Insulin-based strategies to prevent hypoglycaemia during and after exercise in adult patients with type 1 diabetes on pump therapy: the DIABRASPORT randomized study

Modifiable self-management practices impact nocturnal and morning glycaemia in type 1 diabetes

AIMS

To identify risk factors for nocturnal/morning hypo- and hyperglycaemia in type 1 diabetes.

METHODS

Data on self-management practices were obtained from 3-day records. We studied the associations between self-management practices on the first recording day and the self-reported blood glucose (BG) concentrations on the subsequent night/morning.

RESULTS

Of the 1025 participants (39 % men, median age 45 years), 4.4 % reported nocturnal hypoglycaemia (<3.9 mmol/l), 9.8 % morning hypoglycaemia, 51.5 % morning euglycaemia, and 34.3 % morning hyperglycaemia (≥8.9 mmol/l). Within hypoglycaemic range, insulin pump use was associated with higher nocturnal BG concentration (B=0.486 [95 % Confidence Interval=0.121-0.852], p=0.009). HbA1c was positively (0.046 [0.028-0.065], p<0.001), while antecedent fibre intake (-0.327 [-0.543 - -0.111], p=0.003) and physical activity (PA) (-0.042 [-0.075 - -0.010], p=0.010) were inversely associated with morning BG concentration. The odds of morning hypoglycaemia were increased by previous day hypoglycaemia (OR=2.058, p=0.002) and alcohol intake (1.031, p=0.001). Previous day PA (0.977, p=0.031) and fibre intake (0.848, p=0.017) were inversely, while HbA1c (1.027, p<0.001) was positively associated with the risk of morning hyperglycaemia.

CONCLUSIONS

Alcohol avoidance may prevent nocturnal hypoglycaemia, while PA and fibre intake may reduce hyperglycaemia risk. Avoidance of daytime hypoglycaemia and keeping HbA1c in control may help maintain normoglycaemia also at night-time.

Postprandial glucose-management strategies in type 1 diabetes: Current approaches and prospects with precision medicine and artificial intelligence

Postprandial glucose control can be challenging for individuals with type 1 diabetes, and this can be attributed to many factors, including suboptimal therapy parameters (carbohydrate ratios, correction factors, basal doses) because of physiological changes, meal macronutrients and engagement in postprandial physical activity. This narrative review aims to examine the current postprandial glucose-management strategies tested in clinical trials, including adjusting therapy settings, bolusing for meal macronutrients, adjusting pre-exercise and postexercise meal boluses for postprandial physical activity, and other therapeutic options, for individuals on open-loop and closed-loop therapies. Then we discuss their challenges and future avenues. Despite advancements in insulin delivery devices such as closed-loop systems and decision-support systems, many individuals with type 1 diabetes still struggle to manage their glucose levels. The main challenge is the lack of personalized recommendations, causing suboptimal postprandial glucose control. We suggest that postprandial glucose control can be improved by (i) providing personalized recommendations for meal macronutrients and postprandial activity; (ii) including behavioural recommendations; (iii) using other personalized therapeutic approaches (e.g. glucagon-like peptide-1 receptor agonists, sodium-glucose co-transporter inhibitors, amylin analogues, inhaled insulin) in addition to insulin therapy; and (iv) integrating an interpretability report to explain to individuals about changes in treatment therapy and behavioural recommendations. In addition, we suggest a future avenue to implement precision recommendations for individuals with type 1 diabetes utilizing the potential of deep reinforcement learning and foundation models (such as GPT and BERT), employing different modalities of data including diabetes-related and external background factors (i.e. behavioural, environmental, biological and abnormal events).

A Nutritional Approach to Optimizing Pump Therapy in Type 1 Diabetes Mellitus

Achieving optimal glucose control in individuals with type 1 diabetes (T1DM) continues to pose a significant challenge. While continuous insulin infusion systems have shown promise as an alternative to conventional insulin therapy, there remains a crucial need for greater awareness regarding the necessary adaptations for various special circumstances. Nutritional choices play an essential role in the efficacy of diabetes management and overall health status for patients with T1DM. Factors such as effective carbohydrate counting, assessment of the macronutrient composition of meals, and comprehending the concept of the glycemic index of foods are paramount in making informed pre-meal adjustments when utilizing insulin pumps. Furthermore, the ability to handle such situations as physical exercise, illness, pregnancy, and lactation by making appropriate adjustments in nutrition and pump settings should be cultivated within the patient-practitioner relationship. This review aims to provide healthcare practitioners with practical guidance on optimizing care for individuals living with T1DM. It includes recommendations on carbohydrate counting, managing mixed meals and the glycemic index, addressing exercise-related challenges, coping with illness, and managing nutritional needs during pregnancy and lactation. Additionally, considerations relating to closed-loop systems with regard to nutrition are addressed. By implementing these strategies, healthcare providers can better equip themselves to support individuals with T1DM in achieving improved diabetes management and enhanced quality of life.

Where to Start? Physical Assessment, Readiness, and Exercise Recommendations for People With Type 1 or Type 2 Diabetes

Exercise plays an important role in the management of diabetes and is associated with many benefits such as decreased morbidity and mortality. For people exhibiting signs and symptoms of cardiovascular disease, pre-exercise medical clearance is warranted; however, requiring broad screening requirements can lead to unnecessary barriers to initiating an exercise program. Robust evidence supports the promotion of both aerobic and resistance training, with evidence emerging on the importance of reducing sedentary time. For people with type 1 diabetes, there are special considerations, including hypoglycemia risk and prevention, exercise timing (including prandial status), and differences in glycemic responses based on biological sex.

Exercise in adults with type 1 diabetes mellitus

Regular physical activity improves cardiometabolic and musculoskeletal health, helps with weight management, improves cognitive and psychosocial functioning, and is associated with reduced mortality related to cancer and diabetes mellitus. However, turnover rates of glucose in the blood increase dramatically during exercise, which often results in either hypoglycaemia or hyperglycaemia as well as increased glycaemic variability in individuals with type 1 diabetes mellitus (T1DM). A complex neuroendocrine response to an acute exercise session helps to maintain circulating levels of glucose in a fairly tight range in healthy individuals, while several abnormal physiological processes and limitations of insulin therapy limit the capacity of people with T1DM to exercise in a normoglycaemic state. Knowledge of the acute and chronic effects of exercise and regular physical activity is critical for the formulation of clinical strategies for the management of insulin and nutrition for active patients with T1DM. Emerging diabetes-related technologies, such as continuous glucose monitors, automated insulin delivery systems and the administration of solubilized glucagon, are demonstrating efficacy for preserving glucose homeostasis during and after exercise in this population of patients. This Review highlights the beneficial effects of regular exercise and details the complex endocrine and metabolic responses to different types of exercise for adults with T1DM. An overview of basic clinical strategies for the preservation of glucose homeostasis using emerging technologies is also provided.

Association of HbA1c with VO2max in Individuals with Type 1 Diabetes: A Systematic Review and Meta-Analysis

The aim of this systematic review and meta-analysis was to evaluate the association between glycemic control (HbA1c) and functional capacity (VO2max) in individuals with type 1 diabetes (T1DM). A systematic literature search was conducted in EMBASE, PubMed, Cochrane Central Register of Controlled Trials, and ISI Web of Knowledge for publications from January 1950 until July 2020. Randomized and observational controlled trials with a minimum number of three participants were included if cardio-pulmonary exercise tests to determine VO2max and HbA1c measurement has been performed. Pooled mean values were estimated for VO2max and HbA1c and weighted Pearson correlation and meta-regression were performed to assess the association between these parameters. We included 187 studies with a total of 3278 individuals with T1DM. The pooled mean HbA1c value was 8.1% (95%CI; 7.9−8.3%), and relative VO2max was 38.5 mL/min/kg (37.3−39.6). The pooled mean VO2max was significantly lower (36.9 vs. 40.7, p = 0.001) in studies reporting a mean HbA1c > 7.5% compared to studies with a mean HbA1c ≤ 7.5%. Weighted Pearson correlation coefficient was r = −0.19 (p < 0.001) between VO2max and HbA1c. Meta-regression adjusted for age and sex showed a significant decrease of −0.94 mL/min/kg in VO2max per HbA1c increase of 1% (p = 0.024). In conclusion, we were able to determine a statistically significant correlation between HbA1c and VO2max in individuals with T1DM. However, as the correlation was only weak, the association of HbA1c and VO2max might not be of clinical relevance in individuals with T1DM.

