Mitochondrial DNA copy number and diabetes: the Atherosclerosis Risk in Communities (ARIC) study

INTRODUCTION

Mitochondrial DNA copy number (mtDNA-CN) is a measure of mitochondrial dysfunction and is associated with diabetes in experimental models. To explore the temporality of mitochondrial dysfunction and diabetes, we estimated the prevalent and incident association of mtDNA-CN and diabetes.

RESEARCH DESIGN AND METHODS

We assessed the associations of mtDNA-CN measured from buffy coat with prevalent and incident diabetes, stratified by race, in 8954 white and 2444 black participants in the Atherosclerosis Risk in Communities (ARIC) study, an observational cohort study. Follow-up for incident analyses was complete through visit 6, 2016.

RESULTS

Mean age at mtDNA-CN measurement was 57 years and 59% were female. Prevalence of diabetes at time of mtDNA-CN measurement was higher in blacks (563/2444, 23%) than whites (855/8954, 10%). The fully adjusted odds of prevalent diabetes for the 10th vs 90th percentile of mtDNA-CN was 1.05 (95% CI 0.74 to 1.49) among black and 1.49 (95% CI 1.20 to 1.85) among white participants. Over a median follow-up time of 19 years (Q1, Q3: 11, 24 years), we observed 617 incident diabetes cases among 1744 black and 2121 cases among 7713 white participants free of diabetes at baseline. The fully adjusted hazard of incident diabetes for the 10th vs 90th percentile of mtDNA-CN was 1.07 (95% CI 0.84 to 1.38) among black and 0.97 (95% CI 0.86 to 1.10) among white participants.

CONCLUSIONS

Lower mtDNA-CN in buffy coat was associated with prevalent diabetes in white but not black ARIC participants. Lower mtDNA-CN was not associated with incident diabetes over 20 years of follow-up in whites or blacks.

The Relationship of Lean Body Mass With Aging to the Development of Diabetes

CONTEXT

Older adults have the greatest burden of diabetes; however, the contribution of age-related muscle loss to its development remains unclear.

OBJECTIVE

We assessed the relationship of lean body mass with aging to incident diabetes in community-dwelling adults.

DESIGN AND SETTING

We studied participants in the Baltimore Longitudinal Study of Aging with median follow-up of 7 years (range 1-16). Cox proportional hazard models with age as the time scale were used. Time-dependent lean body mass measures were updated at each follow-up visit available.

PARTICIPANTS

Participants included 871 men and 984 women without diabetes who had  ≥ 1 assessment of body composition using dual x-ray absorptiometry.

MAIN OUTCOMES

Incident diabetes, defined as self-reported history and use of glucose-lowering medications; or fasting plasma glucose ≥ 126 mg/dL and 2-hour oral glucose tolerance test glucose ≥ 200 mg/dL either at the same visit or 2 consecutive visits.

RESULTS

The baseline mean [standard deviation] age was 58.9  [17.3] years. Men and women with a higher percentage of total lean body mass had lower fasting and 2-hour glucose levels, and less prediabetes (all P < 0.01). Among men, comparing highest versus lowest quartiles, percentage of total lean body mass (hazard ratio [HR],  0.46; 95% confidence interval, 0.22-0.97), percentage leg lean mass (HR, 0.38; 0.15-0.96), and lean-to-fat mass ratio (HR, 0.39; 0.17-0.89) were inversely associated with incident diabetes after accounting for race and attenuated after adjustment for height and weight. Conversely, absolute total lean body mass was positively associated with incident diabetes among women, with similar trends in men. No associations were observed with muscle strength or quality.

CONCLUSIONS

Relatively lower lean body mass with aging is associated with incident diabetes in men and partially related to anthropometrics, but not so in women.

Plasma Soluble αKlotho, Serum Fibroblast Growth Factor 23, and Mobility Disability in Community-Dwelling Older Adults

CONTEXT

αKlotho is a hormone and co-receptor for fibroblast growth factor 23 (FGF23), a hormone that downregulates active vitamin D synthesis and promotes phosphate excretion. Low αKlotho and high FGF23 occur in chronic kidney disease (CKD).

OBJECTIVE

We aimed to assess the relationships of αKlotho and FGF23 with mobility disability in community-dwelling older adults.

