Physical activity energy expenditure vs cardiorespiratory fitness level in impaired glucose metabolism.

AIM/HYPOTHESIS: Little is known about the relative roles of physical activity energy expenditure (PAEE) and cardiorespiratory fitness (CRF) as determinants of glucose regulation. The aim of this study was to examine the associations of PAEE and CRF with markers of glucose metabolism, and to test the hypothesis that CRF modifies the association between PAEE and glucose metabolism. METHODS: We analysed cross-sectional data from 755 adults from the Danish ADDITION-PRO study. On the basis of OGTT results, participants without known diabetes were classified as having normal glucose tolerance, isolated impaired fasting glycaemia (i-IFG), isolated impaired glucose tolerance (i-IGT), combined IFG + IGT or screen-detected diabetes mellitus. Markers of insulin sensitivity and beta cell function were determined. PAEE was measured using a combined heart rate and movement sensor. CRF (maximal oxygen uptake) was estimated using a submaximal 8 min step test. The associations were examined by linear regression analysis. Results were adjusted for relevant confounders. RESULTS: PAEE and CRF were reduced in individuals with i-IGT, combined IFG + IGT and screen-detected diabetes mellitus, but were not significantly different in individuals with i-IFG compared with those with normal glucose tolerance. When adjusting CRF for PAEE and vice versa, PAEE and CRF were both associated with lower fasting and 2 h insulin and higher peripheral insulin sensitivity. CRF was additionally associated with lower fasting and 2 h glucose and higher insulin sensitivity and beta cell function. There was no interaction between CRF and PAEE for any markers of glucose metabolism. CONCLUSIONS/INTERPRETATION: Only CRF, not PAEE, appears to be independently associated with plasma glucose levels and beta cell function, suggesting that CRF may be particularly important for glycaemic control.

Protocol for ADDITION-PRO: a longitudinal cohort study of the cardiovascular experience of individuals at high risk for diabetes recruited from Danish primary care.

BACKGROUND: Screening programmes for type 2 diabetes inevitably find more individuals at high risk for diabetes than people with undiagnosed prevalent disease. While well established guidelines for the treatment of diabetes exist, less is known about treatment or prevention strategies for individuals found at high risk following screening. In order to make better use of the opportunities for primary prevention of diabetes and its complications among this high risk group, it is important to quantify diabetes progression rates and to examine the development of early markers of cardiovascular disease and microvascular diabetic complications. We also require a better understanding of the mechanisms that underlie and drive early changes in cardiometabolic physiology. The ADDITION-PRO study was designed to address these issues among individuals at different levels of diabetes risk recruited from Danish primary care. METHODS/DESIGN: ADDITION-PRO is a population-based, longitudinal cohort study of individuals at high risk for diabetes. 16,136 eligible individuals were identified at high risk following participation in a stepwise screening programme in Danish general practice between 2001 and 2006. All individuals with impaired glucose regulation at screening, those who developed diabetes following screening, and a random sub-sample of those at lower levels of diabetes risk were invited to attend a follow-up health assessment in 2009-2011 (n=4,188), of whom 2,082 (50%) attended. The health assessment included detailed measurement of anthropometry, body composition, biochemistry, physical activity and cardiovascular risk factors including aortic stiffness and central blood pressure. All ADDITION-PRO participants are being followed for incident cardiovascular disease and death. DISCUSSION: The ADDITION-PRO study is designed to increase understanding of cardiovascular risk and its underlying mechanisms among individuals at high risk of diabetes. Key features of this study include (i) a carefully characterised cohort at different levels of diabetes risk; (ii) detailed measurement of cardiovascular and metabolic risk factors; (iii) objective measurement of physical activity behaviour; and (iv) long-term follow-up of hard clinical outcomes including mortality and cardiovascular disease. Results will inform policy recommendations concerning cardiovascular risk reduction and treatment among individuals at high risk for diabetes. The detailed phenotyping of this cohort will also allow a number of research questions concerning early changes in cardiometabolic physiology to be addressed.

Diurnal variation of hematology parameters in healthy young males: the Bispebjerg study of diurnal variations.

