A new table for prevention of hypoglycaemia during physical activity in type 1 diabetic patients

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).

Recovery Phase Nutrition and Insulin Strategies for a Collegiate Distance Runner with Type 1 Diabetes Mellitus: A Case Study

PURPOSE

There is scant published research regarding nutrition and insulin strategies for athletic performance in collegiate distance runners with type 1 diabetes mellitus (CDRT1). Acute carbohydrate supplementation (CHOsup) and insulin reduction used to minimize hypoglycemia during exercise may result in deteriorated glycemic control post exercise in CDRT1. The present case study of a CDRT1 investigated outcomes associated with a moderate-carbohydrate (ModCHO) diet and 24 h insulin adjustment during recovery phases for improved glycemic control and reduced use of acute strategies.

METHODS

During an 8-day period, a female CDRT1 followed a ModCHO (~4 g/kg/day) nutrition program. Recovery phase adjustments to insulin doses were made using an equation developed to estimate reduced insulin needs post exercise, as a function of exercise intensity and duration. Daily training was performed in the fasted state at 6:00 a.m. and included additional exercise strategies to reduce glycemic variability when needed. Daily blood glucose time-in-range (TIR) and use of CHOsup were assessed. Athlete well-being was determined using the Student-Athlete Well-Being Scale (SAWS)TM at baseline, and days 1, 3, and 7.

RESULTS

Throughout the 8-day period, mean TIR increased (77% versus < 50%) and the magnitude of glycemic excursions decreased (~3.8-15 versus ~3.0-26 mmol/L) relative to a prior comparison period. Minimal pre-exercise CHOsup was employed and CHOsup during exercise was not required. Additionally, the athlete achieved a new lifetime best in the 5000 m run and maintained positive well-being.

CONCLUSION

The present case study provides examples of recovery phase strategies (i.e., ModCHO diet and 24 h insulin adjustments) that may support glycemic control and athletic performance in CDRT1 and provides potential considerations for nutrition and insulin strategies for use by athletes and coaches.

The complex relationship between physical activity and diabetes: an overview

Diabetes mellitus (DM) is a widespread condition, representing a challenging disease to manage. Exercise is being increasingly recommended as part of the therapeutic regimen for DM but the management of different forms of physical activity is difficult for individuals with diabetes, trainers, and physicians. Regular exercise can improve health and well-being, helping individuals to achieve their target lipid profile, body composition, cardio-respiratory fitness, and glycemic goals. People with diabetes tend to be as inactive as the general population, with a large percentage of individuals not achieving the minimum amount of recommended physical activity levels. Indeed, several barriers to exercise exist for persons with diabetes, including sports eligibility, multi-modality management of diabetic athletes, and inadequate knowledge about adequate type and intensity of exercise. The aim of the present review is to provide the current understanding of mechanisms, recommendations, and beneficial effects of different modalities of exercise for the treatment of DM.

Comparing Two Treatment Approaches for Patients with Type 1 Diabetes During Aerobic Exercise: a Randomised, Crossover Study

BACKGROUND

In a randomised, counterbalanced, crossover design, eight men with type 1 diabetes (T1D; mean ± SD age, 27.6 ± 11.4 years) reduced insulin (INS) by 50% of their normal dose or consumed carbohydrates equivalent to 1 g of carbohydrate per kilogramme of their body weight without the usual insulin bolus (CARBS) over two sessions, held a week apart. Each session included standardised meals, a 45-min treadmill walk at 7.24 km h-1 and a 6-min walk test (6MWT). Rate of perceived exertion (RPE), blood glucose, ketone and lactate measures were taken before, during and immediately after the aerobic exercise. The distance covered in metres and the predicted VO2 max (mL kg-1 min-1) were also calculated for the 6MWT.

RESULTS

Participants completing the INS intervention spent more time in normoglycaemia (242 ± 135 min vs 88 ± 132 min; P < 0.01) and less time in hyperglycaemia (41 ± 95 min vs 154 ± 125 min; P = 0.01) as compared to the CARBS intervention. Mild hypoglycaemia occurred in two participants during INS and no participants during CARBS. Furthermore, there was no significant difference for blood lactate, ketone, RPE, distance covered and predicted VO2 max between interventions.

CONCLUSION

Based on this pilot study, INS intervention appears to be the best approach for maintaining blood glucose levels in those with T1D during aerobic exercise, though this does need evaluation in other groups, including women, children and those with suboptimal glycaemic control.