Anticipated Basal Insulin Reduction to Prevent Exercise-Induced Hypoglycemia in Adults and Adolescents Living with Type 1 Diabetes

Objective: We investigated the effect of two key timings for basal insulin rate reduction on exercise-induced glucose changes and explored the association between circulating insulin concentrations and muscle vasoreactivity. Research Design and Methods: Twenty adults and adolescents performed 60-min exercise sessions (ergocycle) at 60% VO_2peak, 240 min after a standardized lunch. In a randomized order, we compared an 80% basal insulin reduction applied 40 min (T-40) or 90 min (T-90) before exercise onset. Near-infrared spectroscopy was used to investigate muscle hemodynamics at vastus lateralis. Glucose and insulin plasma concentrations were measured. Results: Reduction in plasma glucose (PG) level during exercise was attenuated during T-90 versus T-40 strategy (-0.89 ± 1.89 mmol/L vs. -2.17 ± 2.49 mmol/L, respectively; P = 0.09). Linear mixed model analysis showed that PG dropped by an additional 0.01 mM per minute in T-40 versus T-90 (time × strategy interaction, P < 0.05). The absolute number of hypoglycemic events was not different between the two strategies, but they occurred later with T-90. Free insulin tends to decrease more during the pre-exercise period in the T-90 strategy (P = 0.08). Although local muscle vasodilatation (ΔTHb) was comparable between the two strategies, we found that PG dropped more in cases of higher exercise-induced skeletal muscle vasodilatation (ΔTHb × time interaction P < 0.005, e: -0.0086 mM/min and additional mM of ΔTHb). Conclusion: T-90 timing reduced exercise-induced drop in PG and delayed the occurrence of hypoglycemic episodes compared with T-40 timing without a significant reduction in the number of events requiring treatment. Trial registration: ClinicalTrials.gov identifier: NCT03349489.

Considerations in the Care of Athletes With Type 1 Diabetes Mellitus

Type 1 diabetes mellitus is an autoimmune disease caused by affected individuals’ autoimmune response to their own pancreatic beta-cell. It affects millions of people worldwide. Exercise has numerous health and social benefits for patients with type 1 diabetes mellitus; however, careful management of blood glucose is crucial to minimize the risk of hypoglycemia and hyperglycemia. Anaerobic and aerobic exercises cause different glycemic responses during and after exercise, each of which will affect athletes’ ability to reach their target blood glucose ranges. The optimization of the patient’s macronutrient consumption, especially carbohydrates, the dosage of basal and short-acting insulin, and the frequent monitoring of blood glucose, will enable athletes to perform at peak levels while reducing their risk of dysglycemia. Despite best efforts, hypoglycemia can occur. Recognition of symptoms and rapid treatment with either fast-acting carbohydrates or glucagon is important. Continuous glucose monitoring devices have become more widely used in preventing hypoglycemia.

Prevention of exercise-induced hypoglycemia in 12 patients with type 1 diabetes running the Paris Marathon using continuous glucose monitoring: a prospective, single-center observational study

OBJECTIVE

To investigate the glycemic balance before, during and after the 2016 Paris Marathon using a real-time continuous glucose monitoring (RT-CGM) system in patients with type 1 diabetes mellitus in a prospective single-center observational study.

METHODS

Inclusion criteria were as follows: type 1 diabetes mellitus; age ≥18 years; HbA1c < 9%. Participants performed two 2h-preparatory races (PR) before the Marathon and were monitored with RT-CGM 24h before, during and 72h after each race. Hypoglycemic events were prevented via carbohydrate intake / insulin dose adjustments. The primary outcome was area under the curve (AUC) < 70 and > 200 mg/dl and percentage of time spent in euglycemia, hypoglycemia, and hyperglycemia during the races.

RESULTS

Twelve patients (2F/10M; median HbA1c=6.8%) were included and completed the study. Median AUC < 70 and time spent in hypoglycemia (< 70 mg/dl) during the PRs and Marathon were equal to 0. However, no hypoglycemic episodes occurred during Marathon, while two patients experienced hypoglycemia during PR1 and PR2. There was a significant increase in AUC > 200 mg/dl during races between PR2 and Marathon (P = 0.009) although the median time spent > 200mg/dl was not statistically different in Marathon versus PR2 (48.4% versus 18.4%; P = 0.09). Median time spent in euglycemia (70-200 mg/dl) was lower in Marathon versus PR2 (51.6 versus 58%; P = 0.03).

CONCLUSION

Our study proposes a medical support protocol for extreme endurance physical activity in patients with type 1 diabetes mellitus. Our results suggest that RT-CGM, coupled with adjustments in carbohydrate intake and insulin doses, appears to be effective to prevent hypoglycemia during and after exercise.

Prevalence of nocturnal hypoglycemia in free-living conditions in adults with type 1 diabetes: What is the impact of daily physical activity?

OBJECTIVE

Studies investigating strategies to limit the risk of nocturnal hypoglycemia associated with physical activity (PA) are scarce and have been conducted in standardized, controlled conditions in people with type 1 diabetes (T1D). This study sought to investigate the effect of daily PA level on nocturnal glucose management in free-living conditions while taking into consideration reported mitigation strategies to limit the risk of nocturnal hyoglycemia in people with T1D.

METHODS

Data from 25 adults (10 males, 15 females, HbA_1c: 7.6 ± 0.8%), 20-60 years old, living with T1D, were collected. One week of continuous glucose monitoring and PA (assessed using an accelerometer) were collected in free-living conditions. Nocturnal glucose values (midnight-6:00 am) following an active day "ACT" and a less active day "L-ACT" were analyzed to assess the time spent within the different glycemic target zones (<3.9 mmol/L; 3.9 - 10.0 mmol/L and >10.0 mmol/L) between conditions. Self-reported data about mitigation strategies applied to reduce the risk of nocturnal hypoglycemia was also analyzed.

RESULTS

Only 44% of participants reported applying a carbohydrate- or insulin-based strategy to limit the risk of nocturnal hypoglycemia on ACT day. Nocturnal hypoglycemia occurrences were comparable on ACT night versus on L-ACT night. Additional post-meal carbohydrate intake was higher on evenings following ACT (27.7 ± 15.6 g, ACT vs. 19.5 ± 11.0 g, L-ACT; P=0.045), but was frequently associated with an insulin bolus (70% of participants). Nocturnal hypoglycemia the night following ACT occurred mostly in people who administrated an additional insulin bolus before midnight (3 out of 5 participants with nocturnal hypoglycemia).

CONCLUSIONS

Although people with T1D seem to be aware of the increased risk of nocturnal hypoglycemia associated with PA, the risk associated with additional insulin boluses may not be as clear. Most participants did not report using compensation strategies to reduce the risk of PA related late-onset hypoglycemia which may be because they did not consider habitual PA as something requiring treatment adjustments.

Exercise, type 1 diabetes mellitus and blood glucose: The implications of exercise timing

The scientific literature shows that exercise has many benefits for individuals with type 1 diabetes. Yet, several barriers to exercise in this population exist, such as post-exercise hypoglycaemia or hyperglycaemia. Several studies suggest that the timing of exercise may be an important factor in preventing exercise-induced hypoglycaemia or hyperglycaemia. However, there is a paucity of evidence solely focused on summarising findings regarding exercise timing and the impact it has on glucose metabolism in type 1 diabetes. This report suggests that resistance or high-intensity interval exercise/training (often known as HIIT) may be best commenced at the time of day when an individual is most likely to experience a hypoglycaemic event (i.e., afternoon/evening) due to the superior blood glucose stability resistance and HIIT exercise provides. Continuous aerobic-based exercise is advised to be performed in the morning due to circadian elevations in blood glucose at this time, thereby providing added protection against a hypoglycaemic episode. Ultimately, the evidence concerning exercise timing and glycaemic control remains at an embryonic stage. Carefully designed investigations of this nexus are required, which could be harnessed to determine the most effective, and possibly safest, time to exercise for those with type 1 diabetes.

Nutritional support for a person with type 1 diabetes undertaking endurance swimming

Long distance and open water swimming have increased in popularity over recent years. Swimming a long distance in lakes, rivers and the sea present numerous challenges, including cold water exposure and maintaining adequate nutritional intake to fuel exercising muscles. Guidelines exist outlining issues to consider and potential solutions to overcome the difficulties in feeding athletes. Exercising with type 1 diabetes adds further complexity, mostly around matching insulin to the recommended high carbohydrate intake, but also because of the way in which higher circulating insulin levels affect glucose utilisation and fat oxidation. This paper describes the nutritional considerations for people with type 1 diabetes intending to undertake long distance open water events, and insulin management suggestions to trial alongside. In addition, we include personal testimony from a swimmer with type 1 diabetes describing the challenges and considerations he faced when undertaking marathon swimming.

