Physical Activity/Exercise and Diabetes: A Position Statement of the American Diabetes Association

Glycemic Control and Muscle Damage in 3 Athletes With Type 1 Diabetes During a Successful Performance in a Relay Ultramarathon: A Case Report

Ultramarathon races are fairly demanding and impose substantial physiological stress on healthy athletes. These competitions may thus be considerably more challenging for individuals with diabetes. This case study aims to describe glycemic control, muscle damage, inflammation, and renal function in 3 athletes with type 1 diabetes during a successful performance in a relay ultramarathon. The team completed the race in 29 hours and 28 minutes, earning third place. The total distance covered by each athlete was 68.7, 84.5, and 65.1 km. Most blood glucose levels showed that athletes were in a zone where it was safe to exercise (90-250 mg/dL or 5.0-13.9 mmol/L). Creatine kinase, lactate dehydrogenase, and aspartate aminotransferase serum levels increased 1.2- to 50.7-fold prerace to postrace, and were higher than the reference ranges for all the athletes postrace. Blood leukocytes, neutrophils, and serum C-reactive protein (CRP) increased 1.6- to 52-fold prerace to postrace and were higher than the reference ranges for 2 athletes after the race. Serum creatinine increased 1.2-fold prerace to postrace for all the athletes but did not meet the risk criteria for acute kidney injury. In conclusion, our main findings show evidence of satisfactory glycemic control in athletes with type 1 diabetes during a relay ultramarathon. Moreover, elevation of muscle damage and inflammatory biomarkers occurred without affecting renal function and challenging the maintenance of blood glucose among athletes. These findings are novel and provide an initial understanding of the physiological responses in athletes with type 1 diabetes during ultramarathon races.

Patient and practitioner perspectives on reducing sedentary behavior at an exercise-based cardiac rehabilitation program

PURPOSE

To understand the awareness of sedentary behavior, as well as the perceived facilitators and barriers to reducing sedentary behaviors from the perspectives of patients undertaking an exercise-based cardiac rehabilitation program, and from staff involved in supporting patient self-management.

MATERIALS AND METHODS

A qualitative study was conducted at a large cardiac rehabilitation program in a metropolitan city in Canada. Guided by an ecological framework, semi-structured interviews were conducted individually with 15 patients, and in two focus groups with six staff. Transcribed interviews were analyzed by thematic analysis.

RESULTS

Patients placed little importance on reducing sedentary behavior as they were unconvinced of the health benefits, did not perceive themselves to be sedentary, or associated such behaviors with enjoyment and relaxation. While staff were aware of the risks, they saw them as less critical than other health behaviors. Intrapersonal factors (physical and psychosocial health) and environment factors (the information environment, socio-cultural factors) within leisure time, the home, and work, influenced sedentary behavior.

CONCLUSIONS

While these findings require further testing, future interventions may be effective if aimed at increasing awareness of the health benefits of reducing sedentary behavior, utilizing existing behavior change strategies, and using a participatory approach to tailor strategies to patients. Implications for rehabilitation Cardiac rehabilitation programs effectively use exercise promotion to improve the health of people with established cardiovascular disease. As sedentary lifestyles become more prevalent, recommendations to reduce the health risks of prolonged sedentary behavior that are specific to the characteristics and prognostic profiles of cardiac rehabilitation patients are needed. Cardiac rehabilitation programs must consider extending existing behavior change strategies utilized for exercise promotion towards addressing sedentary behaviors in order to be effective at reducing the sedentary time of patients. A participatory approach involving both patients and health professionals can support patients in reducing their sedentary behavior by providing a supportive environment for behavior change, increasing awareness and understanding of risks, discussing the feasibility of potential strategies, and setting achievable and actionable goals.

The Effects of Basal Insulin Suspension at the Start of Exercise on Blood Glucose Levels During Continuous Versus Circuit-Based Exercise in Individuals with Type 1 Diabetes on Continuous Subcutaneous Insulin Infusion

BACKGROUND

Exercise causes glycemic disturbances in individuals with type 1 diabetes (T1D). Continuous moderate-intensity aerobic exercise (CON) generally lowers blood glucose (BG) levels and often leads to hypoglycemia. In comparison, circuit-based exercise (CIRC) may attenuate the drop in BG. The goal of this study is to contrast the effects of basal insulin suspension at the onset of two different forms of exercise (CON vs. CIRC).

METHODS

Twelve individuals (six men and six women) with T1D on insulin pump therapy were recruited for the study. All participants completed a maximal aerobic fitness test and two 40-min exercise sessions, consisting of either continuous treadmill walking or a circuit workout. Basal insulin infusion was stopped at the onset of exercise and resumed in recovery. After providing an initial reference value, volunteers were blinded to their [BG] and were asked to estimate their levels during exercise.

