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1.
Blood glucose concentration is unchanged during exposure to acute normobaric hypoxia in healthy humans.
Chan, JS, Chiew, AE, Rimke, AN, Chan, G, Rampuri, ZH, Kozak, MD, Boulé, NG, Steinback, CD, Davenport, MH, Day, TA
Physiological reports. 2021;(15):e14932
Abstract
Normal blood [glucose] regulation is critical to support metabolism, particularly in contexts of metabolic stressors (e.g., exercise, high altitude hypoxia). Data regarding blood [glucose] regulation in hypoxia are inconclusive. We aimed to characterize blood [glucose] over 80 min following glucose ingestion during both normoxia and acute normobaric hypoxia. In a randomized cross-over design, on two separate days, 28 healthy participants (16 females; 21.8 ± 1.6 years; BMI 22.8 ± 2.5 kg/m2 ) were randomly exposed to either NX (room air; fraction of inspired [FI ]O2 ~0.21) or HX (FI O2 ~0.148) in a normobaric hypoxia chamber. Measured FI O2 and peripheral oxygen saturation were both lower at baseline in hypoxia (p < 0.001), which was maintained over 80 min, confirming the hypoxic intervention. Following a 10-min baseline (BL) under both conditions, participants consumed a standardized glucose beverage (75 g, 296 ml) and blood [glucose] and physiological variables were measured at BL intermittently over 80 min. Blood [glucose] was measured from finger capillary samples via glucometer. Initial fasted blood [glucose] was not different between trials (NX:4.8 ± 0.4 vs. HX:4.9 ± 0.4 mmol/L; p = 0.47). Blood [glucose] was sampled every 10 min (absolute, delta, and percent change) following glucose ingestion over 80 min, and was not different between conditions (p > 0.77). In addition, mean, peak, and time-to-peak responses during the 80 min were not different between conditions (p > 0.14). There were also no sex differences in these blood [glucose] responses in hypoxia. We conclude that glucose regulation is unchanged in young, healthy participants with exposure to acute steady-state normobaric hypoxia, likely due to counterbalancing mechanisms underlying blood [glucose] regulation in hypoxia.
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The Effects of Intermittent Fasting on Glycemic Control and Body Composition in Adults with Obesity and Type 2 Diabetes: A Systematic Review.
Vitale, R, Kim, Y
Metabolic syndrome and related disorders. 2020;(10):450-461
Abstract
The purpose of this study was to evaluate the effects of intermittent fasting on glycemic control and body composition in adults with obesity and type 2 diabetes. Although intermittent fasting has shown some promise in improving glucoregulatory indicators and body composition in adults with obesity, there is currently no systematic review evaluating these effects in adults with obesity and type 2 diabetes. A database search of PubMed, CINHAL, and MEDLINE identified five studies that met inclusion criterion. All studies were randomized controlled trials in adult subjects (n = 46-137) with type 2 diabetes and a body mass index of ≥30 kg/m2. Four different intermittent fasting regimens were reviewed. All fasting regimens revealed strong evidence to support intermittent fasting as a feasible diet to improve glycemia and body composition measures within 12-24 weeks. Follow-up 12-18 months after intermittent fasting did not show promising results for continued weight loss and improved glycemic control. The majority of the studies demonstrated insignificant differences between intermittent fasting and continuous energy restriction for measures of glycated hemoglobin a1c and body composition. More data on intermittent fasting in adults with obesity and type 2 diabetes are needed to determine its benefits within this patient population. Future research should include consistent fasting regimens and larger sample sizes to improve the reliability and generalizability of the data. Also, consistent follow-up after a fasting intervention may enhance long-term benefits and should be considered in future research.
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The value of Continuous Glucose Monitoring and Self-Monitoring of Blood Glucose in patients with Gestational Diabetes Mellitus during Ramadan fasting.