DESIGN AND SETTING

We estimated associations of plasma-soluble αKlotho and serum FGF23 concentrations with mobility disability over 6 years. Additional analyses was stratified by CKD.

PARTICIPANTS

Participants included 2751 adults (25.0% with CKD), aged 71 to 80 years, from the 1998 to 1999 Health, Aging, and Body Composition Study visit.

MAIN OUTCOME MEASURES

Walking disability and stair climb disability were defined as self-reported "a lot of difficulty" or an inability to walk a quarter mile and climb 10 stairs, respectively.

RESULTS

Median (interquartile range [IQR]) serum FGF23 and plasma soluble αKlotho concentrations were 46.6 (36.7, 60.2) pg/mL and 630.4 (478.4, 816.0) pg/mL, respectively. After adjustment, higher αKlotho concentrations were associated with lower walking disability rates (Rate Ratio [RR] highest vs. lowest tertile = 0.74; 95% confidence interval l [CI] = 0.62, 0.89; P = 0.003). Higher FGF23 concentrations were associated with higher walking disability rates (RR highest vs. lowest tertile = 1.24; 95%CI = 1.03, 1.50; P = 0.005). Overall, higher αKlotho combined with lower FGF23 was associated with the lowest walking disability rates (P for interaction = 0.023). Stair climb disability findings were inconsistent. No interactions with CKD were statistically significant (P for interaction > 0.10).

CONCLUSIONS

Higher plasma soluble αKlotho and lower serum FGF23 concentrations were associated with lower walking disability rates in community-dwelling older adults, particularly those without CKD.

Glycemic Markers and Subclinical Cardiovascular Disease: The Jackson Heart Study

Background We investigated the associations of glycemic markers (HbA_1C [hemoglobin A_1C], fasting plasma glucose, and insulin resistance-homeostasis model assessment of insulin resistance) with subclinical cardiovascular disease (CVD) among blacks. Methods We included 4303 community-dwelling blacks (64% women; mean age, 54.5 years) without prevalent CVD. Subclinical CVD was defined as ≥1 of the following: any coronary artery calcification (CAC), elevated carotid intima-media thickness (cIMT), left ventricular (LV) hypertrophy, LV ejection fraction <50%, and peripheral artery disease (ankle-brachial index, <0.90). Estimates of cross-sectional associations of glycemic markers (fasting plasma glucose, HbA_1C, and homeostasis model assessment of insulin resistance) with subclinical CVD measures were adjusted for traditional CVD risk factors. Results Each 1% increment in HbA_1C was associated with higher odds of CAC, abnormal cIMT, and subclinical CVD (all P <0.001). Adjusted mean values of LV mass (LVM), LVM index, relative wall thickness, CAC, and cIMT were increasingly abnormal with worsening HbA_1C categories (all P<0.05). Each 10-mg/dL increase in fasting plasma glucose was associated with higher odds of LV hypertrophy, CAC, abnormal cIMT, and subclinical CVD (all P <0.005). Adjusted mean values of LVM, LVM index, relative wall thickness, CAC, ankle-brachial index, and cIMT were more abnormal across categories of worsening fasting plasma glucose (all P <0.05). Each unit increment in log-transformed homeostasis model assessment of insulin resistance conferred a higher odd of having LV hypertrophy ( P<0.01). Across quartiles of homeostasis model assessment of insulin resistance, we observed progressively abnormal adjusted mean values of LVM, LVM index, relative wall thickness, and ankle-brachial index (all P <0.01). Conclusions Among blacks, glycemic markers were differentially associated with various measures of subclinical CVD.

Heart Failure End Points in Cardiovascular Outcome Trials of Sodium Glucose Cotransporter 2 Inhibitors in Patients With Type 2 Diabetes Mellitus: A Critical Evaluation of Clinical and Regulatory Issues

