Meghan M. Brashear

Accelerometer profiles of physical activity and inactivity in normal weight, overweight, and obese U.S. men and women

BackgroundThe 2005-2006 National Health and Nutrition Examination Survey (NHANES) is used to describe an accelerometer-derived physical activity/inactivity profile in normal weight (BMI < 25 kg/m2), overweight (25 ≤ BMI < 30 kg/m2), and obese (BMI ≥ 30 kg/m2) U.S. adults.MethodsWe computed physical activity volume indicators (activity counts/day, uncensored and censored steps/day), rate indicators (e.g., steps/minute), time indicators (employing NHANES activity counts/minute cut points to infer time in non-wear, sedentary, low, light, moderate, and vigorous intensities), the number of breaks in sedentary time (occasions when activity counts rose from < 100 activity/counts in one minute to ≥ 100 activity counts in the subsequent minute), achievement of public health guidelines, and classification by step-defined physical activity levels. Data were examined for evidence of consistent and significant gradients across BMI-defined categories.ResultsIn 2005-2006, U.S adults averaged 6,564 ± SE 107 censored steps/day, and after considering non-wear time, they spent approximately 56.8% of the rest of the waking day in sedentary time, 23.7% in low intensity, 16.7% in light intensity, 2.6% in moderate intensity, and 0.2% in vigorous intensity. Overall, approximately 3.2% of U.S. adults achieved public health guidelines. The normal weight category took 7,190 ± SE 157 steps/day, and spent 25.7 ± 0.9 minutes/day in moderate intensity and 7.3 ± 0.4 minutes/day in vigorous intensity physical activity. The corresponding numbers for the overweight category were 6,879 ± 140 steps/day, 25.3 ± 0.9 minutes/day, and 5.3 ± 0.5 minutes/day and for the obese category 5,784 ± 124 steps/day, 17.3 ± 0.7 minutes/day and 3.2 ± 0.4 minutes/day. Across BMI categories, increasing gradients and significant trends were apparent in males for sedentary time and decreasing gradients and significant trends were evident in time spent in light intensity, moderate intensity, and vigorous intensity. For females, there were only consistent gradients and significant trends apparent for decreasing amounts of time spent in moderate and vigorous intensity.ConclusionsSimple indicators of physical activity volume (i.e., steps/day) and time in light, moderate or vigorous intensity physical activity differ across BMI categories for both sexes, suggesting that these should continue to be targets for surveillance.

Template to improve glycemic control without reducing adiposity or dietary fat

Drugs that improve chronic hyperglycemia independently of insulin signaling or reduction of adiposity or dietary fat intake may be highly desirable. Ad36, a human adenovirus, promotes glucose uptake in vitro independently of adiposity or proximal insulin signaling. We tested the ability of Ad36 to improve glycemic control in vivo and determined if the natural Ad36 infection in humans is associated with better glycemic control. C57BL/6J mice fed a chow diet or made diabetic with a high-fat (HF) diet were mock infected or infected with Ad36 or adenovirus Ad2 as a control for infection. Postinfection (pi), systemic glycemic control, hepatic lipid content, and cell signaling in tissues pertinent to glucose metabolism were determined. Next, sera of 1,507 adults and children were screened for Ad36 antibodies as an indicator of past natural infection. In chow-fed mice, Ad36 significantly improved glycemic control for 12 wk pi. In HF-fed mice, Ad36 improved glycemic control and hepatic steatosis up to 20 wk pi. In adipose tissue (AT), skeletal muscle (SM), and liver, Ad36 upregulated distal insulin signaling without recruiting the proximal insulin signaling. Cell signaling suggested that Ad36 increases AT and SM glucose uptake and reduces hepatic glucose release. In humans, Ad36 infection predicted better glycemic control and lower hepatic lipid content independently of age, sex, or adiposity. We conclude that Ad36 offers a novel tool to understand the pathways to improve hyperglycemia and hepatic steatosis independently of proximal insulin signaling, and despite a HF diet. This metabolic engineering by Ad36 appears relevant to humans for developing more practical and effective antidiabetic approaches.