Physical Activity, Dietary Patterns, and Glycemic Management in Active Individuals with Type 1 Diabetes: An Online Survey

Individuals with type 1 diabetes (T1D) are able to balance their blood glucose levels while engaging in a wide variety of physical activities and sports. However, insulin use forces them to contend with many daily training and performance challenges involved with fine-tuning medication dosing, physical activity levels, and dietary patterns to optimize their participation and performance. The aim of this study was to ascertain which variables related to the diabetes management of physically active individuals with T1D have the greatest impact on overall blood glucose levels (reported as A1C) in a real-world setting. A total of 220 individuals with T1D completed an online survey to self-report information about their glycemic management, physical activity patterns, carbohydrate and dietary intake, use of diabetes technologies, and other variables that impact diabetes management and health. In analyzing many variables affecting glycemic management, the primary significant finding was that A1C values in lower, recommended ranges (<7%) were significantly predicted by a very-low carbohydrate intake dietary pattern, whereas the use of continuous glucose monitoring (CGM) devices had the greatest predictive ability when A1C was above recommended (≥7%). Various aspects of physical activity participation (including type, weekly time, frequency, and intensity) were not significantly associated with A1C for participants in this survey. In conclusion, when individuals with T1D are already physically active, dietary changes and more frequent monitoring of glucose may be most capable of further enhancing glycemic management.

No more hypoglycaemia on days with physical activity and unrestricted diet when using a closed-loop system for 12 weeks: A post hoc secondary analysis of the multicentre, randomized controlled Diabeloop WP7 trial

A post hoc analysis of the Diabeloop WP7 multicentre, randomized controlled trial was performed to investigate the efficacy of the Diabeloop Generation-1 (DBLG1) closed-loop system in controlling the hypoglycaemia induced by physical activity (PA) in real-life conditions. Glycaemic outcomes were compared between days with and without PA in 56 patients with type 1 diabetes (T1D) using DBLG1 for 12 weeks. After the patient announces a PA, DBLG1 reduces insulin delivery and, if necessary, calculates the amount of preventive carbohydrates (CHO). Daily time spent in the interstitial glucose range less than 70 mg/dL was not significantly different between days with and without PA (2.0% ± 1.5% vs. 2.2% ± 1.1%), regardless of the intensity or duration of the PA. Preventive CHO intake recommended by the system was significantly higher in days with PA (41.1 ± 35.5 vs. 21.8 ± 28.5 g/day; P < .0001), and insulin delivery was significantly lower (31.5 ± 10.5 vs. 34.0 ± 10.5 U/day; P < .0001). The time spent in hyperglycaemia and the glycaemic variation coefficient increased significantly on days with PA. In real-life conditions, the use of DBLG1 avoids PA-induced hypoglycaemia. Insulin adjustments and preventive CHO recommendation may explain this therapeutic benefit.

American Association of Clinical Endocrinology Clinical Practice Guideline: The Use of Advanced Technology in the Management of Persons With Diabetes Mellitus

OBJECTIVE

To provide evidence-based recommendations regarding the use of advanced technology in the management of persons with diabetes mellitus to clinicians, diabetes-care teams, health care professionals, and other stakeholders.

METHODS

The American Association of Clinical Endocrinology (AACE) conducted literature searches for relevant articles published from 2012 to 2021. A task force of medical experts developed evidence-based guideline recommendations based on a review of clinical evidence, expertise, and informal consensus, according to established AACE protocol for guideline development.

MAIN OUTCOME MEASURES

Primary outcomes of interest included hemoglobin A1C, rates and severity of hypoglycemia, time in range, time above range, and time below range.

RESULTS

This guideline includes 37 evidence-based clinical practice recommendations for advanced diabetes technology and contains 357 citations that inform the evidence base.

RECOMMENDATIONS

Evidence-based recommendations were developed regarding the efficacy and safety of devices for the management of persons with diabetes mellitus, metrics used to aide with the assessment of advanced diabetes technology, and standards for the implementation of this technology.

CONCLUSIONS

Advanced diabetes technology can assist persons with diabetes to safely and effectively achieve glycemic targets, improve quality of life, add greater convenience, potentially reduce burden of care, and offer a personalized approach to self-management. Furthermore, diabetes technology can improve the efficiency and effectiveness of clinical decision-making. Successful integration of these technologies into care requires knowledge about the functionality of devices in this rapidly changing field. This information will allow health care professionals to provide necessary education and training to persons accessing these treatments and have the required expertise to interpret data and make appropriate treatment adjustments.

Effects of 12 weeks of recreational football (soccer) with caloric control on glycemia and cardiovascular health of adolescent boys with type 1 diabetes

OBJECTIVE

To determine the effects of recreational football combined with caloric control on glycemia and cardiovascular health of adolescent boys with type 1 diabetes.

BACKGROUND

Though 12 weeks of physical activity alone improves the health of people with type 1 diabetes, there is little evidence that physical activity alone can improve glycemia in 12 weeks.

RESEARCH DESIGN AND METHODS

The participants were divided into four groups as follows: football with diet, football-only, diet-only, and the control groups. Each group consisted of 10 participants. The football with diet and the football-only groups had 1.5 h of football twice a week for 12 weeks. The following outcomes were measured before and after 12 weeks: Glycated hemoglobin, fasting blood glucose, total cholesterol, high-density lipoprotein, low-density lipoprotein, triglycerides, and resting blood pressures. Changes were considered significant when p ≤ 0.050 and common language effect size ≤42% or common language effect size ≥58%.

RESULTS

Glycated hemoglobin decreased in the football with diet group (mean change (standard deviation) = -0.9 (1.0) %, p = 0.019, and common language effect size = 31.5%) and was different from the control group (p = 2.4 × 10^-4 and common language effect size = 95.5%.). However, none of the intervention groups showed a clear change in blood lipids nor blood pressure.

CONCLUSIONS

12 weeks of combined football with diet intervention provides the greatest improvement in glycemia in adolescent boys with type 1 diabetes.

Fear of hypoglycemia, a game changer during physical activity in type 1 diabetes mellitus patients

Hypoglycemia limits optimal glycemic management of patients with type 1 diabetes mellitus (T1DM). Fear of hypoglycemia (FoH) is a significant psychosocial consequence that negatively impacts the willingness of T1DM patients to engage in and profit from the health benefits of regular physical activity (e.g., cardiometabolic health, improved body composition, cardiovascular fitness, quality of life). Technological advances, improved insulin regimens, and a better understanding of the physiology of various types of exercise could help ameliorate FoH. This narrative review summarizes the available literature on FoH in children and adults and tools to avoid it.

Anticipation of Historical Exercise Patterns by a Novel Artificial Pancreas System Reduces Hypoglycemia During and After Moderate-Intensity Physical Activity in People with Type 1 Diabetes

Objective: Physical activity is a major challenge to glycemic control for people with type 1 diabetes. Moderate-intensity exercise often leads to steep decreases in blood glucose and hypoglycemia that closed-loop control systems have so far failed to protect against, despite improving glycemic control overall. Research Design and Methods: Fifteen adults with type 1 diabetes (42 ± 13.5 years old; hemoglobin A_1c 6.6% ± 1.0%; 10F/5M) participated in a randomized crossover clinical trial comparing two hybrid closed-loop (HCL) systems, a state-of-the-art hybrid model predictive controller and a modified system designed to anticipate and detect unannounced exercise (APEX), during two 32-h supervised admissions with 45 min of planned moderate activity, following 4 weeks of data collection. Primary outcome was the number of hypoglycemic episodes during exercise. Continuous glucose monitor (CGM)-based metrics and hypoglycemia are also reported across the entire admissions. Results: The APEX system reduced hypoglycemic episodes overall (9 vs. 33; P = 0.02), during exercise (5 vs. 13; P = 0.04), and in the 4 h following (2 vs. 11; P = 0.02). Overall CGM median percent time <70 mg/dL decreased as well (0.3% vs. 1.6%; P = 0.004). This protection was obtained with no significant increase in time >180 mg/dL (18.5% vs. 16.6%, P = 0.15). Overnight control was notable for both systems with no hypoglycemia, median percent in time 70-180 mg/dL at 100% and median percent time 70-140 mg/dL at ∼96% for both. Conclusions: A new closed-loop system capable of anticipating and detecting exercise was proven to be safe and feasible and outperformed a state-of-the-art HCL, reducing participants' exposure to hypoglycemia during and after moderate-intensity physical activity. ClinicalTrials.gov NCT03859401.