TRIAL REGISTRATION

Australian New Zealand Clinical Trial Registry, ACTRN12619001397101p . Registered 09 September 2019.

Automatically accounting for physical activity in insulin dosing for type 1 diabetes

BACKGROUND AND OBJECTIVE

Type 1 diabetes is a disease characterized by lifelong insulin administration to compensate for the autoimmune destruction of insulin-producing pancreatic beta-cells. Optimal insulin dosing presents a challenge for individuals with type 1 diabetes, as the amount of insulin needed for optimal blood glucose control depends on each subject's varying needs. In this context, physical activity represents one of the main factors altering insulin requirements and complicating treatment decisions. This work aims to develop and test in simulation a data-driven method to automatically incorporate physical activity into daily treatment decisions to optimize mealtime glycemic control in individuals with type 1 diabetes.

METHODS

We leveraged glucose, insulin, meal and physical activity data collected from twenty-three individuals to develop a method that (i) tracks and quantifies the accumulated glycemic impact from daily physical activity in real-time, (ii) extracts an individualized routine physical activity profile, and (iii) adjusts insulin doses according to the prolonged changes in insulin needs due to deviations in daily physical activity in a personalized manner. We used the data replay simulation framework developed at the University of Virginia to "re-simulate" the clinical data and estimate the performances of the new decision support system for physical activity informed insulin dosing against standard insulin dosing. The paired t-test is used to compare the performances of dosing methods with p < 0.05 as the significance threshold.

RESULTS

Simulation results show that, compared with standard dosing, the proposed physical-activity informed insulin dosing could result in significantly less time spent in hypoglycemia (15.3± 8% vs. 11.1± 4%, p = 0.007) and higher time spent in the target glycemic range (66.1± 11.7% vs. 69.6± 12.2%, p < 0.01) and no significant difference in the time spent above the target range(26.6± 1.4 vs. 27.4± 0.1, p = 0.5).

CONCLUSIONS

Integrating daily physical activity, as measured by the step count, into insulin dose calculations has the potential to improve blood glucose control in daily life with type 1 diabetes.

A Single Load of Fructose Attenuates the Risk of Exercise-Induced Hypoglycemia in Adults With Type 1 Diabetes on Ultra-Long-Acting Basal Insulin: A Randomized, Open-Label, Crossover Proof-of-Principle Study

OBJECTIVE

While the adjustment of insulin is an established strategy to reduce the risk of exercise-associated hypoglycemia for individuals with type 1 diabetes, it is not easily feasible for those treated with ultra-long-acting basal insulin. The current study determined whether pre-exercise intake of fructose attenuates the risk of exercise-induced hypoglycemia in individuals with type 1 diabetes using insulin degludec.

RESEARCH DESIGN AND METHODS

Fourteen male adults with type 1 diabetes completed two 60-min aerobic cycling sessions with or without prior intake (30 min) of 20 g of fructose, in a randomized two-period crossover design. Exercise was performed in the morning in a fasted state without prior insulin reduction and after 48 h of standardized diet. The primary outcome was time to hypoglycemia (plasma glucose ≤3.9 mmol/L) during exercise.

RESULTS

Intake of fructose resulted in one hypoglycemic event at 60 min compared with six hypoglycemic events at 27.5 ± 9.4 min of exercise in the control condition, translating into a risk reduction of 87.8% (hazard ratio 0.12 [95% CI 0.02, 0.66]; P = 0.015). Mean plasma glucose during exercise was 7.3 ± 1.4 mmol/L with fructose and 5.5 ± 1.1 mmol/L in the control group (P < 0.001). Lactate levels were higher at rest in the 30 min following fructose intake (P < 0.001) but were not significantly different from the control group during exercise (P = 0.32). Substrate oxidation during exercise did not significantly differ between the conditions (P = 0.73 for carbohydrate and P = 0.48 for fat oxidation). Fructose was well tolerated.

CONCLUSIONS

Pre-exercise intake of fructose is an easily feasible, effective, and well-tolerated strategy to alleviate the risk of exercise-induced hypoglycemia while avoiding hyperglycemia in individuals with type 1 diabetes on ultra-long-acting insulin.