Following regulatory guidance set forth in 2008 by the US Food and Drug Administration for new drugs for type 2 diabetes mellitus, many large randomized, controlled trials have been conducted with the primary goal of assessing the safety of antihyperglycemic medications on the primary end point of major adverse cardiovascular events, defined as cardiovascular death, nonfatal myocardial infarction, or nonfatal stroke. Heart failure (HF) was not specifically mentioned in the US Food and Drug Administration guidance and therefore it was not a focus of these studies when planned. Several trials subsequently showed the impact of antihyperglycemic drugs on HF outcomes, which were not originally specified as the primary end point of the trials. The most impressive finding has been the substantial and consistent risk reduction in HF hospitalization seen across 4 trials of sodium glucose cotransporter 2 inhibitors. However, to date, these results have not led to regulatory approval of any of these drugs for a HF indication or a recommendation for use by US HF guidelines. It is therefore important to explore to what extent persuasive treatment effects on nonprimary end points can be used to support regulatory claims and guideline recommendations. This topic was discussed by researchers, clinicians, industry sponsors, regulators, and representatives from professional societies, who convened on the US Food and Drug Administration campus on March 6, 2019. This report summarizes these discussions and the key takeaway messages from this meeting.

Relationship of Physical Frailty to Phosphocreatine Recovery in Muscle after Mild Exercise Stress in the Oldest-Old Women

BACKGROUND

Physical frailty is a clinical syndrome associated with aging and manifesting as slowness, weakness, reduced physical activity, weight loss, and/or exhaustion. Frail older adults often report that their major problem is "low energy", and there is indirect evidence to support the hypothesis that frailty is a syndrome of dysregulated energetics. We hypothesized that altered cellular energy production underlies compromised response to stressors in the frail.

METHODS

We conducted a pilot study to assess muscle energetics in response to a mild isometric exercise challenge in women (n=30) ages 84-93 years. The frailty status was assessed by a validated physical frailty instrument. Localized phosphorus (P31) magnetic resonance spectroscopy with a 1.5T magnet was used to assess the kinetics of Phosphocreatine recovery in the tibialis anterior muscle following maximal isometric contraction for 30 seconds.

RESULTS

Phosphocreatine recovery following exertion, age-adjusted, was slowest in the frail group (mean=189 sec; 95%CI: 150,228) compared to pre-frail (mean=152 sec; 95%CI: 107,197) and nonfrail subjects (mean=132 sec; 95%CI: 40,224). The pre-frail and frail groups had 20 sec (95%CI: -49,89) and 57 sec (95%CI: -31,147) slower phosphocreatine recovery, respectively, than the non-frail. This response was paralleled by dysregulation in glucose recovery in response to oral glucose tolerance test in women from the same study population.

CONCLUSIONS

Impaired muscle energetics and energy metabolism might be implicated in the physical frailty syndrome.

Aspirin for Primary Prevention of Cardiovascular Disease in Diabetes: a Review of the Evidence

PURPOSE OF REVIEW

People with diabetes are at a higher risk of atherosclerotic cardiovascular disease (ASCVD) compared with those without diabetes. Though aspirin has been shown to have an overall net clinical benefit when used for secondary prevention of ASCVD in people with and without diabetes, the evidence for primary prevention, especially in those with diabetes, remains inconsistent. In this article, we review the latest studies examining the risks and benefits of aspirin use for primary prevention of ASCVD in adults with diabetes, discuss key aspects in assessing the risk-benefit ratio of aspirin use for primary prevention of ASCVD, and summarize current guidelines from professional societies on aspirin use for primary prevention in adults with diabetes.

RECENT FINDINGS

In the general population, past studies have shown no difference in the beneficial effect of aspirin for primary cardiovascular disease prevention by diabetes status. However, several randomized controlled studies and meta-analyses in adults with diabetes have shown lack of net clinical benefit of aspirin use for primary prevention of ASCVD. The recent ASCEND trial documented cardiovascular benefit of aspirin for primary prevention in adults with diabetes but suggested that the increased risk of bleeding may outweigh the cardiovascular benefit. The decision to initiate aspirin for primary prevention of ASCVD must be considered carefully on an individual basis to balance the cardiovascular benefit and bleeding risk in all patients, especially those with diabetes. A multifactorial approach that focuses on managing ASCVD risk factors such as hypertension, dyslipidemia, dysglycemia, and smoking is recommended in all patients. More research is needed to identify subgroups of people with diabetes who are more likely to benefit from aspirin use for primary prevention of ASCVD and develop better antithrombotic strategies that shift the risk-benefit balance toward an overall net clinical benefit.

