Since 2000, there has been an increase in research on possible health benefits of vitamin D. However, a 2011 Institute of Medicine (IOM; now the National Academy of Medicine) report concluded that vitamin D was beneficial for bone health but evidence was insufficient for extraskeletal health. 1 Several large-scale trials are ongoing to evaluate the effect of vitamin D supplementation on extraskeletal outcomes. 2 The IOM report noted possible harm (eg, hypercalcemia, soft tissue or vascular calcification) for intakes above the tolerable upper limit, which is the highest level of intake likely to pose no risk of adverse effects for most adults. 1 The recommended dietary allowance for vitamin D is 600 IU/d for adults 70 years or younger and 800 IU/d for those older than 70 years. The tolerable upper limit is 4000 IU/d; beyond this level risk of toxic effects increases. 1 Multivita-mins typically contain about 400 IU/d; consumption of 1000 IU or more daily likely indicates intentionally seeking supplemental vitamin D.We assessed trends in daily supplemental vitamin D intake of 1000 IU or more and 4000 IU or more from 1999 through 2014.

IMPORTANCEThe term prediabetes is used to identify individuals at increased risk for diabetes. However, the natural history of prediabetes in older age is not well characterized.OBJECTIVES To compare different prediabetes definitions and characterize the risks of prediabetes and diabetes among older adults in a community-based setting. DESIGN, SETTING, AND PARTICIPANTS In this prospective cohort analysis of 3412 older adults without diabetes from the Atherosclerosis Risk in Communities Study (baseline, 2011-2013), participants were contacted semiannually through December 31, 2017, and attended a follow-up visit between January 1, 2016, and December 31, 2017 (median [range] follow-up, 5.0 [0.1-6.5] years). EXPOSURES Prediabetes defined by a glycated hemoglobin (HbA 1c ) level of 5.7% to 6.4%, impaired fasting glucose (IFG) level (FG level of 100-125 mg/dL), either, or both. MAIN OUTCOMES AND MEASURES Incident total diabetes (physician diagnosis, glucose-lowering medication use, HbA 1c level Ն6.5%, or FG level Ն126 mg/dL). RESULTS A total of 3412 participants without diabetes (mean [SD] age, 75.6 [5.2] years; 2040 [60%] female; and 572 [17%] Black) attended visit 5 (2011-2013, baseline). Of the 3412 participants at baseline, a total of 2497 participants attended the follow-up visit or died. During the 6.5-year follow-up period, there were 156 incident total diabetes cases (118 diagnosed) and 434 deaths. A total of 1490 participants (44%) had HbA 1c levels of 5.7% to 6.4%, 1996 (59%) had IFG, 2482 (73%) met the HbA 1c or IFG criteria, and 1004 (29%) met both the HbA 1c and IFG criteria. Among participants with HbA 1c levels of 5.7% to 6.4% at baseline, 97 (9%) progressed to diabetes, 148 (13%) regressed to normoglycemia (HbA 1c , <5.7%), and 207 (19%) died. Of those with IFG at baseline, 112 (8%) progressed to diabetes, 647 (44%) regressed to normoglycemia (FG, <100 mg/dL), and 236 (16%) died. Of those with baseline HbA 1c levels less than 5.7%, 239 (17%) progressed to HbA 1c levels of 5.7% to 6.4% and 41 (3%) developed diabetes. Of those with baseline FG levels less than 100 mg/dL, 80 (8%) progressed to IFG (FG, 100-125 mg/dL) and 26 (3%) developed diabetes. CONCLUSIONS AND RELEVANCEIn this community-based cohort study of older adults, the prevalence of prediabetes was high; however, during the study period, regression to normoglycemia or death was more frequent than progression to diabetes. These findings suggest that prediabetes may not be a robust diagnostic entity in older age.

Background: Elevated serum calcium has been associated with a variety of metabolic abnormalities and may be associated with a greater risk of diabetes. Objective: The purpose of this study was to test the hypothesis that serum calcium concentration is positively and independently associated with the incidence of diabetes and to evaluate the association of calcium-sensing receptor (CaSR) gene single nucleotide polymorphism (SNP) rs1801725 with incident diabetes. Design: Atherosclerosis Risk in Communities study participants free of diabetes at baseline (n = 12,800; mean age: 53.9 y; 22.6% black) were studied for incident diabetes. Serum calcium was measured at baseline and corrected for serum albumin. Diabetes was defined by use of glucose concentrations, self-report, or medication use. Cox proportional hazards regression was used. Results: During a mean 8.8 y of follow-up, 1516 cases of diabetes were reported. Participants in the highest compared with lowest calcium quintile were at greater risk of incident diabetes after adjustment for demographic and lifestyle factors [HR (95% CI): 1.34 (1.14, 1.57); P-trend across quintiles ,0.0001] and with further adjustment for waist circumference and body mass index [1.26 (1.07, 1.48); P-trend = 0.004]. Additional adjustment for biomarkers on the metabolic pathway (e.g., 25-hydroxyvitamin D, parathyroid hormone, phosphorus) had little impact. The calcium-diabetes association was statistically significant in blacks [1.48 (1.11, 1.98); P-trend = 0.002] but not whites [1.17 (0.96, 1.43); P-trend = 0.17] after adjustment for adiposity. In whites, CaSR gene SNP rs1801725 was associated with serum calcium but not with risk of diabetes. Conclusions: Consistent with 3 previous cohort studies, elevated serum calcium was found to be associated with a greater risk of type 2 diabetes. Further research is needed to understand the role, if any, that calcium plays in the pathogenesis of diabetes.Am J Clin Nutr 2016;104:1023-9.

Background: The prevalence of subclinical atrial fibrillation (AF) in the elderly general population is unclear. We sought to define the prevalence of subclinical AF in a community-based elderly population and to characterize subclinical AF and the incremental diagnostic yield of 4 versus 2 weeks of continuous ECG monitoring. Methods: We conducted a cross-sectional analysis within the community-based multicenter observational ARIC study (Atherosclerosis Risk in Communities) using visit 6 (2016–2017) data. The 2616 ARIC study participants who wore a leadless, ambulatory ECG monitor (Zio XT Patch) for up to 2 weeks were aged 79±5 years, 42% men, and 26% black. In a subset, 386 participants without clinically recognized AF wore the monitor twice, each time for up to 2 weeks. We characterized the prevalence of subclinical AF (ie, AF detected on the Zio XT Patch without clinically recognized AF) over 2 weeks of monitoring and the diagnostic yield of 4 versus 2 weeks of monitoring. Results: The prevalence of subclinical AF was 2.5%; the prevalence of subclinical AF was 3.3% among white men, 2.5% among white women, 2.1% among black men, and 1.6% among black women. Subclinical AF was mostly intermittent (75%). Among those with intermittent subclinical AF, 91% had AF burden ≤10% during the monitoring period. In a subset of 386 participants without clinical AF, 78% more subclinical AF was detected by 4 weeks versus 2 weeks of ECG monitoring. Conclusions: In our study, the prevalence of subclinical AF was lower than previously reported and monitoring beyond 2 weeks provided substantial incremental diagnostic yield. Future studies should focus on individuals with higher risk to increase diagnostic yield and consider continuous monitoring duration longer than 2 weeks.