• Correspondence of continuous interstitial glucose measurement against arterialised and capillary glucose following an oral glucose tolerance test in healthy volunteers

      Dye, Louise; Mansfield, Michael; Lasikiewicz, Nicola; Mahawish, Lena; Schnell, Rainer; Talbot, Duncan; Chauhan, Hitesh; Croden, Fiona; Lawton, Clare (2009-08-13)
      The aim of the present study was to validate the Glucodayw continuous interstitial ambulatory glucose-monitoring device (AGD) against plasma glucose measured from arterialised venous (AV) and glucose from capillary whole blood (finger prick, FP) in non-diabetic subjects in response to an oral glucose tolerance test. Fifteen healthy overweight men (age 30–49 years, BMI 26–31 kg/m2 ) participated. Glucose levels were measured before, during and after consumption of an oral 75 g glucose load using twelve FP samples and forty-four 1 ml AV blood samples during 180 min. Interstitial glucose was measured via the AGD. Three venous samples for fasting insulin were taken to estimate insulin resistance. Profiles of AGD, AV and FP glucose were generated for each participant. Glucose values for each minute of the measurement period were interpolated using a locally weighted scatterplot smoother. Data were compared using Bland–Altman plots that showed good correspondence between all pairs of measurements. Concordance between the three methods was 0·8771 (Kendall’s W, n 15, P,0·001). Concordance was greater between AV and FP (W ¼ 0·9696) than AGD and AV (W ¼ 0·8770) or AGD and FP (W ¼ 0·8764). Analysis of time to peak glucose indicated that AGD measures lagged approximately 15 min behind FP and AV measures. Percent body fat was significantly correlated with time to peak glucose levels for each measure, while BMI and estimated insulin resistance (homeostatic model assessment, HOMA) were not. In conclusion, AGD shows good correspondence with FP and AV glucose measures in response to a glucose load with a 15 min time lag. Taking this into account, AGD has potential application in nutrition and behaviour studies.
    • Exploration of basal diurnal salivary cortisol profiles in middle-aged adults: Associations with sleep quality and metabolic parameters

      Lasikiewicz, Nicola; Hendrickx, Hilde; Talbot, Duncan; Dye, Louise (Elsevier, 2007-09-27)
      The use of saliva samples is a practical and feasible method to explore basal diurnal cortisol profiles in free-living research. This study explores a number of psychological and physiological characteristics in relation to the observed pattern of salivary cortisol activity over a 12-h period with particular emphasis on sleep. Basal diurnal cortisol profiles were examined in a sample of 147 volunteers (mean age 46.2177.18 years). Profiles were constructed for each volunteer and explored in terms of the area under the curve (AUC) of the cortisol-awakening response with samples obtained immediately upon waking (0, 15, 30 and 45 min post waking) and at 3, 6, 9 and 12 h post waking to assess diurnal decline. Diurnal mean of cortisol was based on the mean of cortisol at time points 3, 6, 9 and 12 h post waking. Psychological measures of perceived stress and sleep were collected with concurrent biological assessment of fasting plasma glucose, insulin, blood lipids and inflammatory markers. Blunted cortisol profiles, characterised by a reduced AUC, were observed in the majority (78%) of a middle-aged sample and were associated with significantly poorer sleep quality and significantly greater waist-hip ratio (WHR). Blunted cortisol profiles were further associated with a tendency to exhibit a less favourable metabolic profile. These findings suggest that reduced cortisol secretion post waking may serve as an additional marker of psychological and biological vulnerability to adverse health outcomes in middle-aged adults.
    • Exploring stress-induced cognitive impairment in middle aged, centrally obese adults

      Lasikiewicz, Nicola; Hendrickx, Hilde; Talbot, Duncan; Dye, Louise (2013-01)
      Extensive research has shown that psychosocial stress can induce cognitive impairment. However, few studies have explored impairment following acute stress exposure in individuals with central obesity. Central obesity co-occurs with glucocorticoid excess and can lead to elevated cortisol responses to stress. It is not clear whether centrally obese individuals exhibit greater cognitive impairment following acute stress. Cortisol responses to stress versus no-stress control were compared in 66 high- and low waist to hip ratio (WHR) middle-aged adults (mean age of 46 ± 7.17 years). Cognitive performance post exposure was assessed using Cambridge Automated Neuropsychological Test Battery. It was hypothesised that high WHR would exhibit greater cortisol in response to stress exposure and would show poorer cognitive performance. Males, particularly of high WHR, tended to secrete greater cortisol during stress exposure. Exposure to stress and increasing WHR were specifically associated with poorer performance on declarative memory tasks (spatial recognition memory and paired associates learning). These data tentatively suggest a reduction in cognitive performance in those with central obesity following exposure to acute stress. Further research is needed to elucidate the effects of stress on cognition in this population.
    • Stress, cortisol and central obesity in middle aged adults

      Lasikiewicz, Nicola; Hendrickx, Hilde; Talbot, Duncan; Dye, Louise; University of Chester (Karger, 2013-05-24)
      Introduction: Obesity is associated with various psychological and physiological disturbances. Of interest is the relationship between central obesity and psychological stress. Central obesity is characterised by increased adipose tissue, often associated with glucocorticoid excess, specifically, the stress hormone cortisol. Consequently, a disturbed cortisol basal diurnal rhythm and impaired responses to psychological stress in middle aged adults with central obesity may be observed. Method: In study one, basal diurnal cortisol profiles were examined (n=147; mean = 46.21 ± 7.18 years) in a sample of high and low waist-hip ratio (WHR) males and females. Profiles were explored in terms of the area under the curve (AUC) of the cortisol-awakening response and diurnal decline. In study two, cortisol responses to a psychological stressor versus no-stress control (n=66; mean = 46 ± 7.17 years) in a sample of high and low WHR individuals were explored. Results: Blunted cortisol profiles, characterised by a reduced AUC, were observed in the majority (78%) of a middle-aged sample and were associated with significantly greater WHR. Further, blunted cortisol profiles were associated with a less favourable metabolic profile. When exposed to a psychological stressor, high WHR individuals, specifically males, tended to secrete greater cortisol. Conclusion: The findings suggest that central obesity is associated with altered cortisol responsivity. This highlights the vulnerability of high WHR individuals to stress related illness and disease. Further research, however, is required to elucidate whether stress exposure increases the propensity for central obesity or whether central obesity elevates stress responsivity.