Carbohydrate Requirements for Prolonged, Fasted Exercise With and Without Basal Rate Reductions in Adults With Type 1 Diabetes on Continuous Subcutaneous Insulin Infusion

OBJECTIVE

Exercising while fasted with type 1 diabetes facilitates weight loss; however, the best strategy to maintain glucose stability remains unclear.

RESEARCH DESIGN AND METHODS

Fifteen adults on continuous subcutaneous insulin infusion completed three sessions of fasted walking (120 min at 45% VO_2max) in a randomized crossover design: 50% basal rate reduction, set 90 min pre-exercise (-90_min50%_BRR); usual basal rate with carbohydrate intake of 0.3 g/kg/h (CHO-only); and combined 50% basal rate reduction set at exercise onset with carbohydrate intake of 0.3 g/kg/h (Combo).

RESULTS

Combo had a smaller change in glucose (5 ± 47 mg/dL) versus CHO-only (-49 ± 61 mg/dL, P = 0.03) or -90_min50%_BRR (-34 ± 45 mg/dL). The -90_min50%_BRR strategy produced higher β-hydroxybutyrate levels (0.4 ± 0.3 vs. 0.1 ± 0.1 mmol/L) and greater fat oxidation (0.51 ± 0.2 vs. 0.39 ± 0.1 g/min) than CHO-only (both P < 0.05).

CONCLUSIONS

All strategies examined produced stable glycemia for fasted exercise, but a 50% basal rate reduction, set 90 min pre-exercise, eliminates carbohydrate needs and enhances fat oxidation better than carbohydrate feeding with or without a basal rate reduction set at exercise onset.

Minimizing the Risk of Exercise-Induced Glucose Fluctuations in People Living With Type 1 Diabetes Using Continuous Subcutaneous Insulin Infusion: An Overview of Strategies

Physical activity (PA) is important for individuals living with type 1 diabetes (T1D) due to its various health benefits. Nonetheless, maintaining adequate glycemic control around PA remains a challenge for many individuals living with T1D because of the difficulty in properly managing circulating insulin levels around PA. Although the most common problem is increased incidence of hypoglycemia during and after most types of PA, hyperglycemia can also occur. Accordingly, a large proportion of people living with T1D are sedentary partly due to the fear of PA-associated hypoglycemia. Continuous subcutaneous insulin infusion (CSII) offers a higher precision and flexibility to adjust insulin basal rates and boluses according to the individual's specific needs around PA practice. Indeed, for physically active patients with T1D, CSII can be a preferred option to facilitate glucose regulation. To our knowledge, there are no guidelines to manage exercise-induced hypoglycemia during PA, specifically for individuals living with T1D and using CSII. In this review, we highlight the current state of knowledge on exercise-related glucose variations, especially hypoglycemic risk and its underlying physiology. We also detail the current recommendations for insulin modulations according to the different PA modalities (type, intensity, duration, frequency) in individuals living with T1D using CSII.

Carbohydrate Requirement for Exercise in Type 1 Diabetes: Effects of Insulin Concentration

Physical activity is a keystone of a healthy lifestyle as well as of management of patients with type 1 diabetes. The risk of exercise-induced hypoglycemia, however, is a great challenge for these patients. The glycemic response to exercise depends upon several factors concerning the patient him/herself (eg, therapy, glycemic control, training level) and the characteristics of the exercise performed. Only in-depth knowledge of these factors will allow to develop individualized strategies minimizing the risk of hypoglycemia. The main factors affecting the exercise-induced hypoglycemia in patients with T1D have been analyzed, including the effects of insulin concentration. A model is discussed, which has the potential to become the basis for providing patients with individualized suggestions to keep constant glucose levels on each exercise occasion.

A single-blind, randomised, crossover study to reduce hypoglycaemia risk during postprandial exercise with closed-loop insulin delivery in adults with type 1 diabetes: announced (with or without bolus reduction) vs unannounced exercise strategies

AIMS/HYPOTHESIS

For individuals living with type 1 diabetes, closed-loop insulin delivery improves glycaemic control. Nonetheless, maintenance of glycaemic control during exercise while a prandial insulin bolus remains active is a challenge even to closed-loop systems. We investigated the effect of exercise announcement on the efficacy of a closed-loop system, to reduce hypoglycaemia during postprandial exercise.

METHODS

A single-blind randomised, crossover open-label trial was carried out to compare three strategies applied to a closed-loop system at mealtime in preparation for exercise taken 90 min after eating at a research testing centre: (1) announced exercise to the closed-loop system (increases target glucose levels) in addition to a 33% reduction in meal bolus (A-RB); (2) announced exercise to the closed-loop system and a full meal bolus (A-FB); (3) unannounced exercise and a full meal bolus (U-FB). Participants performed 60 min of exercise at 60% [Formula: see text] 90 min after eating breakfast. The investigators were not blinded to the interventions. However, the participants were blinded to the sensor glucose readings and to the insulin infusion rates throughout the intervention visits.

RESULTS

The trial was completed by 37 adults with type 1 diabetes, all using insulin pumps: mean±SD, 40.0 ± 15.0 years of age, HbA_1c 57.1 ± 10.8 mmol/mol (7.3 ± 1.0%). Reported results were based on plasma glucose values. During exercise and the following 1 h recovery period, time spent in hypoglycaemia (<3.9 mmol/l; primary outcome) was reduced with A-RB (mean ± SD; 2.0 ± 6.2%) and A-FB (7.0 ± 12.6%) vs U-FB (13.0 ± 19.0%; p < 0.0001 and p = 0.005, respectively). During exercise, A-RB had the least drop in plasma glucose levels: A-RB -0.3 ± 2.8 mmol/l, A-FB -2.6 ± 2.9 mmol/l vs U-FB -2.4 ± 2.7 mmol/l (p < 0.0001 and p = 0.5, respectively). Comparison of A-RB vs U-FB revealed a decrease in the time spent in target (3.9-10 mmol/l) by 12.7% (p = 0.05) and an increase in the time spent in hyperglycaemia (>10 mmol/l) by 21% (p = 0.001). No side effects were reported during the applied strategies.

CONCLUSIONS/INTERPRETATION

Combining postprandial exercise announcement, which increases closed-loop system glucose target levels, with a 33% meal bolus reduction significantly reduced time spent in hypoglycaemia compared with the other two strategies, yet at the expense of more time spent in hyperglycaemia.

TRIAL REGISTRATION

ClinicalTrials.gov NCT0285530 FUNDING: JDRF (2-SRA-2016-210-A-N), the Canadian Institutes of Health Research (354024) and the Fondation J.-A. DeSève chair held by RR-L.

Risk of hypoglycaemia associated with professional, recreational, and traffic-related activities in patients with type 2 diabetes: a cross-sectional study by questionnaire

AIMS

We aimed to quantify the exposure to physical exercise associated with professional, recreational, or traffic-related activities in patients with type 2 diabetes, which may provoke or aggravate hypoglycaemic episodes, and to assess whether such risks determine the choice of medications minimizing the risk of hypoglycaemia.

METHODS

In total, 203 patients with type 2 diabetes (98 women, 105 men, age 65 [56;72; median, inter-quartile range] years, diabetes duration 10 [5;15] years) were recruited from a German diabetes practice. A questionnaire assessed their engagement in professional, recreational, or traffic-related activities. The prescription insulin or sulphonylureas was quantified in relation to the number of such activities.

RESULTS

63.5% of the patients were treated with insulin, 7.4% with sulphonylureas, and 70.9% with either. Sixty-six patients (22.7%) were professionally active: 36 (54.4%) of those were professionally exposed to risky behaviour (14 [31.8%] patients with exposure to multiple risks and 20 (30.3%) who experienced hypoglycaemic episodes in the past year). In total, 194 (95.6%) patients were exposed to risky behaviour during recreational activities, 129 (63.6%) to multiple ones. All patients were exposed to traffic-related activities, 144 (70.9%) were exposed to more than being pedestrian, and 24 (11.8%) experienced hypoglycaemic episodes while in traffic.

CONCLUSIONS

Patients with type 2 diabetes are exposed to risks associated with professional, recreational, and traffic-related activities. We recommend a careful assessment of such risks before glucose-lowering medications with a potential for provoking hypoglycaemic episodes are prescribed.

Efficacy of Carbohydrate Supplementation Compared With Bolus Insulin Dose Reduction Around Exercise in Adults With Type 1 Diabetes: A Retrospective, Controlled Analysis

OBJECTIVES

Individuals with type 1 diabetes try to manage the risk of exercise-induced hypoglycemia by either pre-exercise/pre-meal bolus insulin dose reductions and/or consuming additional carbohydrates during exercise. Both strategies have proven to be effective in offsetting hypoglycemia, but it remains unclear which one is more beneficial. The aim of this study was to assess the efficacy of carbohydrate supplementation vs bolus insulin dose reduction in prevention of hypoglycemia during moderate-intensity exercise in those with type 1 diabetes.