Regression From Prediabetes to Normal Glucose Regulation and Prevalence of Microvascular Disease in the Diabetes Prevention Program Outcomes Study (DPPOS)

OBJECTIVE

Regression from prediabetes to normal glucose regulation (NGR) was associated with reduced incidence of diabetes by 56% over 10 years in participants in the Diabetes Prevention Program Outcomes Study (DPPOS). In an observational analysis, we examined whether regression to NGR also reduced risk for microvascular disease (MVD).

RESEARCH DESIGN AND METHODS

Generalized estimating equations were used to examine the prevalence of aggregate MVD at DPPOS year 11 in people who regressed to NGR at least once (vs. never) during the Diabetes Prevention Program (DPP). Logistic regression assessed the relationship of NGR with retinopathy, nephropathy, and neuropathy, individually. Generalized additive models fit smoothing splines to describe the relationship between average A1C during follow-up and MVD (and its subtypes) at the end of follow-up.

RESULTS

Regression to NGR was associated with lower prevalence of aggregate MVD in models adjusted for age, sex, race/ethnicity, baseline A1C, and treatment arm (odds ratio [OR] 0.78, 95% CI 0.65-0.78, P = 0.011). However, this association was lost in models that included average A1C during follow-up (OR 0.95, 95% CI 0.78-1.16, P = 0.63) or diabetes status at the end of follow-up (OR 0.92, 95% CI 0.75-1.12, P = 0.40). Similar results were observed in examination of the association between regression to NGR and prevalence of nephropathy and retinopathy, individually. Risk for aggregate MVD, nephropathy, and retinopathy increased across the A1C range.

CONCLUSIONS

Regression to NGR is associated with a lower prevalence of aggregate MVD, nephropathy, and retinopathy, primarily due to lower glycemic exposure over time. Differential risk for the MVD subtypes begins in the prediabetes A1C range.

Primary Prevention of ASCVD and T2DM in Patients at Metabolic Risk: An Endocrine Society* Clinical Practice Guideline

OBJECTIVE

To develop clinical practice guidelines for the primary prevention of atherosclerotic cardiovascular disease (ASCVD) and type 2 diabetes mellitus (T2DM) in individuals at metabolic risk for developing these conditions.

CONCLUSIONS

Health care providers should incorporate regular screening and identification of individuals at metabolic risk (at higher risk for ASCVD and T2DM) with measurement of blood pressure, waist circumference, fasting lipid profile, and blood glucose. Individuals identified at metabolic risk should undergo 10-year global risk assessment for ASCVD or coronary heart disease to determine targets of therapy for reduction of apolipoprotein B-containing lipoproteins. Hypertension should be treated to targets outlined in this guideline. Individuals with prediabetes should be tested at least annually for progression to diabetes and referred to intensive diet and physical activity behavioral counseling programs. For the primary prevention of ASCVD and T2DM, the Writing Committee recommends lifestyle management be the first priority. Behavioral programs should include a heart-healthy dietary pattern and sodium restriction, as well as an active lifestyle with daily walking, limited sedentary time, and a structured program of physical activity, if appropriate. Individuals with excess weight should aim for loss of ≥5% of initial body weight in the first year. Behavior changes should be supported by a comprehensive program led by trained interventionists and reinforced by primary care providers. Pharmacological and medical therapy can be used in addition to lifestyle modification when recommended goals are not achieved.

Plasma Klotho and Frailty in Older Adults: Findings From the InCHIANTI Study

BACKGROUND

The hormone klotho, encoded by the gene klotho, is primarily expressed in the kidney and choroid plexus of the brain. Higher klotho concentrations have been linked to better physical performance; however, it is unknown whether klotho relates to frailty status in older adults.

METHODS

Plasma klotho was measured in 774 participants aged ≥65 years enrolled in InCHIANTI, a prospective cohort study comprising Italian adults. Frailty status was assessed at 3 and 6 years after enrollment. Frailty was defined as presence of at least three out of five criteria of unintentional weight loss, exhaustion, sedentariness, muscle weakness, and slow walking speed; prefrailty was defined as presence of one or two criteria; and robustness was defined as zero criteria. We assessed whether plasma klotho concentrations measured at the 3-year visit related to frailty.

