Showing papers by "David W. Dunstan published in 2007"

Risk of Cardiovascular and All-Cause Mortality in Individuals With Diabetes Mellitus, Impaired Fasting Glucose, and Impaired Glucose Tolerance The Australian Diabetes, Obesity, and Lifestyle Study (AusDiab)

Abstract: Background— Diabetes mellitus increases the risk of cardiovascular disease (CVD) and all-cause mortality. The relationship between milder elevations of blood glucose and mortality is less clear. This study investigated whether impaired fasting glucose and impaired glucose tolerance, as well as diabetes mellitus, increase the risk of all-cause and CVD mortality. Methods and Results— In 1999 to 2000, glucose tolerance status was determined in 10 428 participants of the Australian Diabetes, Obesity, and Lifestyle Study (AusDiab). After a median follow-up of 5.2 years, 298 deaths occurred (88 CVD deaths). Compared with those with normal glucose tolerance, the adjusted all-cause mortality hazard ratios (HRs) and 95% confidence intervals (CIs) for known diabetes mellitus and newly diagnosed diabetes mellitus were 2.3 (1.6 to 3.2) and 1.3 (0.9 to 2.0), respectively. The risk of death was also increased in those with impaired fasting glucose (HR 1.6, 95% CI 1.0 to 2.4) and impaired glucose tolerance (HR 1.5, 95% ...

Objectively measured light- intensity physical activity is independently associated with 2-h plasma glucose

Abstract: Objective : We examined the associations of objectively measured sedentary time, light-intensity physical activity, and moderate- to vigorous-intensity activity with fasting and 2-h postchallenge plasma glucose in Australian adults. Research Design and Methods : A total of 67 men and 106 women (mean age ± SD 53.3 ± 11.9 years) without diagnosed diabetes were recruited from the 2004–2005 Australian Diabetes, Obesity, and Lifestyle (AusDiab) study. Physical activity was measured by Actigraph accelerometers worn during waking hours for 7 consecutive days and summarized as sedentary time (accelerometer counts/min Results : After adjustment for confounders (including waist circumference), sedentary time was positively associated with 2-h plasma glucose ( b = 0.29, 95% CI 0.11–0.48, P = 0.002); light-intensity activity time ( b = –0.25, –0.45 to –0.06, P = 0.012) and moderate- to vigorous-intensity activity time ( b = –1.07, –1.77 to –0.37, P = 0.003) were negatively associated. Light-intensity activity remained significantly associated with 2-h plasma glucose following further adjustment for moderate- to vigorous-intensity activity ( b = –0.22, –0.42 to –0.03, P = 0.023). Associations of all activity measures with fasting plasma glucose were nonsignificant ( P > 0.05). Conclusions : These data provide the first objective evidence that light-intensity physical activity is beneficially associated with blood glucose and that sedentary time is unfavorably associated with blood glucose. These objective data support previous findings from studies using self-report measures, and suggest that substituting light-intensity activity for television viewing or other sedentary time may be a practical and achievable preventive strategy to reduce the risk of type 2 diabetes and cardiovascular disease.

Association of Television Viewing With Fasting and 2-h Postchallenge Plasma Glucose Levels in Adults Without Diagnosed Diabetes

Abstract: OBJECTIVE —We examined the associations of television viewing time with fasting plasma glucose (FPG) and 2-h postchallenge plasma glucose (2-h PG) levels in Australian adults. RESEARCH DESIGN AND METHODS —A total of 8,357 adults aged >35 years who were free from diagnosed diabetes and who attended a population-based cross-sectional study (Australian Diabetes, Obesity and Lifestyle Study [AusDiab]) were evaluated. Measures of FPG and 2-h PG were obtained from an oral glucose tolerance test. Self-reported television viewing time (in the previous week) was assessed using an interviewer-administered questionnaire. Homeostasis model assessment (HOMA) of insulin sensitivity (HOMA-%S) and β-cell function (HOMA-%B) were calculated based on fasting glucose and insulin concentrations. RESULTS —After adjustment for confounders and physical activity time, time spent watching television in women was positively associated with 2-h PG, log fasting insulin, and log HOMA-%B and inversely associated with log HOMA-%S ( P P for trend = 0.02). CONCLUSIONS —Our findings highlight the unique deleterious relationship of sedentary behavior (indicated by television viewing time) and glycemic measures independent of physical activity time and adiposity status. These relationships differed according to sex and type of glucose measurement, with the 2-h PG measure being more strongly associated with television viewing. The findings suggest an important role for reducing sedentary behavior in the prevention of type 2 diabetes and cardiovascular disease, especially in women.