RESULTS

Oxygen consumption (47.5 ± 7.5 vs. 54.5 ± 13.5 mL·kg^-1·min^-1, P = 0.03) and heart rate (122 ± 20 vs. 144 ± 20 bpm, P = 0.003) were lower in CON vs. CIRC. Despite the lower workload, BG levels dropped more with CON vs. CIRC (delta BG = -3.8 ± 1.5 vs. -0.5 ± 3.0 mmol/L for CON vs. CIRC, respectively, P = 0.001). Participants were able to estimate their BG more accurately during CON (r = 0.83) vs. CIRC (r = 0.33) based on a regression analysis.

CONCLUSION

Despite a lower intensity of exercise, with full basal insulin suspension at the start of exercise, CON results in a larger drop in BG vs. CIRC. These findings have implications for single hormone-based artificial pancreas development for exercise. While this study does not negate the importance of frequent capillary BG monitoring during exercise, it does suggest that if persons are knowledgeable about their pre-exercise BG levels, they can accurately perceive the changes in BG during CON, but not during CIRC.

Outpatient Closed-Loop Control with Unannounced Moderate Exercise in Adolescents Using Zone Model Predictive Control

BACKGROUND

The artificial pancreas (AP) has the potential to improve glycemic control in adolescents. This article presents the first evaluation in adolescents of the Zone Model Predictive Control and Health Monitoring System (ZMPC+HMS) AP algorithms, and their first evaluation in a supervised outpatient setting with frequent exercise.

MATERIALS AND METHODS

Adolescents with type 1 diabetes underwent 3 days of closed-loop control (CLC) in a hotel setting with the ZMPC+HMS algorithms on the Diabetes Assistant platform. Subjects engaged in twice-daily exercise, including soccer, tennis, and bicycling. Meal size (unrestricted) was estimated and entered into the system by subjects to trigger a bolus, but exercise was not announced.

RESULTS

Ten adolescents (11.9-17.7 years) completed 72 h of CLC, with data on 95 ± 14 h of sensor-augmented pump (SAP) therapy before CLC as a comparison to usual therapy. The percentage of time with continuous glucose monitor (CGM) 70-180 mg/dL was 71% ± 10% during CLC, compared to 57% ± 16% during SAP (P = 0.012). Nocturnal control during CLC was safe, with 0% (0%, 0.6%) of time with CGM <70 mg/dL compared to 1.1% (0.0%, 14%) during SAP. Despite large meals (estimated up to 120 g carbohydrate), only 8.0% ± 6.9% of time during CLC was spent with CGM >250 mg/dL (16% ± 14% during SAP). The system remained connected in CLC for 97% ± 2% of the total study time. No adverse events or severe hypoglycemia occurred.

CONCLUSIONS

The use of the ZMPC+HMS algorithms is feasible in the adolescent outpatient environment and achieved significantly more time in the desired glycemic range than SAP in the face of unannounced exercise and large announced meal challenges.

Physical inactivity and sedentary behavior: Overlooked risk factors in autoimmune rheumatic diseases?

This review aims to (1) summarize the estimates of physical inactivity and sedentary behavior in autoimmune rheumatic diseases; (2) describe the relationship between physical (in)activity levels and disease-related outcomes; (3) contextualize the estimates and impact of physical inactivity and sedentary behavior in autoimmune diseases compared to other rheumatic diseases and chronic conditions; and (4) discuss scientific perspectives around this theme and potential clinical interventions to attenuate these preventable risk factors. We compiled evidence to show that estimates of physical inactivity and sedentary behavior in autoimmune rheumatic diseases are generally comparable to other rheumatic diseases as well as to other chronic conditions (e.g., type 2 diabetes, cardiovascular diseases, and obesity), in which a lack of physical activity and excess of sedentary behavior are well-known predictors of morbimortality. In addition, we also showed evidence that both physical inactivity and sedentary behavior may be associated with poor health-related outcomes (e.g., worse disease symptoms and low functionality) in autoimmune rheumatic diseases. Thus, putting into practice interventions to make the patients "sit less and move more", particularly light-intensity activities and/or breaking-up sedentary time, is a simple and prudent therapeutic approach to minimize physical inactivity and sedentary behavior, which are overlooked yet modifiable risk factors in the field of autoimmune rheumatic diseases.