RESULTS

Each additional natural logarithm of klotho (pg/mL) was associated with lower odds of frailty versus robustness after adjustment for covariates (odds ratio [OR] 0.46; 95% confidence interval 0.21, 0.98; p-value = .045). Higher klotho was particularly associated with lower odds of exhaustion (OR 0.57; 95% CI 0.36, 0.89; p-value = .014). Participants with higher klotho also had lower estimated odds of weight loss and weakness, but these findings were not statistically significant.

CONCLUSIONS

Higher plasma klotho concentrations were associated with lower likelihoods of frailty and particularly exhaustion. Future studies should investigate modifiable mechanisms through which klotho may affect the frailty syndrome.

Body composition changes in diabetes and aging

Aging is associated with changes in body composition, including both fat gain and muscle loss beginning in middle age, and is associated with increased risk of type 2 diabetes. Moreover, changes in fat distribution take place in adults as they age and may contribute to the increased risk of type 2 diabetes. Recent literature has shown differences in the age-related changes in body composition by diabetes status suggesting that some of these changes might not only be a risk factor of the development of diabetes but could also be a consequence of the disease. In this article, we review the current evidence on body composition changes that take place in adults after the diagnosis of type 2 diabetes and compare them to those observed in adults without diabetes as they age. We also review the effect of various lifestyle, pharmacological, and surgical treatments that lower blood glucose on body composition in adults with type 2 diabetes.

Long-Term Weight Loss With Metformin or Lifestyle Intervention in the Diabetes Prevention Program Outcomes Study

BACKGROUND

Identifying reliable predictors of long-term weight loss (LTWL) could lead to improved weight management.

OBJECTIVE

To identify some predictors of LTWL.

DESIGN

The DPP (Diabetes Prevention Program) was a randomized controlled trial that compared weight loss with metformin, intensive lifestyle intervention (ILS), or placebo. Its Outcomes Study (DPPOS) observed patients after the masked treatment phase ended. (ClinicalTrials.gov: NCT00004992 and NCT00038727).

SETTING

27 DPP and DPPOS clinics.

PARTICIPANTS

Of the 3234 randomly assigned participants, 1066 lost at least 5% of baseline weight in the first year and were followed for 15 years.

MEASUREMENTS

Treatment assignment, personal characteristics, and weight.

RESULTS

After 1 year, 289 (28.5%) participants in the metformin group, 640 (62.6%) in the ILS group, and 137 (13.4%) in the placebo group had lost at least 5% of their weight. After the masked treatment phase ended, the mean weight loss relative to baseline that was maintained between years 6 and 15 was 6.2% (95% CI, 5.2% to 7.2%) in the metformin group, 3.7% (CI, 3.1% to 4.4%) in the ILS group, and 2.8% (CI, 1.3% to 4.4%) in the placebo group. Independent predictors of LTWL included greater weight loss in the first year in all groups, older age and continued metformin use in the metformin group, older age and absence of either diabetes or a family history of diabetes in the ILS group, and higher fasting plasma glucose levels at baseline in the placebo group.

LIMITATION

Post hoc analysis; examination of nonrandomized subsets of randomized groups after year 1.

CONCLUSION

Among persons with weight loss of at least 5% after 1 year, those originally randomly assigned to metformin had the greatest loss during years 6 to 15. Older age and the amount of weight initially lost were the most consistent predictors of LTWL maintenance.

PRIMARY FUNDING SOURCE

National Institutes of Health.

The association of morning serum cortisol with glucose metabolism and diabetes: The Jackson Heart Study

BACKGROUND

Serum cortisol levels have been associated with type 2 diabetes (T2D). However, the role of cortisol in glycemia and T2D is not fully elucidated among African Americans (AAs). We hypothesized that among AAs morning serum cortisol would be positively associated with glycemic measures and prevalent T2D.

METHODS

We examined the cross-sectional association of baseline morning serum cortisol with fasting plasma glucose (FPG), hemoglobin A1c (HbA1c), homeostasis model assessment of insulin resistance (HOMA-IR), β-cell function (HOMA-β), and prevalent T2D in the Jackson Heart Study. Linear regression models were used to examine the association of log-transformed cortisol with glycemic traits, stratified by T2D status. Logistic regression was used to examine the association of log-transformed cortisol with prevalent T2D. Models were adjusted for age, sex, education, occupation, systolic blood pressure, waist circumference, physical activity, smoking, beta-blocker/hormone replacement medications and cortisol collection time.

