Wednesday, November 30, 2016
A new study published in Diabetologia (the journal of the European Association for the Study of Diabetes [EASD]) suggests that a 'Sit Less' intervention ? breaking sitting with standing and light-intensity walking ? may be an alternative to structured exercise to promote blood sugar control in patients with type 2 diabetes, giving improved 24-hour glucose levels and improved insulin sensitivity.
The use of moderate to vigorous exercise is one of the cornerstones of prevention and treatment of type 2 diabetes, with current physical activity guidelines recommending a performance of at least 150 min per week of exercise at these intensities. Despite the proven effectiveness of such a regime, however, over 90% of the healthy population does not adhere to the guidelines. Non-compliance is likely to be even higher in those with type 2 diabetes, in which related comorbidities such as muscle weakness and peripheral neuropathy can be a barrier to physical exercise. An alternative approach is needed.
This study considered the possible benefits of a 'Sit Less' programme, replacing sitting time with standing and light-intensity walking, in comparison to the use of a conventional structured exercise regimen of the same energy expenditure. It was conducted by Bernard Duvivier, Department of Human Biology and Movement Science, NUTRIM School for Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre+, Netherlands, and colleagues.
The study involved 19 adults (13 men and 6 women) with type 2 diabetes, with a mean disease duration of 6 years, a mean HbA1c of 6.7% and a mean fasting plasma glucose of 7.88 mmol/l during screening. Their mean age was 63 years and the mean BMI was 30.5 kg/m2 (just within the definition of obese). A total of 14 participants were using glucose-lowering diabetes drugs and 13 were using lipid-lowering drugs (most often statins).
The participants followed three activity regimens - 'Sitting', 'Exercise' and 'Sit Less' - each lasting 4 days. During the sitting regimen participants were restricted to 1 hour/day of walking and 1 hour/day standing, with the remaining 14 hours spent sitting. During the exercise regimen approximately 1 hour/day of sitting time was replaced by supervised cycling on an ergometer at the research centre, in 20 minute bouts separated by 5 minutes rest. In the sit less regimen, 5 hours/day sitting were replaced by 2 hours walking and 3 hours standing, with participants encouraged to break up their sitting time every 30 minutes with small bouts of walking and standing throughout the day. The exercise and sit less regimens were designed to have comparable energy expenditure for each participant. The order of the regimens was randomised, and 10 days of usual lifestyle was maintained as a 'wash-out' period before and between regimens.
Diet was controlled with use of the participants' normal diet, supplemented during the last 36 hours of each regimen by the provision of pre-packed meals based on their energy requirements for each regimen. Glucose levels were measured continuously using a subcutaneous glucose monitor and also via the collection of blood glucose samples four times daily. The use of light-intensity walking was diarised and verified using advanced accelerometry (which monitors motion via multiple parameters). 24-hour glucose levels were analysed during the last 24 hours of each four-day regimen. On the day after each regimen, between 08.30 and 09.30 hours, after an overnight fast, blood was collected for glucose, insulin and lipid measurements.
The data were analysed to provide: 24 hour glucose concentration; incremental AUC for glucose (incremental area under the curve - a summary measure of glucose usage - the increase above fasting level over 24 hours); duration of hyperglycaemia; an average glucose concentration for each 30 minutes to indicate any bouts of hypoglycaemia; an estimate of insulin sensitivity; fasting triacylglycerol levels and non-esterified fatty acid (NEFA) levels.
The study found that the use of the sit less regimen led to significant improvements in insulin sensitivity, mean 24-hour glucose levels, 24-hour glucose excursions, durations of hyperglycaemia and fasting triacylglycerol levels, compared with sitting. Whilst positive effects for most variables (other than 24-hour glucose) were also found in the traditional exercise regimen, these were generally less potent than the improvements found for the sit less group. In addition, glucose level reductions, which can lead to hypoglycaemia and render some diabetic patients reluctant to perform structured exercise, were found to be less for the sit less regimen.