METHODS

This investigation was a retrospective, controlled analysis of 2 independent clinical trials. All participants performed continuous, moderate-intensity cycle ergometer exercise for ∼45 minutes. Two therapy management groups and a control group were compared. Group A was supplemented with 15 to 30 g carbohydrates at a glycemic threshold of 7.0 mmol/L during exercise, group B reduced their individual bolus insulin dose by 50% with their last meal before exercise and group C served as a control.

RESULTS

No hypoglycemic events occurred in group A, whereas 4 events were recorded in groups B (p=0.02) and C (p=0.02).

CONCLUSIONS

Carbohydrate supplementation was superior to bolus insulin reduction for prevention of hypoglycemia during exercise in people with type 1 diabetes.

Flexible insulin therapy with a hybrid regimen of insulin degludec and continuous subcutaneous insulin infusion with pump suspension before exercise in physically active adults with type 1 diabetes (FIT Untethered): a single-centre, open-label, proof-of-concept, randomised crossover trial

BACKGROUND

People with type 1 diabetes who use continuous subcutaneous insulin infusion (CSII, or insulin pump therapy) often remove their pump before extended periods of exercise, but this approach might result in reduced glycaemic control and increased risk of hyperglycaemia and ketogenesis. We aimed to assess the efficacy and safety of a hybrid approach, in which basal insulin delivery was divided between CSII and a daily injection of insulin degludec.

METHODS

In this single-centre, open-label, proof-of-concept, randomised crossover trial done at the LMC Diabetes & Endocrinology research centre, we recruited physically active and aerobically fit participants aged 18 years or older with type 1 diabetes who were using CSII. Participants were randomly assigned (1:1) by use of a computer-generated sequence to one of two sequences of either usual CSII, involving the continuation of the participant's usual CSII regimen, followed by crossover to hybrid CSII, in which the delivery of the participant's usual daily basal insulin dose was split (50% delivered by CSII and 50% delivered by a once-daily morning injection of 100 U/mL insulin degludec), or the opposite sequence (ie, hybrid CSII followed by crossover to usual CSII). Treatment was not masked to the investigators or participants. For each intervention, participants completed a moderate-intensity and a high-intensity in-clinic exercise session in the first week, followed by four high-intensity and two moderate-intensity home-based exercise sessions in the subsequent 3 weeks. Insulin pumps were suspended or disconnected 60 min before exercise and reconnected immediately after exercise during both treatment regimens. The coprimary outcomes were: (1) time spent in the target control range of 4·0-10·0 mmol/L blood glucose after high-intensity exercise, and (2) time spent in target control range of 4·0-10·0 mmol/L blood glucose after moderate-intensity exercise, measured by continuous glucose monitoring in the 6-h period from the start of the high-intensity and moderate-intensity in-clinic exercise sessions. Outcomes were assessed in a modified intention-to-treat population that included all participants who started both intervention phases and completed all of the in-clinic exercise visits. This trial is registered with ClinicalTrials.gov, NCT03838783, and is complete.

FINDINGS

Between May 15, 2018, and March 5, 2019, we assessed 43 patients for eligibility, of whom 31 were randomly assigned to receive the usual CSII regimen (n=14) or hybrid CSII regimen (n=17) in the first phase (before crossover). The analysis population consisted of 24 participants who completed both study phases. Compared with the usual CSII regimen, participants on the hybrid CSII regimen had a significantly longer time in blood glucose range of 4-10 mmol/L during the 6-h period from the start of both moderate-intensity (mean difference 86 min [95% CI 61-147], p=0·005; percentage time in range 64% [SD 35] vs 40% [35]) and high-intensity in-clinic exercise session (60 min [11-109], p=0·01; 66% [32] vs 50% [27]). Participants on the hybrid CSII regimen also showed a higher time in blood glucose range of 4-10 mmol/L during home-based exercise sessions (mean difference 23 min [95% CI -1 to 46], p=0·055), with significantly lower time spent in hyperglycaemia than participants on the usual CSII regimen (mean difference 25 min [2-48], p=0·04). These exploratory outcomes also showed no significant difference in the amount of time spent in hypoglycaemia, nor the number of hypoglycaemic events, between the two interventions. There were three study-related adverse events reported with the usual CSII regimen (two hypotension events and one nausea event) and four with the hybrid CSII regimen (two hypotension events and two nausea events).

INTERPRETATION

A hybrid regimen of injected insulin degludec and CSII (with pump removal during exercise) appears to be safe and effective in adults with type 1 diabetes who exercise regularly. This approach could offer improved glycaemic control immediately after exercise and should be further assessed in a larger-scale randomised trial.

FUNDING

Novo Nordisk.

Efficacy of the Diabeloop closed-loop system to improve glycaemic control in patients with type 1 diabetes exposed to gastronomic dinners or to sustained physical exercise

AIMS

To compare closed-loop (CL) and open-loop (OL) systems for glycaemic control in patients with type 1 diabetes (T1D) exposed to real-life challenging situations (gastronomic dinners or sustained physical exercise).

METHODS

Thirty-eight adult patients with T1D were included in a three-armed randomized pilot trial (Diabeloop WP6.2 trial) comparing glucose control using a CL system with use of an OL device during two crossover 72-hour periods in one of the three following situations: large (gastronomic) dinners; sustained and repeated bouts of physical exercise (with uncontrolled food intake); or control (rest conditions). Outcomes included time in spent in the glucose ranges of 4.4-7.8 mmol/L and 3.9-10.0 mmol/L, and time in hypo- and hyperglycaemia.

RESULTS

Time spent overnight in the tight range of 4.4 to 7.8 mmol/L was longer with CL (mean values: 63.2% vs 40.9% with OL; P ≤ .0001). Time spent during the day in the range of 3.9 to 10.0 mmol/L was also longer with CL (79.4% vs 64.1% with OL; P ≤ .0001). Participants using the CL system spent less time during the day with hyperglycaemic excursions (glucose >10.0 mmol/L) compared to those using an OL system (17.9% vs 31.9%; P ≤ .0001), and the proportions of time spent during the day with hyperglycaemic excursions of those using the CL system in the gastronomic dinner and physical exercise subgroups were of similar magnitude to those in the control subgroup (18.1 ± 6.3%, 17.2 ± 8.1% and 18.4 ± 12.5%, respectively). Finally, times spent in hypoglycaemia were short and not significantly different among the groups.

CONCLUSIONS

The Diabeloop CL system is superior to OL devices in reducing hyperglycaemic excursions in patients with T1D exposed to gastronomic dinners, or exposed to physical exercise followed by uncontrolled food and carbohydrate intake.

Diabetes Technology and Exercise

Advances in technologies such as glucose monitors, exercise wearables, closed-loop systems, and various smartphone applications are helping many people with diabetes to be more physically active. These technologies are designed to overcome the challenges associated with exercise duration, mode, relative intensity, and absolute intensity, all of which affect glucose homeostasis in people living with diabetes. At present, optimal use of these technologies depends largely on motivation, competence, and adherence to daily diabetes care requirements. This article discusses recent technologies designed to help patients with diabetes to be more physically active, while also trying to improve glucose control around exercise.

The Athlete with Type 1 Diabetes: Transition from Case Reports to General Therapy Recommendations

Fear of hypoglycemia is a common barrier to exercise and physical activity for individuals with type 1 diabetes. While some of the earliest studies in this area involved only one or two participants, the link between exercise, exogenous insulin, and hypoglycemia was already clear, with the only suggested management strategies being to decrease insulin dosage and/or consume carbohydrates before and after exercise. Over the past 50 years, a great deal of knowledge has been developed around the impact of different types and intensities of exercise on blood glucose levels in this population. Recent decades have also seen the development of technologies such as continuous glucose monitors, faster-acting insulins and commercially available insulin pumps to allow for the real-time observation of interstitial glucose levels, and more precise adjustments to insulin dosage before, during and after activity. As such, there are now evidence-based exercise and physical activity guidelines for individuals with type 1 diabetes. While the risk of hypoglycemia has not been completely eliminated, therapy recommendations have evolved considerably. This review discusses the evolution of the knowledge and the technology related to type 1 diabetes and exercise that have allowed this evolution to take place.