Exercise management in type 1 diabetes: a consensus statement

Type 1 diabetes is a challenging condition to manage for various physiological and behavioural reasons. Regular exercise is important, but management of different forms of physical activity is particularly difficult for both the individual with type 1 diabetes and the health-care provider. People with type 1 diabetes tend to be at least as inactive as the general population, with a large percentage of individuals not maintaining a healthy body mass nor achieving the minimum amount of moderate to vigorous aerobic activity per week. Regular exercise can improve health and wellbeing, and can help individuals to achieve their target lipid profile, body composition, and fitness and glycaemic goals. However, several additional barriers to exercise can exist for a person with diabetes, including fear of hypoglycaemia, loss of glycaemic control, and inadequate knowledge around exercise management. This Review provides an up-to-date consensus on exercise management for individuals with type 1 diabetes who exercise regularly, including glucose targets for safe and effective exercise, and nutritional and insulin dose adjustments to protect against exercise-related glucose excursions.

A pilot study of short-term toe resistance training in patients with type 2 diabetes mellitus

Objective

The purpose of this pilot study was to investigate the effect of short-term toe resistance training on toe pinch force and toe muscle quality in patients with type 2 diabetes mellitus.

Methods

A total of 12 patients with type 2 diabetes mellitus who were hospitalized to improve glycemic control (8 men and 4 women, duration of diabetes 12.2 ± 9.5 years) were enrolled in this pilot study. Exercise therapy was performed with conventional aerobic exercise and four newly developed toe resistance training exercises for 2 weeks. Changes in anthropometric parameters, blood pressure (BP), heart rate, and muscle parameters, i.e. muscle mass, toe pinch force and toe muscle quality were evaluated after the exercise program.

Results

There were no significant differences of body weight, body mass index, BP, heart rate, and upper/lower muscle mass after exercise performance. However, toe pinch force was significantly increased (pre: 2.92 ± 1.19 kg, post: 3.65 ± 1.58 kg, p = 0.007). Toe muscle quality (toe pinch force/lower leg muscle mass) were also significantly increased (pre: 2.15 ± 0.86 kg/kg, post: 2.72 ± 1.26 kg/kg, p = 0.009).

Conclusions

Two weeks of toe resistance training significantly increased toe pinch force and toe muscle quality in patients with type 2 diabetes mellitus. Toe resistance training is might be essential for treating patients with diabetes mellitus in clinical practice.

Resistance training to improve type 2 diabetes: working toward a prescription for the future

The prevalence of type 2 diabetes (T2D) is rapidly increasing, and effective strategies to manage and prevent this disease are urgently needed. Resistance training (RT) promotes health benefits through increased skeletal muscle mass and qualitative adaptations, such as enhanced glucose transport and mitochondrial oxidative capacity. In particular, mitochondrial adaptations triggered by RT provide evidence for this type of exercise as a feasible lifestyle recommendation to combat T2D, a disease typically characterized by altered muscle mitochondrial function. Recently, the synergistic and antagonistic effects of combined training and Metformin use have come into question and warrant more in-depth prospective investigations. In the future, clinical intervention studies should elucidate the mechanisms driving RT-mitigated mitochondrial adaptations in muscle and their link to improvements in glycemic control, cholesterol metabolism and other cardiovascular disease risk factors in individuals with T2D.

Epidemiology in diabetes mellitus and cardiovascular disease

As one of the leading causes of death in the USA, diabetes mellitus (DM) has become an epidemic over the past few decades. Despite the high prevalence of diagnosed DM, close to half of all people with DM are unaware of their disease. The risk of type 2 DM is determined by interplay of genetic and metabolic factors. Patients with type 2 DM have a higher risk of death from cardiovascular causes compared with their nondiabetic counterparts, and the mortality rate of DM associated cardiovascular disease is different among ethnicity groups and sex groups. Because of its adverse effect on people's health, DM also imposes an economic burden on individuals and households affected, as well as on the healthcare system. Current guidelines for cardiovascular disease prevention have focused on lifestyle management, blood pressure control, lipid control, blood glucose control, antiplatelet agent use, and tobacco use cessation.

Adding exercise or subtracting sitting time for glycaemic control: where do we stand?

While regular structured exercise is a well-established (though arguably under-utilised) cornerstone in the prevention and management of type 2 diabetes, population adherence to recommended exercise guidelines remains stubbornly low. Indeed, most adults are exposed to environmental settings (at work, in automobile travel and in the domestic environment) that may not only limit their physical activity, but also promote sitting for prolonged periods of time. However, recent experimental evidence indicates that reducing and breaking up sitting time may also be a useful strategy to improve glycaemic control. In this issue of Diabetologia, Duvivier and colleagues report findings which suggest that reducing sitting time with standing and light-intensity activity could be a potential alternative to structured exercise for improving glycaemic control in type 2 diabetes patients. We review and discuss the findings of this study, its potential clinical implications, and a number of knowledge gaps and opportunities that could be considered in the interest of future research. The findings from Duvivier and colleagues should encourage healthcare practitioners, researchers and type 2 diabetes patients to consider the whole spectrum of physical activity, from sedentary behaviour through to structured exercise.