The inverse relationship between number of steps per day and obesity in a population-based sample – the AusDiab study

Abstract: Background: Physical activity (PA) is inversely associated with obesity but the effect has been difficult to quantify using questionnaires. In particular, the shape of the association has not yet been well described. Pedometers provide an opportunity to better characterize the association. Methods: Residents of households over the age of 25 years in randomly selected census districts in Tasmania were eligible to participate in the AusDiab cross-sectional survey conducted in 1999–2000. 1848 completed the AusDiab survey and 1126 of these (609 women and 517 men) wore a pedometer for 2-weekdays. Questionnaire data on recent PA, TV time and other factors were obtained. The outcomes were waist circumference (in cm) and body mass index (BMI) (kg/m2). Results: Increasing daily steps were associated with a decline in the obesity measures. The logarithmic nature of the associations was indicated by a sharper decline for those with lower daily steps. For example, an additional 2000 steps for those taking only 2000 steps per day was associated with a reduction of 2.8 (95% confidence interval (CI): 2.1,4.4) cm in waist circumference among men (for women; 2.2 (95% CI: 0.6, 3.9 cm)) with a baseline of only 2000, steps compared to a 0.7 (95% CI 0.3, 1.1) cm reduction (for women; 0.6 (95% CI: 0.2, 1.0)) for those already walking 10 000 steps daily. In the multivariable analysis, clearer associations were detected for PA and these obesity measures using daily step number rather than PA time by questionnaire. Interpretation: Pedometer measures of activity indicate that the inverse association between recent PA and obesity is logarithmic in form with the greatest impact for a given arithmetic step number increase seen at lower levels of baseline activity. The findings from this study need to be examined in prospective settings.

Objectively measured sedentary time and light-intensity physical activity are independently associated with components of the metabolic syndrome: The AusDiab study

Abstract: Background and Aims: Physical activity and sedentary behaviour are keymodifiable risk factors for components of the metabolic syndrome. However,studies typically have used physical activity variables derived from impreciseself-report measures. We examined the associations of objectively-measuredsedentary time and light-intensity physical activity with components of themetabolic syndrome in Australian adults without known diabetes.Materials and Methods: 70 men and 108 women (mean age 53.4, range30 to 87) were recruited from the 2004n2005 Australian Diabetes, Obesity,and Lifestyle (AusDiab) study. Physical activity was measured by Actigraphaccelerometers worn during waking hours for seven consecutive days, anddivided into sedentary time (counts/minute l100), light-intensity (counts/minute 100n1951), and moderate-to-vigorous intensity (counts/minuteg1952). An oral glucose tolerance test was used to obtain fasting and 2-hrplasma glucose, serum-triglycerides, and HDL-C. Waist circumference andblood pressure were measured at the testing site. Components of the metabolicsyndrome were dichotomised according to the current IDF definition, andreported as central obesity, raised triglycerides, blood pressure, fasting plasmaglucose, and 2-hr plasma glucose, and reduced HDL-C.Results: In logistic regression analyses adjusted for age, sex, time accelerometerworn, income, education, and moderate-to-vigorous intensity activity, eachadditional hour/day of sedentary time was associated with an increased riskof central obesity (OR=1.40, p=0.017); while each hour/day of light intensityactivity was associated with a reduced risk (OR=0.69, p=0.009). When waistcircumference (cm) was included in the model, each hour/day of sedentarytime was associated with an increased risk of raised triglycerides (OR=1.44,p=0.046), raised 2-hr plasma glucose (OR=1.72, p=0.052), and reducedHDL-C (OR=1.56, p=0.009); each hour/day of light-intensity activity wasassociated with a significantly lower risk of raised triglycerides (OR=0.66,p=0.028), raised 2-hr plasma glucose (OR=0.55, p=0.036), and reducedHDL-C (OR=0.65, p=0.012). The associations of sedentary time and light-intensityactivity with raised blood pressure and fasting blood glucose werenot statistically significant (pg0.1).Conclusion: These findings provide some of the first evidence from objectiveactivity data that sedentary time is unfavourably associated with componentsof the metabolic syndrome, particularly central obesity, triglycerides, 2-hrplasma glucose, and HDL-C, and that light-intensity activity is beneficiallyassociated. Importantly, these associations were independent of moderateto-vigorous intensity activity. The findings suggest that substituting lightintensityactivity for television viewing or other sedentary time may be apractical and achievable strategy to improve metabolic risk in adults.Supported by Queensland Government Growing the Smart State PhD fund,NHMRC