Carbohydrate Intake in the Context of Exercise in People with Type 1 Diabetes

Although the benefits of regular exercise on cardiovascular risk factors are well established for people with type 1 diabetes (T1D), glycemic control remains a challenge during exercise. Carbohydrate consumption to fuel the exercise bout and/or for hypoglycemia prevention is an important cornerstone to maintain performance and avoid hypoglycemia. The main strategies pertinent to carbohydrate supplementation in the context of exercise cover three aspects: the amount of carbohydrates ingested (i.e., quantity in relation to demands to fuel exercise and avoid hypoglycemia), the timing of the intake (before, during and after the exercise, as well as circadian factors), and the quality of the carbohydrates (encompassing differing carbohydrate types, as well as the context within a meal and the associated macronutrients). The aim of this review is to comprehensively summarize the literature on carbohydrate intake in the context of exercise in people with T1D.

Artificial Pancreas Systems and Physical Activity in Patients with Type 1 Diabetes: Challenges, Adopted Approaches, and Future Perspectives

Physical activity is important for patients living with type 1 diabetes (T1D) but limited by the challenges associated with physical activity induced glucose variability. Optimizing glycemic control without increasing the risk of hypoglycemia is still a hurdle despite many advances in insulin formulations, delivery methods, and continuous glucose monitoring systems. In this respect, the artificial pancreas (AP) system is a promising therapeutic option for a safer practice of physical activity in the context of T1D. It is important that healthcare professionals as well as patients acquire the necessary knowledge about how the AP system works, its limits, and how glucose control is regulated during physical activity. This review aims to examine the current state of knowledge on exercise-related glucose variations especially hypoglycemic risk in T1D and to discuss their effects on the use and development of AP systems. Though effective and highly promising, these systems warrant further research for an optimized use around exercise.

The hypoglycemia associated autonomic failure triggered by exercise in the patients with "brittle" diabetes and the strategy for prevention

Exercise is a fundamental component of diabetes management. However, choosing inappropriate type or timing of exercise is associated with mild or severe hypoglycemia either during exercise or several hours after exercise. Several studies have shown that impaired counterregulatory responses triggers hypoglycemia. Therefore, in this investigation, we explored the appropriate intensity and time of exercise in patients with diabetes. The mechanisms of counterregulatory responses and hypoglycemia associated autonomic failure (HAAF), as well as the strategies for preventing episodes of hypoglycemia after exercise were also investigated. In this study, we obtained the following results: 1) High intensity interval exercise is more suitable for diabetic patients. 2) Morning exercise reduces nocturnal hypoglycemia risks compared with midday, afternoon and evening exercise. 3) Hypoglycemia can be prevented by dietary approach, reduction or suspension of insulin dose, use of mini dose glucagon, caffeine, mitigation methods, prediction algorithm, autonomic feedback controlled close-loop insulin delivery, real time continuous glucose monitoring. Based on these results we concluded that exercise may cause severe hypoglycemia or induce blunted response in patients with diabetes. For Diabetes Mellitus (DM) patients, the intensity and time of exercise influence the occurrence of hypoglycemia. This review summarizes the clinical characteristics of different types of exercises and time of exercise that can be potentially used to educate and guide patients regarding the role of exercise in standard of care.

Prediction of Hypoglycemia During Aerobic Exercise in Adults With Type 1 Diabetes

BACKGROUND

Fear of exercise related hypoglycemia is a major reason why people with type 1 diabetes (T1D) do not exercise. There is no validated prediction algorithm that can predict hypoglycemia at the start of aerobic exercise.

METHODS

We have developed and evaluated two separate algorithms to predict hypoglycemia at the start of exercise. Model 1 is a decision tree and model 2 is a random forest model. Both models were trained using a meta-data set based on 154 observations of in-clinic aerobic exercise in 43 adults with T1D from 3 different studies that included participants using sensor augmented pump therapy, automated insulin delivery therapy, and automated insulin and glucagon therapy. Both models were validated using an entirely new validation data set with 90 exercise observations collected from 12 new adults with T1D.

RESULTS

Model 1 identified two critical features predictive of hypoglycemia during exercise: heart rate and glucose at the start of exercise. If heart rate was greater than 121 bpm during the first 5 min of exercise and glucose at the start of exercise was less than 182 mg/dL, it predicted hypoglycemia with 79.55% accuracy. Model 2 achieved a higher accuracy of 86.7% using additional features and higher complexity.

CONCLUSIONS

Models presented here can assist people with T1D to avoid exercise related hypoglycemia. The simple model 1 heuristic can be easily remembered (the 180/120 rule) and model 2 is more complex requiring computational resources, making it suitable for automated artificial pancreas or decision support systems.

An on-line support tool to reduce exercise-related hypoglycaemia and improve confidence to exercise in type 1 diabetes

OBJECTIVE

Hypoglycaemia related to exercise and lack of confidence to exercise, are common in T1DM. An online educational exercise tool (ExT1D) was tested to determine whether these parameters can be improved.

RESEARCH DESIGN AND METHODS

Thirty two adults with T1DM (50%M, age 35.8 ± 9.5 yr diabetes duration 12.3 ± 9.9 yr, median HbA1c 7.1%[ICR 6.4-7.7] NGSPU) exercising ≥ 60 min/week enrolled in a RCT utilising ExT1D, with partial cross-over design. The primary end-point was Exercise-related hypoglycaemia (ErH) number corrected for exercise session number, with ErH defined as CGM episodes < 4.0 mM occurring within 24 h of exercise. Secondary RCT endpoints were total ErH duration, and ErH duration/episode. A pre-defined longitudinal analysis with each subject compared with their baseline was also undertaken, for the three ErH parameters, and using fear of hypoglycaemia questionnaires.

RESEARCH

In the RCT a 50% lower median ErH number (P = 0.6) (37% lower ErH number per exercise session (P = 0.06, NS primary endpoint) occurred in the Intervention vs Control group. A 49% lower ErH duration per episode (P = 0.2), and 80% less ErH duration (P = 0.3), were also observed in the Intervention vs Control group. In the longitudinal study, ErH number reduced by 43% (P = 0.088), ErH duration per episode by 52% (P = 0.157) and total duration of ErH fell by 71% (P = 0.015). Confidence to prevent glucose lowering by exercise also improved (P = 0.039). Post-hoc analysis showed those with the greatest ErH events at baseline benefited most. Fructosamine and HbA1c levels were unchanged from baseline.

CONCLUSIONS

ExT1D can reduce exercise-related hypoglycaemia and provide greater confidence to exercise.

Timing of insulin basal rate reduction to reduce hypoglycemia during late post-prandial exercise in adults with type 1 diabetes using insulin pump therapy: A randomized crossover trial

AIMS

To compare the efficacy of three timings to decrease basal insulin infusion rate to reduce exercise-induced hypoglycaemia in patients with type 1 diabetes (T1D) using pump therapy.

METHODS

A single-blinded, randomized, 3-way crossover study in 22 adults that had T1D > 1 year and using insulin pump > 3 months (age, 40 ± 15 years; HbA_1c, 56.3 ± 10.2 mmol/mol). Participants practiced three 45-min exercise sessions (ergocyle) at 60% VO_2peak 3 hours after lunch comparing an 80% reduction of basal insulin applied 40 minutes before (T-40), 20 minutes before (T-20) or at exercise onset (T0).

RESULTS

No significant difference was observed for percentage of time spent < 4.0 mmol/L (T-40: 16 ± 25%; T-20: 26 ± 27%; T0: 24 ± 29%) (main outcome) and time spent in target range 4.0-10.0 mmol/L (T-40: 63 ± 37%; T-20: 66 ± 25%; T0: 65 ± 31%). With T-40 strategy, although not significant, starting blood glucose (BG) was higher (T-40: 8.6 ± 3.6 mmol/L; T-20: 7.4 ± 2.5 mmol/L ; T0: 7.4 ± 2.7 mmol/L), fewer patients needed extra carbohydrates consumption prior to exercise for BG < 5.0 mmol/L (T-40: n = 3; T-20: n = 5; T0: n = 6) as well as during exercise for BG < 3.3 mmol/L [T-40: n = 6 (27%); T-20: n = 12 (55%); T0: n = 11 (50%)] while time to first hypoglycaemic episode was delayed (T-40: 28 ± 14 min; T-20: 24 ± 10 min; T0: 22 ± 11 min).

CONCLUSION

Decreasing basal insulin infusion rate by 80% up to 40 minutes before exercise onset is insufficient to reduce exercise-induced hypoglycaemia.