Prediabetes and Prehypertension in Healthy Adults Are Associated With Low Vitamin D Levels

OBJECTIVE To determine whether modest elevations of fasting serum glucose (FSG) and resting blood pressure (BP) in healthy adults are associated with differential serum vitamin D concentrations. RESEARCH DESIGN AND METHODS Disease-free adults in the National Health and Nutrition Examination Survey 2001–2006 were assessed. Prediabetes (PreDM) and prehypertension (PreHTN) were diagnosed using American Diabetes Association and Seventh Report of the Joint National Committee on Prevention, Detection, and Treatment of High Blood Pressure criteria: FSG 100–125 mg/dL and systolic BP 120–139 mmHg and/or diastolic BP 80–89 mmHg. Logistic regression was used to assess the effects of low vitamin D levels on the odds for PreDM and PreHTN in asymptomatic adults (n = 1,711). RESULTS The odds ratio for comorbid PreDM and PreHTN in Caucasian men (n = 898) and women (n = 813) was 2.41 (P < 0.0001) with vitamin D levels ≤76.3 versus >76.3 nmol/L after adjusting for age, sex, and BMI. CONCLUSIONS This study strengthens the plausibility that low serum vitamin D levels elevate the risk for early-stage diabetes (PreDM) and hypertension (PreHTN).

Exercise Training and Quality of Life in Individuals With Type 2 Diabetes A randomized controlled trial

OBJECTIVE To establish whether exercise improves quality of life (QOL) in individuals with type 2 diabetes and which exercise modalities are involved. RESEARCH DESIGN AND METHODS Health Benefits of Aerobic and Resistance Training in individuals with type 2 Diabetes (HART-D; n = 262) was a 9-month exercise study comparing the effects of aerobic training, resistance training, or a combination of resistance and aerobic training versus a nonexercise control group on hemoglobin A1c (HbA1c) in sedentary individuals with type 2 diabetes. This study is an ancillary analysis that examined changes in QOL after exercise training using the Short Form-36 Health Survey questionnaire compared across treatment groups and with U.S. national norms. RESULTS The ancillary sample (n = 173) had high baseline QOL compared with U.S. national norms. The QOL physical component subscale (PCS) and the general health (GH) subscale were improved by all three exercise training conditions compared with the control group condition (resistance: PCS, P = 0.005; GH, P = 0.003; aerobic: PCS, P = 0.001; GH, P = 0.024; combined: PCS, P = 0.015; GH, P = 0.024). The resistance training group had the most beneficial changes in bodily pain (P = 0.026), whereas physical functioning was most improved in the aerobic and combined condition groups (P = 0.025 and P = 0.03, respectively). The changes in the mental component score did not differ between the control group and any of the exercise groups (all P > 0.05). The combined training condition group had greater gains than the aerobic training condition group in the mental component score (P = 0.004), vitality (P = 0.031), and mental health (P = 0.008) and greater gains in vitality compared with the control group (P = 0.021). CONCLUSIONS Exercise improves QOL in individuals with type 2 diabetes. Combined aerobic/resistance exercise produces greater benefit in some QOL domains.

Reducing the Glycemic Index or Carbohydrate Content of Mixed Meals Reduces Postprandial Glycemia and Insulinemia Over the Entire Day but Does Not Affect Satiety

OBJECTIVE We evaluated the effects of mixed meals differing in glycemic index (GI) and carbohydrate content on postprandial serum glucose and insulin response, hunger, and satiety over the course of a 12-h day. RESEARCH DESIGN AND METHODS In this randomized crossover trial, 26 overweight or obese adults received four diets in random order (high GI, high carbohydrate [HGI-HC]; high GI, low carbohydrate [HGI-LC]; low GI, high carbohydrate [LGI-HC]; and low GI, low carbohydrate [LGI-LC]). All meals were prepared by a metabolic kitchen. Participants received breakfast, lunch, and dinner over the course of a 12-h day. Primary outcomes were postprandial serum glucose and insulin quantified as area under the curve. Hunger, fullness, and satiety were assessed by visual analog scale. RESULTS The HGI-LC, LGI-HC, and LGI-LC diets significantly reduced glucose and insulin area under the curve compared with the HGI-HC diet (P < 0.001 for all comparisons). There were no significant differences in ratings of hunger, fullness, or satiety between the different dietary treatments. CONCLUSIONS Reducing the GI or carbohydrate content of mixed meals reduces postprandial glycemia and insulinemia, and these changes can be sustained over the course of an entire day. However, there were no differences in subjective hunger and satiety ratings between the diets. These results demonstrate that maintaining a low GI or glycemic load diet is an effective method of controlling serum glucose and insulin levels.