RESULTS

Among 4,206 AAs (mean age 55 ± 13 years, 64% female), 19% had prevalent T2D. A 100% increase in cortisol among participants without diabetes was associated with 2.7 mg/dL (95% CI: 2.0, 3.3) higher FPG and a 10.0% (95% CI: -14.0, -6.0) lower HOMA-β with no significant association with HbA1c or HOMA-IR. In participants with diabetes, a 100% increase in cortisol was associated with a 23.6 mg/dL (95% CI: 13.6, 33.7) higher FPG and a 0.6% (95% CI: 0.3, 0.9) higher HbA1c. Among all participants, quartile 4 vs. 1 of cortisol was associated with a 1.26-fold (95% CI: 1.75, 2.91) higher odds of prevalent T2D.

CONCLUSION

Higher morning serum cortisol was associated with higher FPG and lower β-cell function among participants without T2D and higher FPG and HbA1c in participants with diabetes. Among all participants, higher cortisol was associated with higher odds of T2D. These findings support a role for morning serum cortisol in glucose metabolism among AAs.

Sex Hormones and Measures of Kidney Function in the Diabetes Prevention Program Outcomes Study

CONTEXT

Despite sex differences in chronic kidney disease (CKD) onset and progression, it is unclear whether endogenous sex hormones are associated with kidney function in persons without CKD.

DESIGN AND METHODS

We conducted a secondary analysis of the Diabetes Prevention Program (DPP) and its follow-up observational study, the DPP Outcomes Study, over 11 years. Participants included overweight and glucose-intolerant men (n = 889) and pre- and postmenopausal women (n = 1281) not using exogenous sex hormones and whose urine albumin-to-creatinine ratio (ACR) was <30 mg/g and normal estimated glomerular filtration ratio (eGFR) was ≥60 mL/min/1.73 m2 at randomization. We examined the association between sex hormone levels and incidence of low eGFR and/or ACR ≥30 mg/g on at least one measurement.

RESULTS

At randomization, the mean (SD) eGFR was 94 (15) mL/min/1.73 m2; the median ACR (interquartile range) was 4.5 (3.3 to 7.6) mg/g. During follow-up, 187 men (24.6%) and 263 women (24.2%) had incident albuminuria and 136 men (17.9%) and 123 women (11.3%) had incident low eGFR. Among men, higher baseline sex hormone-binding globulin (SHBG) level was associated with reduced low eGFR risk (hazard ratio per SD, 0.80; 95% CI, 0.57 to 0.90) in adjusted analyses. No significant associations were observed among women. There were significant interactions between sex steroid levels and low eGFR by randomization arm.

CONCLUSION

Sex steroids were not associated with development of low eGFR or albuminuria. Among men, higher SHBG level was associated with reduced risk of low eGFR on at least one measurement.

Leveraging linkage evidence to identify low-frequency and rare variants on 16p13 associated with blood pressure using TOPMed whole genome sequencing data

In this study, we investigated low-frequency and rare variants associated with blood pressure (BP) by focusing on a linkage region on chromosome 16p13. We used whole genome sequencing (WGS) data obtained through the NHLBI Trans-Omics for Precision Medicine (TOPMed) program on 395 Cleveland Family Study (CFS) European Americans (CFS-EA). By analyzing functional coding variants and non-coding rare variants with CADD score > 10 residing within the chromosomal region in families with linkage evidence, we observed 25 genes with nominal statistical evidence (burden or SKAT p < 0.05). One of the genes is RBFOX1, an evolutionarily conserved RNA-binding protein that regulates tissue-specific alternative splicing that we previously reported to be associated with BP using exome array data in CFS. After follow-up analysis of the 25 genes in ten independent TOPMed studies with individuals of European, African, and East Asian ancestry, and Hispanics (N = 29,988), we identified variants in SLX4 (p = 2.19 × 10-4) to be significantly associated with BP traits when accounting for multiple testing. We also replicated the associations previously reported for RBFOX1 (p = 0.007). Follow-up analysis with GTEx eQTL data shows SLX4 variants are associated with gene expression in coronary artery, multiple brain tissues, and right atrial appendage of the heart. Our study demonstrates that linkage analysis of family data can provide an efficient approach for detecting rare variants associated with complex traits in WGS data.