Previously it has been noted that a sedentary (inactive) lifestyle is associated with an increased risk of type 2 diabetes, and that regular interruption of sitting using small bouts of walking may be beneficial to insulin action and glucose control. This study, however, is the first to consider the effects of a sit less regimen for people with type 2 diabetes in free-living conditions. The outcome of the study fits the emerging picture that breaking up sedentary behaviour by light-intensity activities may be a potent way to help improve blood glucose control.
The authors suggest that sustained compliance with exercise programmes, especially by individuals with type 2 diabetes, is at best mediocre. Strategies to reduce sitting time are generally considered to be less demanding than structured exercise programmes and hence are more likely to have long-term compliance. The authors say that their findings "provide indications favouring the implementation of interventions targeting the breaking-up of sitting time over interventions involving structured exercise". As the volume of activities in this proof-of-concept study was high (an additional 2 hours walking and 3 hours standing during the sit less regimen in comparison to the other regimens), the authors suggest "that future long-term studies are needed to determine the volume of light-intensity activity that is feasible in daily life".
Monday, April 18, 2016
Friday, April 15, 2016
Thursday, April 7, 2016
While controlling blood pressure, blood sugar and LDL-cholesterol levels reduces the risk of cardiovascular disease in people with diabetes, only 7 percent of diabetic participants in three major heart studies had recommended levels of these three factors, according to research from the Heart Disease Prevention Program at the University of California, Irvine School of Medicine.
The findings illustrate the need for persons with diabetes to better manage their blood pressure, blood sugar and LDL-cholesterol levels, which are prime indicators of future cardiovascular disease. The diabetic participants surveyed in the UCI review were enrolled in the three heart studies between the late '80s and early 2000s, when treatment was not as good as it is now. Still, more recent data show that only 25 percent of Americans with diabetes achieve all three of these targets.
The good news is that those in the heart studies who did control all three factors had a 62 percent lower risk of developing cardiovascular disease, according to Nathan D. Wong, lead author of the UCI report, which appears online in Diabetes Care.
"But we have done a dismal job nationally at getting most of our patients with diabetes controlled for even just these three measures," said Wong, director of the Heart Disease Prevention Program and a cardiology professor at UCI.
"Since cardiovascular diseases - including coronary heart disease, stroke and heart failure - are leading causes of death for people with diabetes, these findings underscore the value of achieving target or lower levels of these modifiable risk factors," he added.
Wong and colleagues studied 2,018 adults (57 percent female) with diabetes mellitus but without known cardiovascular diseases who participated in the Atherosclerosis Risk in Communities Study, the Multi-Ethnic Study of Atherosclerosis or the Jackson Heart Study. Fifty-five percent were African American, 30 percent white, 11 percent Hispanic and 4 percent Asian/Pacific Islander.
The researchers compared measurements of the three key factors to American Diabetes Association guidelines that were in effect at the time - blood pressure under 130/80 mmHg, LDL (or bad) cholesterol less than 100 mg/dL and blood HbA1c (glycated hemoglobin) under 7 percent. Forty-one percent of the study group were on target in one of the three categories; 27 percent had achieved two of the benchmarks; but only 7 percent met the recommended scores in all three.
Study participants' control of individual and composite factors was also examined in relation to the occurrence of new cardiovascular events (including heart attacks, coronary deaths, strokes, heart failure, percutaneous interventions and bypass surgeries) over an average follow-up of 11 years.
Wong said that proper management of any one factor translated to a 36 percent lower risk, proper management of any two factors was linked to a 52 percent lower risk, and proper management of all three factors correlated to a 62 percent lower risk of cardiovascular events compared to those without any factors controlled.
Blood pressure management appeared to benefit African Americans and women more than other ethnic groups or men; however, the converse was true for LDL control.
"Our analysis of three large U.S. cohorts including persons in whom diabetes has been diagnosed shows those who were at target levels for HbA1c, blood pressure and LDL to have substantially lower risks for cardiovascular disease than persons with diabetes who were not at target levels for such factors," Wong said. "These findings emphasize the importance of composite control of these modifiable risk factors to better address the cardiovascular disease risks seen in persons with diabetes, the need for the development of healthcare strategies to better ensure such management, and the need for studies to evaluate and eliminate barriers to risk factor control in persons with diabetes."