Associations of sitting time with components of the metabolic syndrome in adults without diagnosed diabetes - The AusDiab Study

Abstract: Background and Aims: Several studies have shown that sedentary behaviour may be an important contributor to poor health outcomes. However, most studies have focused on leisure time behaviours such as time spent watching television. Less is known about the association of sedentary behaviours in both leisure and non-leisure time on metabolic outcomes. We have examined the associations of self-reported time spent sitting and components of the metabolic syndrome in Australian adults without diabetes.Materials and Methods: The Australian Diabetes, Obesity and Lifestyle Study (AusDiab) is a nationally representative population-based survey of 11,247 adults aged 25 years with baseline measurements obtained between 1999 and 2000. The present analyses include a total of 5,749 adults who attended the 5-year follow-up and who were free from diagnosed diabetes. Fasting measures of plasma glucose, serum triglycerides and HDL-C and 2hrPG were obtained from an oral glucose tolerance test. Self-reported time spent sitting (hrs/day) was assessed using an interviewer-administered questionnaire.Waist circumference, height and resting blood pressure were measured at the testing site. The log transformation of the triglyceride measure was used in the analysis. All regression models were adjusted for age, education, employment status and physical activity time. Data are presented as regression coefficients (95% CI).Results: The mean (SD) sitting time (hrs/day) for women and men was 5.1 (2.6) and 5.5 (2.7) respectively. In both men and women, sitting time was positively associated with 2hrPG , log-transformed triglycerides, and waist circumference and inversely associated with HDL-C (P value range: 0.001–0.01). The mean differences between the top tertile and bottom tertile were: 2hrPG [men: 0.2 mmol/l (0.01 to 0.40), women 0.3 mmol/l (0.14 to 0.44)], log-transformed triglycerides [men 0.1 (0.05 to 0.16), women 0.1 (0.06 to 0.14)], waist [men 2.4 cm (1.3 to 3.4), women 3.3 cm (2.2 to 4.4)] and HDL-C [men –0.06 mmol/l (–0.09 to –0.03), women (–0.05 mmol/l (–0.09 to –0.02)]. Systolic and diastolic blood pressure were positively associated with sitting time in women only (both P = 0.01). No association was observed with FBG. The associations observed for 2hrPG and log-triglycerides in women and logtriglycerides and HDL-C in men remained significant (P < 0.003) following further adjustment for waist circumference. In regression models containing both weekday and weekend sitting time as covariates, weekday sitting time was associated with log-triglycerides in men and women (both P < 0.01) and HDL-C and waist in men (P < 0.001). Weekend sitting time was associated with 2hrPG in both men and women (both P < 0.05) and log-triglycerides (P = 0.04) and waist (P = 0.001) in women. Conclusion: These findings highlight the unique deleterious relationships of sedentary behaviour (indicated by sitting time) and components of the metabolic syndrome, independent of physical activity time. Population strategies to reduce the risk of developing the metabolic syndrome should focus not only on increasing physical activity, but also on reducing sedentary behaviours, such as time spent sitting.