Afandi, B, Hassanein, M, Roubi, S, Nagelkerke, N
Diabetes research and clinical practice. 2019;:260-264
Abstract
INTRODUCTION In order to achieve the recommended glycemic control, women with Gestational Diabetes Mellitus (GDM) are instructed to self-monitor blood glucose (SMBG) regularly. The purpose of this study was to evaluate glucose readings provided by Continuous Glucose Monitoring (CGM) and SMBG in GDM patients during Ramadan fasting. METHODS This is a prospective observational study that recruited GDM patients treated with diet ± metformin were enrolled. They agreed to wear the iPro®2 ProfessionalCGM device and to do SMBG by glucose reading meters, during fasting and after meals. We evaluated the rates of hypoglycemia and hyperglycemia in each approach. The frequency and timing of SMBG was investigated. RESULTS Twenty-five patients were recruited. A total of 36,628 readings by CGM device and 408 readings using glucose meters and were captured. Average glucose level was 103 ± 8 mg/dl (5.7 ± 0.4 mmol/l) and 113 ± 14 mg/d (6.28 ± 0.8 mmol/L) on CGM and glucose meters respectively. The rate of hyperglycemia was 5.65% and 14.2% and hypoglycemia was 4.35% and 1.5% using CGM and glucose meters respectively. While all hypoglycemic episodes occurred between 16:00-19:00 in both approaches, only 38 readings (9%) of SMBG readings were done in that time frame. CONCLUSION Although the frequency of SMBG using glucose meters for women with GDM and fasting Ramadan was acceptable, the timing was not. CGM detected more hypoglycemia and less hyperglycemia than SMBG. Relying on Intermittent SMBG in the management of GDM patients during Ramadan fasting might be misleading.
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The effect of intermittent compared with continuous energy restriction on glycaemic control in patients with type 2 diabetes: 24-month follow-up of a randomised noninferiority trial.
Carter, S, Clifton, PM, Keogh, JB
Diabetes research and clinical practice. 2019;:11-19
Abstract
AIMS: We investigated the effects of intermittent compared to continuous energy restriction on glycaemic control in patients with type 2 diabetes mellitus. METHODS Adults (N = 137) with type 2 diabetes (mean [SD] HbA1c level, 7.3% (56 mmol/mol) [1.3%] [14.2 mmol/mol]) were randomised to one of two diets for 12 months. The intermittent group (n = 70) followed a 2100-2500 kJ (500-600 kcal) diet 2 non-consecutive days/week and their usual diet for 5 days/week. The continuous group (n = 67) followed a 5000-6300 kJ (1200-1500 kcal) diet for 7 days/week. Follow-up occurred at 24 months, 12 months after the completed intervention. The primary outcome was change in HbA1c and the secondary outcome was weight loss. RESULTS Intention-to-treat analysis showed an increase in mean [SEM] HbA1c level at 24 months in both the continuous and intermittent groups (0.4% [0.3%] vs 0.1% [0.2%] respectively; P = 0.32) (4.4 [3.3 mmol/mol] vs 1.1 [2.2 mmol/mol]; P = 0.32), with a between-group difference of 0.3% (90% CI, -0.31 to 0.83%) (3.3 mmol/mol [90% CI, -3.2 to 9.1 mmol/mol]) outside the prespecified boundary of ± 0.5% (5.5 mmol/mol), so statistical equivalence was not shown. Weight loss was maintained (P < 0.001) at -3.9 kg [1.1 kg] in both groups at 24 months, with a between-group difference of 0.07 kg (90% CI, -2.5 to 2.6 kg) outside the prespecified boundary of ±2.5 kg. There were no significant differences between groups in body composition, fasting glucose levels, lipid levels, or total medication effect score at 24 months, which remained less than baseline. CONCLUSIONS In this prospective analysis weight loss was maintained but despite this HbA1c increased to above baseline levels in both groups.
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Dietary patterns and management of type 2 diabetes: A systematic review of randomised clinical trials.