Coexisting prehypertension and prediabetes in healthy adults: a pathway for accelerated cardiovascular events

High blood pressure and elevated serum glucose levels often precede adverse cardiovascular events. The cardiovascular risk in otherwise healthy US adults with prehypertension (PreHTN) and/or prediabetes (PreDM), although perceived to be high, is largely undocumented. Coexisting PreHTN and PreDM in healthy US adults, correlates with untoward alterations in the commonly recognized cardiometabolic risk factors. The study investigated disease-free US adults (n=4,561) from the NHANES database (1999–2006). PreHTN and PreDM were diagnosed using JNC 7 and American Diabetes Association criteria, respectively; PreHTN was defined as systolic blood pressure 120–139 and/or diastolic blood pressure 80–89 mm Hg, and PreDM was defined as fasting blood sugar 100–125 mg dl−1. The prevalence of coexisting PreHTN and PreDM (Co-PreHTN+PreDM) during the study period (1999–2006) was 11.2±0.6%. Prevalence increased with age, was higher in men, and was lowest in non-Hispanic Blacks. The mean systolic blood pressure was 126.0±0.5 mm Hg, diastolic blood pressure was 75.0±0.5 mm Hg and fasting blood sugar was106.3±0.3 mg dl−1. Compared to adults with normotension, normoglycemia, subjects with Co-PreHTN+PreDM displayed adversely altered cardiometabolic risk factors. Healthy men and women with Co-PreHTN+PreDM were, on average, overweight with a large waist circumference, displayed an exacerbated systemic inflammation and higher insulin resistance. They had elevated triglycerides, lower high-density lipoprotein cholesterol, leading to above average cardiac risk ratios and were significantly more likely to have two or three concomitant metabolic risk factors. High prevalence of Co-PreHTN+PreDM in healthy US adults, a strong correlate for dysregulated cardiometabolic risk factors, highlights a plausible accelerated pathway for early cardiovascular events.

Incremental weight loss improves cardiometabolic risk in extremely obese adults.

OBJECTIVE Excessively obese adults often acquire many metabolic disorders that put them at high risk for developing type 2 diabetes mellitus and cardiovascular disease. We investigated the hypothesis that cardiometabolic risk in a primary care cohort of 208 excessively obese adults (body mass index 40-60 kg/m(2), 48 with type 2 diabetes mellitus) would deteriorate with additional weight gain and improve incrementally beginning with 5% weight reduction. METHODS Further analysis of the Louisiana Obese Subjects Study of excessively obese patients enrolled and followed during 2005-2008 is reported. RESULTS Weight loss correlated significantly with improvements in fasting plasma glucose, triglycerides, high- and low-density lipoprotein cholesterol, uric acid, alanine aminotransferase, lactate dehydrogenase, and high-sensitivity C-reactive protein. Most parameters deteriorated with weight gain and progressively improved with 5% or more weight loss. Except for low-density lipoprotein cholesterol, all risk factors significantly improved with ≥ 20% loss of body weight. Among patients who had not been diagnosed with type 2 diabetes mellitus and had normoglycemia at baseline, median fasting plasma glucose increased significantly (13%) with stable or gained weight at 1 year, but did not change significantly with reduced weight. Although glucose levels did not change significantly in patients with type 2 diabetes mellitus who gained weight, a decline beginning after 5% weight reduction culminated in 25% glucose reduction with ≥ 20% weight loss. Resting blood pressure declined independently of weight change. CONCLUSION Very obese adults can improve their cardiometabolic risk under primary care weight management. Incremental success may help motivate further therapeutic weight reduction.

Actual medical and pharmacy costs for bariatric surgery: 6-year follow-up.

