Insulin Management Strategies for Exercise in Diabetes

There is no question that regular exercise can be beneficial and lead to improvements in overall cardiovascular health. However, for patients with diabetes, exercise can also lead to challenges in maintaining blood glucose balance, particularly if patients are prescribed insulin or certain oral hypoglycemic agents. Hypoglycemia is the most common adverse event associated with exercise and insulin therapy, and the fear of hypoglycemia is also the greatest barrier to exercise for many patients. With the appropriate insulin dose adjustments and, in some cases, carbohydrate supplementation, blood glucose levels can be better managed during exercise and in recovery. In general, insulin strategies that help facilitate weight loss with regular exercise and recommendations around exercise adjustments to prevent hypoglycemia and hyperglycemia are often not discussed with patients because the recommendations can be complex and may differ from one individual to the next. This is a review of the current published literature on insulin dose adjustments and starting-point strategies for patients with diabetes in preparation for safe exercise.

Effects of fasted vs fed-state exercise on performance and post-exercise metabolism: A systematic review and meta-analysis

The effects of nutrition on exercise metabolism and performance remain an important topic among sports scientists, clinical, and athletic populations. Recently, fasted exercise has garnered interest as a beneficial stimulus which induces superior metabolic adaptations to fed exercise in key peripheral tissues. Conversely, pre-exercise feeding augments exercise performance compared with fasting conditions. Given these seemingly divergent effects on performance and metabolism, an appraisal of the literature is warranted. This review determined the effects of fasting vs pre-exercise feeding on continuous aerobic and anaerobic or intermittent exercise performance, and post-exercise metabolic adaptations. A search was performed using the MEDLINE and PubMed search engines. The literature search identified 46 studies meeting the relevant inclusion criteria. The Delphi list was used to assess study quality. A meta-analysis and meta-regression were performed where appropriate. Findings indicated that pre-exercise feeding enhanced prolonged (P = .012), but not shorter duration aerobic exercise performance (P = .687). Fasted exercise increased post-exercise circulating FFAs (P = .023) compared to fed exercise. It is evidenced that pre-exercise feeding blunted signaling in skeletal muscle and adipose tissue implicated in regulating components of metabolism, including mitochondrial adaptation and substrate utilization. This review's findings support the hypothesis that the fasted and fed conditions can divergently influence exercise metabolism and performance. Pre-exercise feeding bolsters prolonged aerobic performance, while seminal evidence highlights potential beneficial metabolic adaptations that fasted exercise may induce in peripheral tissues. However, further research is required to fully elucidate the acute and chronic physiological adaptations to fasted vs fed exercise.

Development and validation of a predictive model of acute glucose response to exercise in individuals with type 2 diabetes

BACKGROUND

Our purpose was to develop and test a predictive model of the acute glucose response to exercise in individuals with type 2 diabetes.

DESIGN AND METHODS

Data from three previous exercise studies (56 subjects, 488 exercise sessions) were combined and used as a development dataset. A mixed-effects Least Absolute Shrinkage Selection Operator (LASSO) was used to select predictors among 12 potential predictors. Tests of the relative importance of each predictor were conducted using the Lindemann Merenda and Gold (LMG) algorithm. Model structure was tested using likelihood ratio tests. Model accuracy in the development dataset was assessed by leave-one-out cross-validation.Prospectively captured data (47 individuals, 436 sessions) was used as a test dataset. Model accuracy was calculated as the percentage of predictions within measurement error. Overall model utility was assessed as the number of subjects with ≤1 model error after the third exercise session. Model accuracy across individuals was assessed graphically. In a post-hoc analysis, a mixed-effects logistic regression tested the association of individuals' attributes with model error.