Papamichou, D, Panagiotakos, DB, Itsiopoulos, C
Nutrition, metabolism, and cardiovascular diseases : NMCD. 2019;(6):531-543
Abstract
BACKGROUND AND AIM The aim of the present review is to examine evidence from published studies on the effectiveness of six or more months of low carbohydrate, macrobiotic, vegan, vegetarian, Mediterranean and intermittent fasting (IF) diets compared to low fat diets on diabetes control and management. METHODS AND RESULTS In accordance with PRISMA guidelines, Cochrane CENTRAL, PubMed and Scopus databases were systematically searched for relevant studies. Twenty randomised controlled trials (RCTs) > 6 months that investigated the effectiveness of various dietary patterns on type 2 diabetes mellitus (T2DM) were included. Risk of bias was assessed using the Cochrane tool. There were no significant differences in glycemic control, weight and lipids for the majority of low carbohydrate diets (LCDs) compared to low fat diets (LFDs). Four out of fifteen LCD interventions showed better glycemic control while weight loss was greater in one study. The Mediterranean dietary pattern demonstrated greater reduction in body weight and HbA1c levels and delayed requirement for diabetes medications. The vegan and macrobiotic diet demonstrated improved glycemic control, while the vegetarian diet showed greater body weight reduction and insulin sensitivity. CONCLUSIONS Although more long-term intervention trials are required, mounting evidence supports the view that vegan, vegetarian and Mediterranean dietary patterns should be implemented in public health strategies, in order to better control glycemic markers in individuals with T2DM.
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Effect of combining pre-exercise carbohydrate intake and repeated short sprints on the blood glucose response to moderate-intensity exercise in young individuals with Type 1 diabetes.
Soon, WHK, Guelfi, KJ, Davis, EA, Smith, GJ, Jones, TW, Fournier, PA
Diabetic medicine : a journal of the British Diabetic Association. 2019;(5):612-619
Abstract
AIMS: To determine whether pre-exercise ingestion of carbohydrates to maintain stable glycaemia during moderate-intensity exercise results in excessive hyperglycaemia if combined with repeated sprints in individuals with Type 1 diabetes. METHODS Eight overnight-fasted people with Type 1 diabetes completed the following four 40-min exercise sessions on separate days in a randomized counterbalanced order under basal insulinaemic conditions: continuous moderate-intensity exercise at 50% V˙O2 peak; intermittent high-intensity exercise (moderate-intensity exercise interspersed with 4-s sprints every 2 min and a final 10-s sprint); continuous moderate-intensity exercise with prior carbohydrate intake (~10 g per person); and intermittent high-intensity exercise with prior carbohydrate intake. Venous blood was sampled during and 2 h after exercise to measure glucose and lactate levels. RESULTS The difference in marginal mean time-averaged area under the blood glucose curve between continuous moderate-intensity exercise + prior carbohydrate and intermittent high-intensity exercise + prior carbohydrate during exercise and recovery was not significant [0.2 mmol/l (95% CI -0.7, 1.1); P = 0.635], nor was the difference in peak blood glucose level after adjusting for baseline level [0.2 mmol/l (95% CI -0.7, 1.1); P = 0.695]. The difference in marginal mean time-averaged area under the blood glucose curve between continuous moderate-intensity and intermittent high-intensity exercise during exercise and recovery was also not significant [-0.2 mmol/l (95% CI -1.2, 0.8); P = 0.651]. CONCLUSIONS When carbohydrates are ingested prior to moderate-intensity exercise, adding repeated sprints is not significantly detrimental to glycaemic management in overnight fasted people with Type 1 diabetes under basal insulin conditions.
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Effect of Intermittent Compared With Continuous Energy Restricted Diet on Glycemic Control in Patients With Type 2 Diabetes: A Randomized Noninferiority Trial.