PURPOSE: To evaluate the influence of time of day on the circulating concentrations of 21 hematology parameters. MATERIALS AND METHODS: Venous blood samples were obtained under standardized circumstances from 24 healthy young men every third hour through 24 hours, nine time points in total. At each time point, the level of melatonin, iron, transferrin, transferrin saturation, ferritin, cobalamin, folate, red blood cells and white blood cells was measured. The data were analysed by rhythmometric statistical methods. The biological variations were calculated. RESULTS: Significant oscillation of melatonin (p < 0.0001) with an amplitude (amp) of 19.84 pg/ml and a peak level at 03:34 h confirmed the normal 24-hour rhythms of the participants. Erythrocytes (p < 0.0001, amp = 0.15 × 10(12)/L), hemoglobin (p < 0.0001, amp = 0.29 mmol/L), hematocrit (p < 0.0001, amp = 0.01), iron (p < 0.0001, amp = 4.00µmol/L), transferrin (p = 0.03, amp = 1.41µmol/L), transferrin saturation (p < 0.0001, amp = 6.37%) and folate (p < 0.0001, amp = 1.55nmol/L) oscillated significantly, with gradually falling mean levels through the day to nadir around midnight. Leukocyte count (p < 0.0001, amp = 0.78 × 10(9)/L), neutrophils (p = 0.001, 0.31 × 10(9)/L), eosinophils (p < 0.0001, amp = 0.04 × 10(9)/L), monocytes (p = 0.0009, amp = 0.06 × 10(9)/L), lymphocytes (p < 0.0001, amp = 0.49 × 10(9)/L) oscillated significantly with gradually increasing mean levels through the day peaking at midnight. Iron, leukocytes and hemoglobin had the highest 24 hour oscillations in proportion to the reference intervals of the parameters for healthy young men. CONCLUSIONS: Biochemical screenings are biased by diurnal variations, which must be considered when blood concentrations of these parameters are interpreted in the clinical setting.

Association between self-reported and objectively measured physical fitness level in a middle-aged population in primary care.

AIM: To investigate the association between self-reported physical fitness level obtained by a single-item question and objectively measured fitness level in 30- to 49-year-old men and women. METHODS: From the Danish 'Check Your Health Preventive Program' 2013-2014 fitness level was assessed in 2316 participants using the Aastrand test. Additionally, participants rated their physical fitness as high, good, average, fair or low. The association of self-reported- with objectively measured fitness level was analyzed by linear regression. Categories of self-reported- and objectively measured fitness level were cross-tabulated and agreement was quantified by Kappa statistics. Gender differences within categories were investigated by Poisson regression. RESULTS: Data from 996 men and 1017 women were analyzed (excluded, n = 303). In both men and women a higher self-reported fitness level was associated with a higher objectively measured fitness level (Rall = 0.42). Kappa agreement was 0.25. Poisson regression revealed that women rated their fitness level significantly lower than men (p < 0.001). CONCLUSION: A single-item question is a cost-effective way of measuring physical fitness level, but the method has low association and fair agreement when compared to the Aastrand test. Men tend to overestimate physical fitness more than women, which should be accounted for if using the question in primary care settings.

Combined heart rate- and accelerometer-assessed physical activity energy expenditure and associations with glucose homeostasis markers in a population at high risk of developing diabetes: the ADDITION-PRO study.

OBJECTIVE: Regular physical activity (PA) reduces the risk of developing type 2 diabetes, and different subtypes of dysglycemia have shown different associations with PA. To better understand the associations of PA and glucose homeostasis, we examined the association of objectively measured PA energy expenditure (PAEE) with detailed measures of glucose homeostasis. RESEARCH DESIGN AND METHODS: In 1,531 men and women, with low to high risk of developing type 2 diabetes, we measured 7 days of PAEE using a combined accelerometry and heart rate monitor (ActiHeart). Measures and indices of glucose homeostasis were derived from a 3-point oral glucose tolerance test in addition to measures of long-term glycemia (glycated hemoglobin A1c and advanced glycation end products). Associations of PAEE with glucose homeostasis markers were examined using linear regression models. RESULTS: Median age (IQR) was 66.6 years (62.1-71.6) (54% men) with a median ActiHeart wear time of 6.9 days (6.0-7.1) and PAEE level of 33.0 kJ/kg/day (23.5-46.1). In fully adjusted models, we found higher levels of PAEE to be positively associated with insulin sensitivity and negatively with insulin 2 h after glucose load (P<0.05). CONCLUSIONS: Even in an elderly population with low levels of PA, we found higher objectively measured PAEE levels to be associated with a more beneficial glucose metabolic profile. Although our findings are cross-sectional, they indicate that even without high-intensity exercise, increasing the overall level of PAEE slightly in an entire population at risk for developing type 2 diabetes may be a realistic and worthwhile goal to reach in order to achieve beneficial effect in terms of glucose metabolism.