RESULTS

Minutes since eating, a non-linear transformation of minutes since eating, post-prandial state, hemoglobin A1c, sulfonylurea status, age, and exercise session number were identified as novel predictors. Minutes since eating, its transformations, and hemoglobin A1c combined to account for 19.6% of the variance in glucose response. Sulfonylurea status, age, and exercise session each accounted for <1.0% of the variance. In the development dataset, a model with random slopes for pre-exercise glucose improved fit over a model with random intercepts only (likelihood ratio 34.5, p < 0.001). Cross-validated model accuracy was 83.3%.In the test dataset, overall accuracy was 80.2%. The model was more accurate in pre-prandial than postprandial exercise (83.6% vs. 74.5% accuracy respectively). 31/47 subjects had ≤1 model error after the third exercise session. Model error varied across individuals and was weakly associated with within-subject variability in pre-exercise glucose (Odds ratio 1.49, 95% Confidence interval 1.23-1.75).

CONCLUSIONS

The preliminary development and test of a predictive model of acute glucose response to exercise is presented. Further work to improve this model is discussed.

The beta-1 adrenergic antagonist, atenolol, decreases acylation stimulating protein, exercise capacity and plasma free fatty acids in men with type 2 diabetes

BACKGROUND AND AIMS

Atenolol is a beta-1 adrenergic antagonist commonly prescribed for the treatment of systemic hypertension or coronary artery disease yet its use in individuals with type 2 diabetes mellitus (T2DM) is controversial due to potentially negative side effects on insulin resistance. Non-esterified fatty acid (NEFA) metabolism is altered in T2DM especially under conditions of metabolic stress such as exercise or the postprandial state. We evaluated atenolol effects on circulating NEFA and related hormones in men with T2DM during acute cardiorespiratory exercise in both the fasting and postprandial state, including the adipokine acylation stimulating protein (ASP) which stimulates adipose tissue NEFA uptake.

METHODS AND RESULTS

Ten men with T2DM underwent four 1-h exercise sessions at 60% of their maximal oxygen uptake (VO(2max)) under the following conditions: 1) fasting (F), and 2) 2 h postprandial (PP) without medication; and 3) fasting (F-Atenolol), and 4) 2 h postprandial (PP-Atenolol) after a one-week treatment with atenolol. Results were tested for the effects of atenolol via two-way ANOVA for the F vs F-Atenolol and PP vs PP-Atenolol states separately. Atenolol treatment decreased fasting and postprandial glycerol (p < 0.0001) and NEFA (p < 0.0001), postprandial epinephrine (p = 0.048), postprandial cortisol (p = 0.02), postprandial ASP (p = 0.04) and postprandial dopamine (p < 0.004).

CONCLUSION

Atenolol alters fatty acid metabolism and associated metabolic hormones including ASP during exercise in men with T2DM and its effects are more apparent during conditions of stress such as the postprandial state, acute exercise and obesity.

The effectiveness of physical leisure time activities on glycaemic control in adult patients with diabetes type 2: A Systematic Review

REVIEW QUESTION/OBJECTIVE

The objective of this systematic review is to synthesise the best available evidence on the effectiveness of physical leisure time activities on glycaemic control in adult patients with diabetes type 2.The specific review question is:What is the effectiveness of physical leisure time activities on glycaemic control in patients with diabetes type 2?