Glycemic and Metabolic Effects of Two Long Bouts of Moderate-Intensity Exercise in Men with Normal Glucose Tolerance or Type 2 Diabetes

BACKGROUND

The glycemic and insulinemic responses following 30-60 min of exercise have been extensively studied, and a dose-response has been proposed between exercise duration, or volume, and improvements in glucose tolerance or insulin sensitivity. However, few studies have examined the effects of longer bouts of exercise in type 2 diabetes (T2D). Longer bouts may have a greater potential to affect glucagon, interleukin-6 (IL-6) and incretin hormones [i.e., glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic peptide (GIP)].

AIM

To examine the effect of two bouts of long-duration, moderate-intensity exercise on incretins, glucagon, and IL-6 responses before and after exercise, as well as in response to an oral glucose tolerance test (OGTT) conducted the following day.

METHODS

Twelve men, six with and six without T2D, participated in two separate conditions (i.e., exercise vs. rest) according to a randomized crossover design. On day 1, participants either rested or performed two 90 min bouts of treadmill exercise (separated by 3.5 h) at 80% of their ventilatory threshold. All participants received standardized meals on day 1. On day 2 of each condition, glucose and hormonal responses were measured during a 4-h OGTT.

RESULTS

On day 1, exercise increased IL-6 at the end of the first bout of exercise (exercise by time interaction p = 0.03) and GIP overall (main effect of exercise p = 0.004). Glucose was reduced to a greater extent in T2D following exercise (exercise by T2D interaction p = 0.03). On day 2, GIP and active GLP-1 were increased in the fasting state (p = 0.05 and p = 0.03, respectively), while plasma insulin and glucagon concentrations were reduced during the OGTT (p = 0.01 and p = 0.02, respectively) in the exercise compared to the rest condition for both healthy controls and T2D. Postprandial glucose was elevated in T2D compared to healthy control (p < 0.05) but was not affected by exercise.

CONCLUSION

Long-duration, moderate-intensity aerobic exercise can increase IL-6. On the day following exercise, fasting incretins remained increased but postprandial insulin and glucagon were decreased without affecting postprandial glucose. This long duration of exercise may not be appropriate for some people, and further research should investigate why next day glucose tolerance was unchanged.

The Potential Role of Contraction-Induced Myokines in the Regulation of Metabolic Function for the Prevention and Treatment of Type 2 Diabetes

Skeletal muscle represents the largest organ in the body, comprises 36-42% of body weight, and has recently been recognized as having an endocrine function. Proteins expressed and released by muscle that have autocrine, paracrine, and endocrine bioactivities have been termed myokines. It is likely that muscle contraction represents the primary stimulus for the synthesis and secretion of myokines to enable communication with other organs such as the liver, adipose tissue, brain, and auto-regulation of muscle metabolism. To date, several hundred myokines in the muscle secretome have been identified, a sub-population of which are specifically induced by skeletal muscle contraction. However, the bioactivity of many of these myokines and the mechanism through which they act has either not yet been characterized or remains poorly understood. Physical activity and exercise are recognized as a central tenet in both the prevention and treatment of type 2 diabetes (T2D). Recent data suggest humoral factors such as muscle-derived secretory proteins may mediate the beneficial effects of exercise in the treatment of metabolic diseases. This mini-review aims to summarize our current knowledge on the role of contraction-induced myokines in mediating the beneficial effects of physical activity and exercise in the prevention and treatment of T2D, specifically glucose and lipid metabolism. Future directions as to how we can optimize contraction-induced myokine secretion to inform exercise protocols for the prevention and treatment of T2D will also be discussed.

In vitro killing of schistosomula of Schistosoma mansoni by BCG and C. parvum-activated macrophages

Resistance to Schistosoma mansoni infection in the mouse has been induced either specifically by a primary infection with this parasite or nonspecifically by a variety of immunostimulants such as BCG. In the present study we developed an in vitro system to examine the effector mechanism of nonspecifically induced resistance. Activated macrophage monolayers obtained from BCG- or Corynebacterium parvum treated mice killed a respective mean 32 +/- 6% and 48 +/- 5% of schistosomula after 24 hr incubation. The killing of the parasites was verified by their inability to mature to adult worms upon injection into normal mice. The activated macrophage-mediated killing was related to cell:parasite ratio, and was partially lost if the macrophage monolayers were kept in cultures for 24 hr before incubation with the organism. Supernatants of macrophages cultured in the presence of schistosomula killed a mean of 51 +/- 3% of the organisms whereas those from cells cultured alone resulted in a mean killing of 25 +/- 3%. Furthermore, toxic supernatants could be generated equally well on incubation with S. mansoni schistosomula or Trichinella spiralis larvae. Our data show that activated macrophage monolayers through soluble mediators destroy a significant proportion of the multicellular parasite S. mansoni schistosomula in vitro.