Objective To determine the change in total medical expenditures, total pharmacy expenditures, and subcategories of medical and pharmacy expenditures in obese individuals following weight loss surgery (WLS), and to compare these costs with expenditures in obese individuals not receiving WLS. Methods Louisiana Office of Group Benefits (OGB), the state-managed health insurer, invited members to be evaluated for insurance-covered WLS. Of 951 obese members who provided written consent to begin the WLS screening process, 40 were selected for surgery. Medical and pharmaceutical claims cost data of the 911 patients who did not have surgery and the 39 individuals who completed surgery were compared over a 2-year presurgical and 6-year postsurgical period. Results Total nonpharmacy medical costs were lower for WLS patients compared with non-WLS patients beginning 4 years postsurgery and lasting through 6 years postsurgery. No differences were found between WLS and non-WLS patients in expenditures for most medical subcategories examined, including emergency department, physical and occupational therapy, office visits, and laboratory/pathology; whereas sleep facility and all remaining medical expenditures not represented by a subcategory were lower for WLS patients during some postsurgery years. Total pharmacy costs were lower for WLS participants at 2 and 3 years postsurgery, but these lower costs were not maintained; however, costs remained lower for antidiabetic agents, antihypertensive agents, and dyslipidemic agents through all 6 postsurgery years under study. Conclusions The cost of WLS may begin to be recouped within the first 4 years postsurgery with continued effects 6 years postsurgery.

Predicting doubly labeled water energy expenditure from ambulatory activity.

The purpose of this study was to evaluate the potential for using accelerometer-determined ambulatory activity indicators (steps per day and cadence) to predict total energy expenditure (TEE) and physical activity energy expenditure (PAEE) derived from doubly labeled water (DLW). Twenty men and 34 women (20-36 years of age) provided complete anthropometric, accelerometer, resting metabolic rate (RMR), and DLW data. TEE and PAEE were determined for the same week that accelerometers were worn during waking hours. Accelerometer data included mean steps per day, peak 30-min cadence (average steps per minute for the highest 30 min of the day), and time spent in each incremental cadence band: 0 (nonmovement), 1-19 (incidental movement), 20-39 (sporadic movement), 40-59 (purposeful steps), 60-79 (slow walking), 80-99 (medium walking), 100-119 (brisk walking), and 120+ steps·min(-1) (indicative of all faster ambulatory activities). Regression analyses were employed to develop sex-specific equations for predicting TEE and PAEE. The final model predicting TEE included body weight, steps per day, and time in incremental cadence bands and explained 79% (men) and 65% (women) of the variability. The final model predicting PAEE included peak 30-min cadence, steps per day, and time in cadence bands and explained 76% (men) and 46% (women) of the variability. Time in cadence bands alone explained 39%-73% of the variability in TEE and 30%-63% of the variability in PAEE. Prediction models were stronger for men than for women.

Low vitamin D levels, prediabetes and prehypertension in healthy African American adults

AIMS To determine if customary lower serum vitamin D concentrations in healthy African American (AA) adults are associated with modest elevations in fasting plasma glucose (FPG) and/or resting blood pressure (BP). Numerous health disparities between African American (AA) and Caucasian American (CA) adults, especially those which increase cardiovascular morbidity and mortality, have been attributed to lower serum vitamin D concentrations in the AA. Prediabetes (PreDM) and prehypertension (PreHTN) are significantly more prevalent in healthy disease free CA adults with serum vitamin D concentrations below the 75th percentile for the Caucasian cohort. We hypothesized that despite overall lower serum vitamin D concentrations in AA, an increase in the prevalence for PreDM and PreHTN would be seen in those with low vitamin D levels. METHODS AND RESULTS Disease free AA adults in the National Health and Nutrition Examination Survey 2001-2006 were assessed. PreDM and PreHTN were diagnosed using the ADA and JNC 7 criteria: (FPG) 100-125 mg/dL and resting systolic (SBP) 120-139 and/or diastolic (DBP) 80-89 mm Hg, respectively. Logistic regression was employed to assess effects of low vitamin D concentrations on the odds for PreDM and PreHTN (n = 621). Age, gender and BMI adjusted odds ratio for co-morbid PreDM and PreHTN in AA men (n = 343) and women (n = 278) with vitamin D levels ≤45.4 versus >45.4 nmol/L was 2.02 (1.11, 3.68), (p < 0.021). CONCLUSIONS Evaluating serum vitamin D levels, with consideration for supplementation in seemingly healthy AA adults with prediabetes, prehypertension, or co-existing prediabetes and prehypertension, has merit.