Carter, S, Clifton, PM, Keogh, JB
JAMA network open. 2018;(3):e180756
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Abstract
IMPORTANCE Intermittent energy restriction is an alternative weight loss method that is becoming popular; however, to date, there are no long-term clinical trials of intermittent energy restriction in patients with type 2 diabetes. OBJECTIVE To compare the effects of intermittent energy restriction (2 days per week) with those of continuous energy restriction on glycemic control and weight loss in patients with type 2 diabetes during a 12-month period. DESIGN, SETTING, AND PARTICIPANTS Adult participants (N = 137) with type 2 diabetes were randomized 1:1 to parallel diet groups (intermittent energy restriction [n = 70] or continuous energy restriction [n = 67]) between April 7, 2015, and September 7, 2017, at the University of South Australia. Medications likely to cause hypoglycemia were reduced at baseline according to the medication management protocol. INTERVENTIONS An intermittent energy restriction diet (500-600 kcal/d) followed for 2 nonconsecutive days per week (participants followed their usual diet for the other 5 days) or a continuous energy restriction diet (1200-1500 kcal/d) followed for 7 days per week for 12 months. MAIN OUTCOMES AND MEASURES The primary outcome was change in hemoglobin A1c (HbA1c) level, with equivalence prespecified by a 90% CI margin of ±0.5%. The secondary outcome was weight loss with equivalence set at ±2.5 kg (±1.75 kg for fat mass loss and ±0.75 kg for fat-free mass loss). All other outcomes were tested for superiority. RESULTS Of the 137 randomized participants (77 women and 60 men; mean [SD] age, 61.0 [9.1] years; mean [SD] body mass index, 36.0 [5.8] [calculated as weight in kilograms divided by height in meters squared]; and mean [SD] HbA1c level, 7.3% [1.3%]), 97 completed the trial. Intention-to-treat analysis showed similar reductions in mean (SEM) HbA1c level between the continuous and intermittent energy restriction groups (-0.5% [0.2%] vs -0.3% [0.1%]; P = .65), with a between-group difference of 0.2% (90% CI, -0.2% to 0.5%) meeting the criteria for equivalence. Mean (SEM) weight change was similar between the continuous and intermittent energy restriction groups (-5.0 [0.8] kg vs -6.8 [0.8] kg; P = .25), but the between-group difference did not meet the criteria for equivalence (-1.8 kg; 90% CI, -3.7 to 0.07 kg), nor did the between-group difference in fat mass (-1.3 kg; 90% CI, -2.8 to 0.2 kg) or fat-free mass (-0.5 kg; 90% CI, -1.4 to 0.4 kg). There were no significant differences between groups in final step count, fasting glucose levels, lipid levels, or total medication effect score at 12 months. Effects did not differ using completers analysis. Hypoglycemic or hyperglycemic events in the first 2 weeks of treatment were similar between the continuous and intermittent energy restriction groups (mean number [SEM] of events, 3.2 [0.7] vs 4.9 [1.4]; P = .28), affecting 35% of participants (16 of 46) using sulfonylureas and/or insulin. CONCLUSIONS AND RELEVANCE Intermittent energy restriction is an effective alternative diet strategy for the reduction of HbA1c and is comparable with continuous energy restriction in patients with type 2 diabetes. TRIAL REGISTRATION anzctr.org.au Identifier: ACTRN12615000383561.
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Dietary Interventions for the Prevention of Type 2 Diabetes in High-Risk Groups: Current State of Evidence and Future Research Needs.
Guess, ND
Nutrients. 2018;(9)
Abstract
A series of large-scale randomised controlled trials have demonstrated the effectiveness of lifestyle change in preventing type 2 diabetes in people with impaired glucose tolerance. Participants in these trials consumed a low-fat diet, lost a moderate amount of weight and/or increased their physical activity. Weight loss appears to be the primary driver of type 2 diabetes risk reduction, with individual dietary components playing a minor role. The effect of weight loss via other dietary approaches, such as low-carbohydrate diets, a Mediterranean dietary pattern, intermittent fasting or very-low-energy diets, on the incidence of type 2 diabetes has not been tested. These diets-as described here-could be equally, if not more effective in preventing type 2 diabetes than the tested low-fat diet, and if so, would increase choice for patients. There is also a need to understand the effect of foods and diets on beta-cell function, as the available evidence suggests moderate weight loss, as achieved in the diabetes prevention trials, improves insulin sensitivity but not beta-cell function. Finally, prediabetes is an umbrella term for different prediabetic states, each with distinct underlying pathophysiology. The limited data available question whether moderate weight loss is effective at preventing type 2 diabetes in each of the prediabetes subtypes.