Diabetes and Platelet Response to Low-Dose Aspirin

CONTEXT

Previous studies have suggested less cardioprotective benefit of aspirin in adults with diabetes, raising concerns about "aspirin resistance" and potentially reduced effectiveness for prevention of cardiovascular disease (CVD).

OBJECTIVE

To examine differences in platelet response to aspirin by diabetes status.

DESIGN, SETTING, PARTICIPANTS

We examined platelet response before and after aspirin (81 mg/day for 14 days) in 2113 adults (175 with diabetes, 1,938 without diabetes), in the Genetic Study of Aspirin Responsiveness cohort, who had family history of early-onset CVD.

MAIN OUTCOME MEASURES

In vivo platelet activation (urinary thromboxane B2), in vitro platelet aggregation to agonists (arachidonic acid, adenosine diphosphate, collagen), and platelet function analyzer-100 closure time.

RESULTS

Although adults with diabetes had higher in vivo platelet activation before aspirin, the reduction in in vivo platelet activation after aspirin was similar in those with vs without diabetes. Likewise, the reduction in multiple in vitro platelet measures was similar after aspirin by diabetes status. In regression analyses adjusted for age, sex, race, BMI, smoking, platelet counts, and fibrinogen levels, in vivo platelet activation remained higher in adults with vs without diabetes after aspirin (P = 0.04), but this difference was attenuated after additional adjustment for preaspirin levels (P = 0.10). No differences by diabetes status were noted for any of the in vitro platelet measures after aspirin in fully adjusted models that also accounted for preaspirin levels.

CONCLUSIONS

In vitro platelet response to aspirin does not differ by diabetes status, suggesting no intrinsic differences in platelet response to aspirin. Instead, factors extrinsic to platelet function should be investigated to give further insights into aspirin use for primary prevention in diabetes.

Comparison of Measures of Adiposity and Cardiovascular Disease Risk Factors Among African American Adults: the Jackson Heart Study

Obesity, particularly central adiposity, is a well-established risk factor for cardiovascular disease (CVD). Waist circumference (WC) is measured in numerous epidemiologic studies as a relatively simple indicator of central adiposity. However, recently, investigators have considered a measure that takes height into consideration, waist-to-height ratio (WHtR) as a more sensitive predictor of CVD. A limited number of studies have examined the association between various measures of central adiposity and obesity with CVD, but there is a dearth of information on this topic focused specifically on African American adults. Given the high rates of cardiovascular disease and metabolic risk factors in this population, it is important to develop validated, easy-to-measure indicators of CVD risk for clinical use. Data from 4758 African American adults participating in the baseline visit of the Jackson Heart Study with available risk factor data were examined, with three measures of body habitus (body mass index (BMI), WC, and WHtR) and five CVD risk factors (HDL and LDL cholesterol, triglycerides, diabetes, and hypertension), the latter also categorized into multiple (2+) risk factors present. C-statistics for waist circumference (WC), BMI, and WHtR were computed and compared for each model to assess their discriminant abilities. WHtR was a stronger correlate of HDL cholesterol, triglycerides, diabetes, hypertension, and multiple risk factors compared to BMI, and was a stronger correlate of HDL cholesterol when compared to WC. These data indicate that, for African American adults, WHtR may be more appropriate measure to identify those at elevated risk for CVD.

Arterial Input Functions and Tissue Response Curves in Dynamic Glucose-Enhanced (DGE) Imaging: Comparison Between glucoCEST and Blood Glucose Sampling in Humans

Dynamic glucose-enhanced (DGE) imaging uses chemical exchange saturation transfer magnetic resonance imaging to retrieve information about the microcirculation using infusion of a natural sugar (D-glucose). However, this new approach is not yet well understood with respect to the dynamic tissue response. DGE time curves for arteries, normal brain tissue, and cerebrospinal fluid (CSF) were analyzed in healthy volunteers and compared with the time dependence of sampled venous plasma blood glucose levels. The arterial response curves (arterial input function [AIF]) compared reasonably well in shape with the time curves of the sampled glucose levels but could also differ substantially. The brain tissue response curves showed mainly negative responses with a peak intensity that was of the order of 10 times smaller than the AIF peak and a shape that was susceptible to both noise and partial volume effects with CSF, attributed to the low contrast-to-noise ratio. The CSF response curves showed a rather large and steady increase of the glucose uptake during the scan, due to the rapid uptake of D-glucose in CSF. Importantly, and contrary to gadolinium studies, the curves differed substantially among volunteers, which was interpreted to be caused by variations in insulin response. In conclusion, while AIFs and tissue response curves can be measured in DGE experiments, partial volume effects, low concentration of D-glucose in tissue, and osmolality effects between tissue and blood may prohibit quantification of normal tissue perfusion parameters. However, separation of tumor responses from normal tissue responses would most likely be feasible.