BACKGROUND

Type 2 diabetes results from the body's ineffective use of insulin. Diabetes is a group of diseases marked by high levels of blood glucose resulting from defects in insulin production, insulin action, or both.Type 2 diabetes was previously called non-insulin-dependent diabetes mellitus (NIDDM) or adult-onset diabetes. According to 2011 National Diabetes Fact Sheet, diabetes affected 25.8 million people of all ages of United States population during 2005-2008, include 18.8 million diagnosed people and seven million undiagnosed people. Among United States residents ages 65 years and older, 10.9 million, or 26.9 percent, had diabetes in 2010. Recent World Health Organization (WHO) calculations indicate diabetes kills more than one million people annually, almost 80% of which occur in low- and middle-income countries. Almost half of diabetes deaths occur in people aged under 70 years; 55% of diabetes deaths are in women. WHO projects that diabetes deaths will double between 2005 and 2030.Type 2 diabetes is associated with older age, obesity, family history of diabetes, history of gestational diabetes, impaired glucose metabolism, physical inactivity, and race. It is a common outcome of uncontrolled blood sugar and over time leads to serious complications including hypertension, blindness, kidney damage, lower-limb amputations, heart disease, and stroke. Good glycaemic control is a major goal in the treatment of type 2 diabetes mellitus to prevent and delay those severe long-term complications. Physical activity is considered to be a substantial part of the treatment of type 2 diabetes mellitus, as well as diet and medication. Physical activity is a common physiological stressor that causes perturbation to glucose homeostasis and energy needs.Several studies have reported the effects of physical activity on improving insulin sensitivity, cardio-respiratory fitness, glycaemic control, and psychosocial well-being. The American Diabetes Association suggests that people with type 2 diabetes spend at least 150 minutes a week on moderate-intensity physical activity (50-70% of maximum heart rate), or at least 90 minutes a week on vigorous physical activity (>70% of maximum heart rate). Recent studies also indicate that moderate-intensity aerobic physical activity could help type 2 diabetes patients to maintain ideal glycaemic control. Boule et al found physical activity training could reduce haemoglobin A1c (HbA1c) (control group vs. exercise group: 8.31% vs. 7.65%) by 0.66%. This is close to the effect of intense glucose-lowering pharmacological treatment found in the United Kingdom Prospective Diabetes Study. A 1% absolute decrease in the HbA1c value is associated with a 15% to 20% decrease in major cardiovascular events and a 37% reduction in microvascular complications.According to Zhao, Ford, Chaoyang's report (2011), only 25-42% of older adults with diabetes mellitus met recommendations for total physical activity based on the 2007 American Diabetes Association and 2008 Department of Health and Human Services guidelines. Various barriers to regular physical activity had been described, such as health problems, lack of time or energy, no exercise partner, lack of family support, and motivation and working time. An active lifestyle does not require complex exercise programmes. Instead, regular daily physical activity is believed to enable individuals to reduce the risk of chronic diseases and may enhance their quality of life. Recently, it has been thought that, instead of structured physical activity, lifestyle physical activity is a better alternative for diabetes patients. Moderate or vigorous lifestyle or leisure time physical activities included jogging, walking, gardening, tai chi chuan, and qigong (an ancient Chinese breathing exercise that combines aerobics, isometric and isotonic movements and meditation). According to data from recent studies, moderate physical leisure time activities for at least 60 minutes every week can effectively improve glycaemic control in patients with diabetes type 2.Those measure indicators of glycaemic control including glycated hemoglobin A1c (HbA1c), fasting plasma glucose (FPG), and postprandial plasma glucose (PPG) were used to assess glycaemic control in diabetic patients. HbA1c value reflects the mean plasma glucose concentration over two to three months. Fasting plasma glucose (FPG) and postprandial plasma glucose (PPG) reflect short-term plasma glucose change. Glycated haemoglobin is a form ofhaemoglobin that is measured primarily to identify the averageplasmaglucoseconcentration over prolonged periods of time. The fasting plasma glucose test measures fasting blood sugar levels and the postprandial plasma glucose test is often used to test the effectiveness of the body's carbohydrate metabolism and the ability to produce insulin. In 2010, Psaltopoulou et al gathered current information from meta-analyses on dietary and lifestyle practices concerning reduction of risk to develop type 2 diabetes. In 2009, Thomas et al completed a systematic review in which fourteen randomised controlled trials involving a total of 377 participants comparing exercise against no exercise in type 2 diabetes were identified. Trials ranged from eight weeks to twelve months duration. Compared with the control, the exercise intervention significantly improved glycaemic control as indicated by a decrease in glycated haemoglobin levels of 0.6%. This systematic review will differ from these two previously published reviews in that it aims to explore the effectiveness of different kinds of moderate or vigorous physical leisure time activities in improving glycaemic control in patients with diabetes type 2. A search of MEDLINE, DARE database, CINAHL, the Cochrane Library of Systematic Reviews and Joanna Briggs Institute Library of Systematic Reviews found no existing reviews or review underway on this topic.