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Effects of a Short-Term Recreational Team Handball-Based Programme on Physical Fitness and Cardiovascular and Metabolic Health of 33-55-Year-Old Men: A Pilot Study.
Póvoas, SCA, Castagna, C, Resende, C, Coelho, EF, Silva, P, Santos, R, Pereira, R, Krustrup, P
BioMed research international. 2018;:4109796
Abstract
Recreational team handball is an intermittent high-intensity exercise mode with physiological demands in the range of those found to enhance health and physical fitness of sedentary adults. We examined the effects of a short-term team handball-based training programme on physical fitness and metabolic and cardiovascular health of sedentary 33-55-year-old former male team handball players. Twenty-four participants were divided into team handball (THG; n=15) and control groups (CG; n=9) and evaluated at baseline and postintervention. During 12 weeks, THG performed 2-3 60-min recreational team handball matches weekly (average: 2.2 ± 0.7), and CG maintained an inactive lifestyle. Average heart rate (HR) during matches was 80 ± 7%HRmax, with peak values of 91 ± 6%HRmax. A time-by-group interaction was shown in aerobic performance (p=0.016), postural balance (p=0.019), maximum oxygen uptake (VO2max) (p=0.023), resting HR (p<0.001), high-density lipoprotein (HDL) cholesterol (p=0.048), and fasting blood glucose (p=0.052) in favor of THG. THG improved aerobic performance (80%, p<0.001), VO2max (14%, p<0.001), and postural balance (27%, p=0.018). Decreases in resting HR (16%, p<0.001) and fasting blood glucose (7%, p=0.015) and increases in HDL cholesterol (11%, p=0.002) were found in THG. Recreational team handball practice shows positive physical fitness and health-related adaptations, with high attendance, which may contribute to the reduction of the risk of developing lifestyle diseases.
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Ramadan model of intermittent fasting for 28 d had no major effect on body composition, glucose metabolism, or cognitive functions in healthy lean men.
Harder-Lauridsen, NM, Rosenberg, A, Benatti, FB, Damm, JA, Thomsen, C, Mortensen, EL, Pedersen, BK, Krogh-Madsen, R
Nutrition (Burbank, Los Angeles County, Calif.). 2017;:92-103
Abstract
OBJECTIVES There has been a parallel increase in the incidence of obesity and diabetes as well as the number of daily meals. However, evidence is lacking regarding the role of intermittent fasting. The aim of this study was to determine the effects of a Ramadan model of intermittent fasting (RIF; 14 h of daytime abstinence from food and drinking) for 28 d on body composition, glucose metabolism, and cognitive function. METHODS Ten healthy, lean men were included in a nonrandomized, crossover, intervention study. Testing was performed before a control period of 28 d, as well as before and after 28 d of RIF. Whole-body dual-energy x-ray absorptiometry, magnetic resonance imaging of the abdomen, fitness test, oral glucose tolerance test, and cognitive function tests were performed. As secondary outcome, the participants' physical activity and 72-h glycemic responses were monitored 6 d within each of the periods. Dietary intake, appetite, and mood questionnaires also were assessed. RESULTS Comparing Δ differences from testing days; body mass index changes from the control period (Δ mean: 0.2 kg/m2, 95% confidence interval [CI], -2 to 0.5) and the RIF period (Δ mean: -0.3 kg/m2, 95% CI, -0.6 to -0.1) were significantly different (P < 0.05). Secondary outcomes within the RIF period showed an increased area under curve (AUC) for hunger accompanied by a reduced AUC for satiety (both, P < 0.05), less mean steps per day (P < 0.05), and less positive feelings in the afternoon (P < 0.01) compared with the control period. No changes were observed in any of the other evaluated parameters. CONCLUSIONS Free-living participants were able to comply with 14 h of daily daytime abstinence from food and drinking for 28 d with only a minor effect on body mass index and without any effects on body composition, glucose metabolism, and cognitive function.