A Prospective, Randomized Trial Testing Different Regimens of Carbohydrate Administration to Prevent Major Reduction in Plasma Glucose Follwing a Standardized Bout of Moderate Physical Activity in Patients with Type 1 Diabetes

AIM/HYPOTHESIS

It was the aim to prospectively study regimes of "preventive" carbohydrate administration to avoid major reduction in plasma glucose during physical activity.

METHODS

24 patients with type 1 diabetes (age 41±12 years; 11 women, 13 men; BMI 26.5±4.7 kg/m²; HbA_1c 9.1±1.5%; insulin dose 0.64±0.22 IU/kg body weight and day) participated in one experiment without physical activity and in three experiments with a 4 km, 60 min hike starting at 2 p.m.. No "preventive" carbohydrates, 2×10 g or 2×20 g carbohydrates (muesli bars) were taken when starting and after 30 min (randomized order). Plasma glucose was determined.

RESULTS

Within 30 min after starting physical activity, plasma glucose fell by approximately 70 mg/dl, making additional carbohydrate intake necessary in 70% of the subjects. This drop was not prevented by any regimens of "preventive" carbohydrate intake. After the nadir, plasma glucose rose faster after the 2×20 g carbohydrate regime (the largest amount tested; p=0.0036). With "preventive" administration of carbohydrates, significantly (p<0.05) less additional "therapeutic" carbohydrates needed to be administered in 6 h following the initiation of the hike.

CONCLUSIONS/INTERPRETATION

In conclusion, in the setting of 2 h postprandial exercise in type 1 diabetes, preventive carbohydrate supplementation alone will not completely eliminate the risk of brisk falls in plasma glucose concentrations or hypoglycaemic episodes. Else, higher amounts or repeated administration of carbohydrates may be necessary.

Similar cardiovascular and autonomic responses in trained type 1 diabetes mellitus and healthy participants in response to half marathon

AIMS

This field experiment examined whether trained people with type 1 diabetes mellitus (T1D) have similar cardiovascular and baroreflex alterations after a 21-km running race when compared to healthy people.

METHODS

Nine T1D (39.0 ± 11.1 yr; 175.0 ± 10.2 cm; 70.8 ± 8.7 kg) were matched with 9 healthy participants (42.4 ± 5.8 yr; 175.7 ± 6.7 cm; 72.1 ± 8.5 kg) who ran an official half-marathon. Before and 1-hour after the race, cardiovascular variables, sympathetic activity (catecholamines), parasympathetic (heart rate variability analysis) modulation and cardiac baroreflex function (transfer function analysis) were assessed during supine rest and a squat stand test (forced blood pressure change).

RESULTS

Performance time and weight loss [104.0 ± 13.2 and 111.0 ± 18.7 min; -2.57 ± 1.05 kg (-1.88 ± 0.88%) and -2.29 ± 1.15 kg (-1.59 ± 0.59%)] for healthy and T1D participants, respectively) were similar. Before running, no significant differences in any cardiovascular or autonomic variables were noted between the groups. After 1 h of recovery, both groups exhibited post-exercise hypotension, accompanied by increased sympathetic activity, decreased parasympathetic modulation, and reduced cardiac baroreflex sensitivity.

CONCLUSIONS

Our results showed that the pattern of change in cardiovascular and autonomic nervous activity to strenuous exercise are well maintained in T1D participants with a training history of at least 5 years.

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.

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.

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.

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.

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.

Acute bout of exercise induced prolonged muscle glucose transporter-4 translocation and delayed counter-regulatory hormone response in type 1 diabetes

Previous studies have demonstrated that an acute bout of aerobic exercise induces a subsequent delayed onset of hypoglycemia among patients with type 1 diabetes. However, the mechanisms of exercise-induced hypoglycemia in type 1 diabetes are still unclear. Streptozotocin (STZ) was injected to 6-week-old male Wistar rats, and three days after STZ injection, animals were randomly assigned into 2 groups: STZ with insulin only (STZ) and STZ with insulin and exercise (STZ+EX). Normal Wistar rats with exercise were used as control (CON+EX). Insulin was intraperitoneally injected (0.5 U/kg) to both STZ groups (-0.5 h), and a bout of aerobic exercise (15 m/min for 30 min) was conducted at euglycemic conditions (0 h). Blood was collected at 0, 1, 3, and 5 h after exercise from the carotid artery. While the blood glucose level was stable during the post-exercise period (0-5 h) in the STZ and CON+EX groups, it decreased significantly only in the STZ+EX group at 3 h. Plasma glucagon, adrenalin, and noradrenalin levels significantly increased at 1 h in the STZ group, whereas significant hormonal responses were observed at 5 h in the STZ+EX group. In skeletal muscle glucose metabolism-related pathway, the level of glucose transporter-4 (GLUT-4) translocation was significantly higher at 1 h in the CON and STZ groups. However, in the STZ+EX group, these activations were maintained by 5 h, indicating a sustained glucose metabolism in the STZ+EX group. A single bout of aerobic exercise induced a delayed onset of hypoglycemia in STZ-treated rats. A prolonged enhancement of GLUT-4 translocation and delayed counter-regulatory hormone responses may have contributed to the induction of hypoglycemia.

