, which resulted in a relative risk of 1.40 (95% confidence interval (C.I.) 1.20 -1.60) for men and 1.48 (95% C.I. 1.31 -1.67) for women. Conclusions: Serum PTH, adjusted for age, physical activity and serum calcium, is positively associated with BMI in both sexes, and serum PTH is an independent predictor of obesity in our statistical model.
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