Improved Open-Loop Glucose Control With Basal Insulin Reduction 90 Minutes Before Aerobic Exercise in Patients With Type 1 Diabetes on Continuous Subcutaneous Insulin Infusion

OBJECTIVE

To reduce exercise-associated hypoglycemia, individuals with type 1 diabetes on continuous subcutaneous insulin infusion typically perform basal rate reductions (BRRs) and/or carbohydrate feeding, although the timing and amount of BRRs necessary to prevent hypoglycemia are unclear. The goal of this study was to determine if BRRs set 90 min pre-exercise better attenuate hypoglycemia versus pump suspension (PS) at exercise onset.

RESEARCH DESIGN AND METHODS

Seventeen individuals completed three 60-min treadmill exercise (∼50% of VO_2peak) visits in a randomized crossover design. The insulin strategies included 1) PS at exercise onset, 2) 80% BRR set 90 min pre-exercise, and 3) 50% BRR set 90 min pre-exercise.

RESULTS

Blood glucose level at exercise onset was higher with 50% BRR (191 ± 49 mg/dL) vs. 80% BRR (164 ± 41 mg/dL; P < 0.001) and PS (164 ± 45 mg/dL; P < 0.001). By exercise end, 80% BRR showed the smallest drop (-31 ± 58 mg/dL) vs. 50% BRR (-47 ± 50 mg/dL; P = 0.04) and PS (-67 ± 41 mg/dL; P < 0.001). With PS, 7 out of 17 participants developed hypoglycemia versus 1 out of 17 in both BRR conditions (P < 0.05). Following a standardized meal postexercise, glucose rose with PS and 50% BRR (both P < 0.05), but failed to rise with 80% BRR (P = 0.16). Based on interstitial glucose, overnight mean percent time in range was 83%, 83%, and 78%, and time in hypoglycemia was 2%, 1%, and 5% with 80% BRR, 50% BRR, and PS, respectively (all P > 0.05).

CONCLUSIONS

Overall, a 50-80% BRR set 90 min pre-exercise improves glucose control and decreases hypoglycemia risk during exercise better than PS at exercise onset, while not compromising the postexercise meal glucose control.

Impact of physical exercise on sensor performance of the FreeStyle Libre intermittently viewed continuous glucose monitoring system in people with Type 1 diabetes: a randomized crossover trial

AIMS

To evaluate the sensor performance of the FreeStyle Libre intermittently viewed continuous glucose monitoring system using reference blood glucose levels during moderate-intensity exercise while on either full or reduced basal insulin dose in people with Type 1 diabetes.

METHODS

Ten participants with Type 1 diabetes [four women, mean ± sd age 31.4 ± 9.0 years, BMI 25.5±3.8 kg/m² , HbA_1c 55±7 mmol/mol (7.2±0.6%)] exercised on a cycle ergometer for 55 min at a moderate intensity for 5 consecutive days at the clinical research facility, while receiving either their usual or a 75% basal insulin dose. After a 4-week washout period, participants performed the second exercise period having switched to the alternative basal insulin dose. During exercise, reference capillary blood glucose values were analysed using the fully enzymatic-amperometric method and compared with the interstitial glucose values obtained. Intermittently viewed continuous glucose monitoring accuracy was analysed according to median (interquartile range) absolute relative difference, and Clarke error grid and Bland-Altman analysis for overall glucose levels during exercise, stratified by glycaemic range and basal insulin dosing scheme (P<0.05).

RESULTS

A total of 845 glucose values were available during exercise to evaluate intermittently viewed continuous glucose monitoring sensor performance. The median (interquartile range) absolute relative difference between the reference values and those obtained by the sensor across the glycaemic range overall was 22 (13.9-29.7)%, and was 36.3 (24.2-45.2)% during hypoglycaemia, 22.8 (14.6-30.6)% during euglycaemia and 15.4 (9-21)% during hyperglycaemia. Usual basal insulin dose was associated with a worse sensor performance during exercise compared with the reduced (75%) basal insulin dose [median (interquartile range) absolute relative difference: 23.7 (17.2-30.7)% vs 20.5 (12-28.1)%; P<0.001).

CONCLUSIONS

The intermittently viewed continuous glucose monitoring sensor showed diminished accuracy during exercise. Absolute glucose readings derived from the sensor should be used cautiously and need confirmation by additional finger-prick blood glucose measurements.

Use of continuous glucose monitoring for sport in type 1 diabetes

Background

The benefits of exercise for patients with type 1 diabetes (T1D) are difficult to balance with associated glycaemic excursions. The aim of this cohort study was to show that continuous glucose monitoring (CGM) could reduce glycaemic excursions in patients with T1D already using insulin pumps, exercising at moderate to high intensity.

Methods

Questionnaires were used to identify patients with T1D using insulin pumps and naive to CGM use, who reported regular exercise. Six were enrolled and trained on Enlite sensor use with Medtronic Minimed Paradigm Veo system and given activity trackers and written advice on adjustment of insulin or carbohydrate intake for exercise. Resting heart rate (HR) and age were used to determine HR surrogates of moderate and high-intensity exercise. They were to exercise as usual for 3 weeks (run-in week, week 1 and week 2) using the activity trackers and heart rate monitors. Problem areas in Diabetes, Hypoglycaemia fear survey II, Diabetes Technology Questionnaire and Gold scores were completed prior to run-in and at the end. The downloaded sensor glucose data were used to compare the change in time in range (glucose 3.9–10.0 mmol/L) from week 1 to week 2.

Results

For the duration of exercise, this time in glucose range increased from 72±20 to 88%±16 %, p=0.05. The time in hypoglycaemia range (glucose < 3.9 mmol/L) went from 3.9±7.9 to 2.4%±4.8 %, p=0.39. The time in hyperglycaemia range (> 10 mmol/L) reduced from 24±19 to 10%±17%, p=0.04.

Conclusion

These results demonstrate the benefit of CGM use for patients with T1DM doing moderate-intensity to high-intensity exercise.

Exercise Management for Young People With Type 1 Diabetes: A Structured Approach to the Exercise Consultation

Regular physical activity during childhood is important for optimal physical and psychological development. For individuals with Type 1 Diabetes (T1D), physical activity offers many health benefits including improved glycemic control, cardiovascular function, blood lipid profiles, and psychological well-being. Despite these benefits, many young people with T1D do not meet physical activity recommendations. Barriers to engaging in a physically active lifestyle include fear of hypoglycemia, as well as insufficient knowledge in managing diabetes around exercise in both individuals and health care professionals. Diabetes and exercise management is complex, and many factors can influence an individual's glycemic response to exercise including exercise related factors (such as type, intensity and duration of the activity) and person specific factors (amount of insulin on board, person's stress/anxiety and fitness levels). International guidelines provide recommendations for clinical practice, however a gap remains in how to apply these guidelines to a pediatric exercise consultation. Consequently, it can be challenging for health care practitioners to advise young people with T1D how to approach exercise management in a busy clinic setting. This review provides a structured approach to the child/adolescent exercise consultation, based on a framework of questions, to assist the health care professional in formulating person-specific exercise management plans for young people with T1D.

Avoiding hypoglycemia: the use of insulin pump combined with continuous glucose monitor in type 1 diabetes crossing a Rocky Gorge

BACKGROUND

Continuous subcutaneous insulin infusion (CSII) and continuous glucose monitoring systems (CGMS) have been proven very effective in diabetes management.

AIM

This study evaluated the usefulness of these devices during prolonged, intense physical activity in an uncontrolled natural environment away from the clinical research center.

DESIGN

Non-randomized, prospective and observational study.

METHODS

During the summer, 38 participants with type 1 diabetes crossed the Samaria gorge, the second largest gorge in Europe (17 km). Twenty subjects on CSII combined with real-time CGMS and 18 on multiple daily injections (MDI) combined with professional (retrospective) CGMS participated in the program. All participants were unsupervised during the event.

RESULTS

All 38 participants managed to reach the destination point safely. There were no episodes of severe hypoglycemia. The duration of the exercise (mean ±SD) was 6.4 ± 1.3 h. The CSII group exhibited significantly lower hypoglycemic episodes during exercise (0.1 ± 0.3 vs. 0.4 ± 0.6; P = 0.047) as well as lower AUC below 70 mg/dl compared with the MDI, during the 24 h (0.61 ± 0.78 vs. 1.84 ± 1.55; P = 0.007). Individuals on CSII were significantly less likely to develop a hypoglycemic episode during exercise (P = 0.038). Exercise induced nocturnal hypoglycemia was not prevented effectively in neither group.

CONCLUSIONS

CSII combined with CGMS is effective in controlling blood glucose levels in type 1 diabetics who perform prolonged strenuous exercise. The use of insulin pump technology in regions with hot Mediterranean climates is safe and can provide protection against exercise-induced hypoglycemia. Development of precise instructions for T1DM who occasionally get involved in exercise activities, requires further studies.