Rationale and design of the Study To Understand Fall Reduction and Vitamin D in You (STURDY): A randomized clinical trial of Vitamin D supplement doses for the prevention of falls in older adults

Prior evidence suggests that vitamin D supplementation may reduce fall risk, but existing data are inconsistent and insufficient to guide policy. We designed a two-stage Bayesian response-adaptive dose-finding and seamless confirmatory randomized trial of vitamin D supplementation to prevent falls. Up to 1200 community-dwelling persons, aged ≥70 years, of predominantly white and African-American race, with serum 25(OH)D concentrations of 10-29 ng/mL and at elevated fall risk, will be randomized to one of four vitamin D3 (cholecalciferol) supplement doses: 200 (control), 1000, 2000, or 4000 IU/day and treated for up to 2 years. Stage 1 is designed to identify the best of the non-control doses for fall prevention. If a best dose is selected, Stage 2 will start seamlessly, with enrollees assigned to control or the best dose in Stage 1 continuing on that dose unchanged, enrollees assigned to the two non-control, non-best doses in Stage 1 switched to the best dose, and new enrollees randomly assigned 1:1 to control or the best dose. In Stage 2, we will compare the control dose group to the best dose group to potentially confirm the efficacy of that dose for fall prevention. The primary outcome measure in both stages is time to first fall or death, whichever comes first. Falls are ascertained from calendars, scheduled interviews, or interim self-reports. Secondary outcome measures include time to each component of the composite primary outcome and gait speed. Additional outcomes include the Short Physical Performance Battery score, physical activity level (assessed by accelerometry), and frailty score.

CLINICAL TRIAL REGISTRATION

NCT02166333.

A Novel Extension to Fuzzy Connectivity for Body Composition Analysis: Applications in Thigh, Brain, and Whole Body Tissue Segmentation

Magnetic resonance imaging (MRI) is the non-invasive modality of choice for body tissue composition analysis due to its excellent soft-tissue contrast and lack of ionizing radiation. However, quantification of body composition requires an accurate segmentation of fat, muscle, and other tissues from MR images, which remains a challenging goal due to the intensity overlap between them. In this study, we propose a fully automated, data-driven image segmentation platform that addresses multiple difficulties in segmenting MR images such as varying inhomogeneity, non-standardness, and noise, while producing a high-quality definition of different tissues. In contrast to most approaches in the literature, we perform segmentation operation by combining three different MRI contrasts and a novel segmentation tool, which takes into account variability in the data. The proposed system, based on a novel affinity definition within the fuzzy connectivity image segmentation family, prevents the need for user intervention and reparametrization of the segmentation algorithms. In order to make the whole system fully automated, we adapt an affinity propagation clustering algorithm to roughly identify tissue regions and image background. We perform a thorough evaluation of the proposed algorithm's individual steps as well as comparison with several approaches from the literature for the main application of muscle/fat separation. Furthermore, whole-body tissue composition and brain tissue delineation were conducted to show the generalization ability of the proposed system. This new automated platform outperforms other state-of-the-art segmentation approaches both in accuracy and efficiency.

Highlights From the American Diabetes Association's 2017 Standards of Medical Care in Diabetes for Osteopathic Physicians

The American Diabetes Association (ADA) updates its Standards of Medical Care (SOMC) in Diabetes annually. These ADA standards make up a comprehensive document that serves as an excellent resource for clinical care. The current article comes from the ADA's Primary Care Advisory Group. This article highlights key aspects of the SOMC that are relevant to the day-to-day practice of osteopathic primary care physicians. It is not intended to replace the full SOMC but will refer to the master document for further explanation and evidence-based support.