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BACKGROUND Although vitamin D has been mechanistically linked to insulin secretion and sensitivity, it remains unclear whether low 25-hydroxyvitamin D levels confer an increased risk of impaired glucose metabolism. We evaluated the relationship between vitamin D insufficiency (25-hydroxyvitamin D < 20ng/mL) and abnormal hemoglobin A1c (A1c) (≥6.5%) in community-dwelling older persons and examined whether this relationship differed according to race. METHODS Participants were 2,193 persons of age 70-79 years at Year 1 (52% women; 37% black) in the Health, Aging, and Body Composition study who had clinic visits at Years 2 and 4. Logistic regression analyses, adjusted for potential confounders, were used to evaluate the association between vitamin D insufficiency and abnormal A1c 2 years later. Interaction of race and vitamin D insufficiency was tested. RESULTS A total of 665 (30%) and 301 (14%) of the participants had vitamin D insufficiency at Year 2 and abnormal A1c at Year 4, respectively. After controlling for demographics, other potential confounders, and diabetes status at Year 4 (n = 477 diabetics), we found that vitamin D insufficiency was associated with an increased likelihood of having abnormal A1c (odds ratio = 1.56; 95% CI: 1.03-2.37). We also found that this relationship persisted among the 1,765 participants without diabetes in Year 2 (odds ratio = 2.33; 95% CI: 1.00-5.40). Findings did not differ by race. CONCLUSIONS Vitamin D insufficiency was associated with abnormal A1c levels among black and white older persons independent of diabetes status. Future studies are needed to establish the temporal relationship between vitamin D and A1c in diverse samples of older persons.

To identify lifestyle related factors that may influence the prognosis of clinically localized prostate cancer we evaluated the relative impact of obesity and prostatic fatty acid concentrations at diagnosis on the risk of biochemical failure following radical prostatectomy.Height and weight were measured in 195 men scheduled for radical prostatectomy for clinically localized prostate cancer. Fatty acids were measured in nonmalignant prostate tissue collected at surgery. Biochemical failure was defined as detectable serum prostate specific antigen (0.1 ng/ml or greater). Cox proportional hazards models and logistic regression, respectively, were used to analyze the association of obesity (body mass index 30 kg/m2 or greater) and prostatic fatty acid concentrations with time to biochemical failure and the relative odds of biochemical failure at different time points after accounting for prostate specific antigen at diagnosis, surgical margin status, pathological stage, Gleason sum, patient age, race/ethnicity and other factors.During an average followup of 56 months the oleic-to-stearic acid ratio predicted the risk of biochemical failure (multivariate HR 1.50, 95% CI 1.17-1.91, p = 0.001 per 1 standard deviation increase). Obesity did not correlate with biochemical failure during the entire study period. However, obesity tended to be associated with biochemical failure within the first 2 years (multivariate OR 2.55, 95% CI 0.84-7.77, p = 0.10).The oleic-to-stearic acid ratio in the prostate predicts the risk of biochemical failure following radical prostatectomy for clinically localized prostate cancer. This observation and the tendency of obesity to be associated with biochemical failure during the first 2 years in our cohort suggest that lifestyle related factors influence the prognosis of clinically early stage prostate cancer.

OBJECTIVE Data relating vitamin D status with indices of glucose homeostasis as manifested by A1C in the U.S. adult population are few. RESEARCH DESIGN AND METHODS We examined the association between serum 25 hydroxyvitamin D [25(OH)D] and A1C levels in 9,773 adults (age ≥18 years old) participating in the 2003–2006 National Health and Nutrition Examination Survey. Multivariate linear regression analyzed the association after accounting for potential confounders. RESULTS Serum 25(OH)D levels were inversely associated with A1C levels in subjects age 35–74 years (P = 0.0045) and those who did not report a history of diabetes (P = 0.0282). CONCLUSIONS These findings support a mechanistic link between serum vitamin D concentrations, glucose homeostasis, and the evolution of diabetes in a large segment of the U.S. adult population. Screening people with elevated A1C levels for vitamin D insufficiency should be considered.

Objectives: To evaluate the independent and joint effects of C-reactive protein (CRP) and 25-OH vitamin D (25(OH)D) levels on mobility disability in older persons. Design: U.S. population-based cross-sectional study. Setting: National Health and Nutrition Examination Surveys (2001�2002). Participants: Individuals aged 50 and older (N = 1,826). Measurements: C-reactive protein (mg/dL), with high CRP defined as ?0.2 mg/dL, and 25(OH)D levels (ng/mL) operationalized as severe deficiency (

The scope of the diabetes epidemic stresses the critical need for primary prevention. The consumption of foods high in vitamin C has been associated with lower risk of diabetes. The aim of this study was to analyze the relation between vitamin C concentration and glycemic control index in a large sample of U.S. adults without a history of diabetes.We analyzed data collected from 7697 adult participants in the National Health and Nutrition Examination Survey (NHANES) 2003-2006 who did not report a history of diabetes. Multivariate linear regression analyzed the association of vitamin C and hemoglobin A1c (A1c) levels after accounting for potential confounders. We also conducted stratified analyses based on race/ethnicity, gender, age group, body mass index, and vitamin D status.Vitamin C concentrations were inversely associated with A1c (p = 0.0202). Stronger inverse associations were observed in subjects 18-44 years of age (p = 0.0017), as well as in female (p = 0.0035) and Mexican American (p = 0.0149) subgroups. Evidence of a significant interaction between vitamin C and vitamin D was noted in subjects aged 18-44 years and in females (p = 0.0073 and 0.0095 respectively), with the inverse association tending to be evident at lower levels of vitamin D.Vitamin C status may influence glycemic control. Investigators should be cognizant of the interaction of vitamins C and D and should take this into consideration in planning future studies.