Mini-Dose Glucagon as a Novel Approach to Prevent Exercise-Induced Hypoglycemia in Type 1 Diabetes

OBJECTIVE

Patients with type 1 diabetes who do aerobic exercise often experience a drop in blood glucose concentration that can result in hypoglycemia. Current approaches to prevent exercise-induced hypoglycemia include reduction in insulin dose or ingestion of carbohydrates, but these strategies may still result in hypoglycemia or hyperglycemia. We sought to determine whether mini-dose glucagon (MDG) given subcutaneously before exercise could prevent subsequent glucose lowering and to compare the glycemic response to current approaches for mitigating exercise-associated hypoglycemia.

RESEARCH DESIGN AND METHODS

We conducted a four-session, randomized crossover trial involving 15 adults with type 1 diabetes treated with continuous subcutaneous insulin infusion who exercised fasting in the morning at ∼55% VO_2max for 45 min under conditions of no intervention (control), 50% basal insulin reduction, 40-g oral glucose tablets, or 150-μg subcutaneous glucagon (MDG).

RESULTS

During exercise and early recovery from exercise, plasma glucose increased slightly with MDG compared with a decrease with control and insulin reduction and a greater increase with glucose tablets (P < 0.001). Insulin levels were not different among sessions, whereas glucagon increased with MDG administration (P < 0.001). Hypoglycemia (plasma glucose <70 mg/dL) was experienced by six subjects during control, five subjects during insulin reduction, and none with glucose tablets or MDG; five subjects experienced hyperglycemia (plasma glucose ≥250 mg/dL) with glucose tablets and one with MDG.

CONCLUSIONS

MDG may be more effective than insulin reduction for preventing exercise-induced hypoglycemia and may result in less postintervention hyperglycemia than ingestion of carbohydrate.

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.

Continuous Glucose Monitoring and Exercise in Type 1 Diabetes: Past, Present and Future

Prior to the widespread use of continuous glucose monitoring (CGM), knowledge of the effects of exercise in type 1 diabetes (T1D) was limited to the exercise period, with few studies having the budget or capacity to monitor participants overnight. Recently, CGM has become a staple of many exercise studies, allowing researchers to observe the otherwise elusive late post-exercise period. We performed a strategic search using PubMed and Academic Search Complete. Studies were included if they involved adults with T1D performing exercise or physical activity, had a sample size greater than 5, and involved the use of CGM. Upon completion of the search protocol, 26 articles were reviewed for inclusion. While outcomes have been variable, CGM use in exercise studies has allowed the assessment of post-exercise (especially nocturnal) trends for different exercise modalities in individuals with T1D. Sensor accuracy is currently considered adequate for exercise, which has been crucial to developing closed-loop and artificial pancreas systems. Until these systems are perfected, CGM continues to provide information about late post-exercise responses, to assist T1D patients in managing their glucose, and to be useful as a tool for teaching individuals with T1D about exercise.

Pre-exercise blood glucose affects glycemic variation of aerobic exercise in patients with type 2 diabetes treated with continuous subcutaneous insulin infusion

AIMS

Considering the insulin sensitivity may increase by exercise particularly in patients with type 2 diabetes (T2D), glycemic variation during exercise needs to be studied when the patients are treated with insulin. This study aimed to explore the influence factors of the efficacy and safety of aerobic exercise in patients with T2D treated with Continuous Subcutaneous Insulin Infusion (CSII).

METHODS

A total of 267 patients with T2D, treated with CSII, were included. Glycemic variations were assessed by continuous glucose monitoring (CGM). Patients were asked to complete 30 min aerobic exercise for at least one time during CGM. The patients were divided into effective and ineffective group by incremental glucose area under curve from 0 to 60 min after exercise (AUC_{0-60 min}).

RESULTS

The patients completed a total of 776 times of aerobic exercises. Blood glucose decreased fastest in the first 60 min of exercise. Pre-exercise blood glucose (PEBG) was negatively correlated with AUC_{0-60 min} (standardized β = -0.386, P < 0.001) and incremental AUC of blood glucose ≤ 4.4 mmol/L (standardized β = -0.078, P = 0.034), and was significantly higher in effective group than in ineffective group (P < 0.001). The Δglucose AUC_{0-60 min} during post-dinner was significantly higher than that during pre-lunch, post-lunch and pre-dinner (P < 0.05 for all).

CONCLUSIONS

PEBG is positively correlated with efficacy of aerobic exercise. Aerobic exercise will not worsen hyperglycemia when the PEBG > 16.7 mmol/L. Post-dinner exercise decreases the blood glucose better than other periods of the day.

CLINICAL TRIALS REGISTRATION

ChiCTR-ONC-17010400, www.chictr.org.cn.

Optimization of Insulin Regimen and Glucose Outcomes with Short-Term Real-Time Continuous Glucose Monitoring in Adult Type 1 Diabetes Patients with Suboptimal Control on Multiple Daily Injections: The Adult DIACCOR Study

BACKGROUND

The impact of a 7-day real-time continuous glucose monitoring (RT-CGM) on type 1 diabetes (T1D) management remains unclear in patients suboptimally controlled by multiple daily injections (MDI). The DIACCOR Study aimed to describe treatment decisions and glucose outcomes after a short-term RT-CGM sequence.

PATIENTS AND METHODS

This French multicenter longitudinal observational study included T1D patients with HbA1c >7.5% or history of severe hypoglycemia (SH) or recurrent documented hypoglycemia. A sensor was inserted at the inclusion visit, treatment changes were proposed by the investigator within 7-15 days ("INT" = MDI intensification, "CSII" = switch to continuous insulin infusion, or "ER" = educational reinforcement with no change in insulin regimen), and a 4-month follow-up visit (M4) was scheduled.

RESULTS

Four hundred fifty-nine patients were recruited by 155 diabetologists, 17.0% had SH history, and 24.2% had recurrent hypoglycemia. Baseline HbA1c was 8.34% ± 1.21% (>7.5% in 79.6%). Overall, 253 (64.4%), 64 (16.3%), and 76 patients (19.3%) were, respectively, included in the "INT," "CSII," and "ER" subgroups. The number of patients who experienced SH or recurrent hypoglycemia dropped dramatically (7.9% vs. 17.0% and 10.8% vs. 24.2%, respectively). The same trend was observed for ketoacidosis and ketosis (0.3% vs. 3.3% and 2.2% vs. 4.8%). At M4, HbA1c was significantly reduced in the whole cohort to 7.98% ± 1.01% (P < 0.0001). The adjusted differences in HbA1c level in the INT, CSII, and ER subgroups were, respectively, -0.32%, -0.69%, and -0.50% (P < 0.0001 for all).

CONCLUSION

In real-life setting, a 1-week diagnostic RT-CGM supports appropriate treatment changes in patients with uncontrolled T1D resulting in better glucose control and less hypoglycemia.

The Benefits and Limits of Technological Advances in Glucose Management Around Physical Activity in Patients Type 1 Diabetes

Physical activity is highly recommended for patients living with type 1 diabetes (T1D) due to its varied health benefits. Nevertheless, glucose management, during and in the hours following exercise, represents a great challenge for these patients who most often end up leading a sedentary life style. Important technological advances in insulin delivery devices and glucose monitoring are now available and continue to progress. These technologies could be used to alleviate glucose management related to physical activity in T1D. Continuous glucose monitoring (CGM) helps patients observe the trends of glycemic fluctuations when exercising and in the following night to deal pre-emptively with hypoglycemic risks and treat hypoglycemic episodes in a timely manner. Insulin pumps offer the flexibility of adjusting insulin basal rates and boluses according to patient's specific needs around exercise. The artificial pancreas links CGM to pump through an intelligent hormone dosing algorithm to close the loop of glucose control and has thus the potential to ease the burden of exercise in T1D. This review will examine and discuss the literature related to physical activity practice using each of these technologies. The aim is to discuss their benefits as well as their limitations and finally the additional research needed in the future to optimize their use in T1D.

10th Annual Symposium on Self-Monitoring of Blood Glucose, April 27-29, 2017, Warsaw, Poland

International experts in the field of diabetes and diabetes technology met in Warsaw, Poland, for the 10th Annual Symposium on Self-Monitoring of Blood Glucose. The goal of these meetings is to establish a global network of experts to facilitate new collaborations and research projects that can improve the lives of people with diabetes. The 2017 meeting comprised a comprehensive scientific program, parallel interactive workshops, and four keynote lectures.