Effectiveness of SmartGuard Technology in the Prevention of Nocturnal Hypoglycemia After Prolonged Physical Activity

BACKGROUND

The prevention of postexercise nocturnal hypoglycemia after prolonged physical activity using sensor-augmented pump (SAP) therapy with predictive low-glucose management (PLGM) has not been well studied. We conducted a study at a pediatric diabetes camp to determine whether a SAP with PLGM reduces the frequency of nocturnal hypoglycemia after prolonged physical activity more effectively than a SAP with a carbohydrate intake algorithm.

METHODS

During a 1-week sport camp, 20 children (aged 10-13 years) with type 1 diabetes (T1D) managed by SAP therapy either with (n = 7) or without PLGM (n = 13) were studied. The hypoglycemia management strategy and the continuous glucose monitoring (CGM)/PLGM settings were standardized. The incidence, severity, and duration of hypoglycemia and carbohydrate intake were documented and compared.

RESULTS

The PLGM system was activated on 78% of all nights (once per night on average). No difference was found between the SAP and PLGM groups in the mean overnight glucose curve or mean morning glucose (7.8 ± 2 mmol/L vs. 7.4 ± 3 mmol/L). There was no difference in the frequency and severity of hypoglycemia. However, the SAP group consumed significantly more carbohydrates to prevent and treat hypoglycemia than those in the PLGM group; the values were 10 ± 2 and 1 ± 2 gS (P < 0.0001) in the SAP and PLGM groups, respectively. Moreover, the SAP group spent a significantly longer time in hypoglycemia (64 ± 2 min vs. 38 ± 2 min, P < 0.05). We observed a difference in the time distribution of nocturnal hypoglycemia (10 to 12 p.m. in the PLGM group and 3 to 7 a.m. in the SAP group, P < 0.05).

CONCLUSION

With PLGM system, euglycemia after prolonged physical activity was largely maintained with a minimal carbohydrate intake.

Metabolic Effects of Glucose-Fructose Co-Ingestion Compared to Glucose Alone during Exercise in Type 1 Diabetes

This paper aims to compare the metabolic effects of glucose-fructose co-ingestion (GLUFRU) with glucose alone (GLU) in exercising individuals with type 1 diabetes mellitus. Fifteen male individuals with type 1 diabetes (HbA1c 7.0% ± 0.6% (53 ± 7 mmol/mol)) underwent a 90 min iso-energetic continuous cycling session at 50% VO_2max while ingesting combined glucose-fructose (GLUFRU) or glucose alone (GLU) to maintain stable glycaemia without insulin adjustment. GLUFRU and GLU were labelled with ¹³C-fructose and ¹³C-glucose, respectively. Metabolic assessments included measurements of hormones and metabolites, substrate oxidation, and stable isotopes. Exogenous carbohydrate requirements to maintain stable glycaemia were comparable between GLUFRU and GLU (p = 0.46). Fat oxidation was significantly higher (5.2 ± 0.2 vs. 2.6 ± 1.2 mg·kg⁻¹·min⁻¹, p < 0.001) and carbohydrate oxidation lower (18.1 ± 0.8 vs. 24.5 ± 0.8 mg·kg⁻¹·min⁻¹p < 0.001) in GLUFRU compared to GLU, with decreased muscle glycogen oxidation in GLUFRU (10.2 ± 0.9 vs. 17.5 ± 1.0 mg·kg⁻¹·min⁻¹, p < 0.001). Lactate levels were higher (2.2 ± 0.2 vs. 1.8 ± 0.1 mmol/L, p = 0.012) in GLUFRU, with comparable counter-regulatory hormones between GLUFRU and GLU (p > 0.05 for all). Glucose and insulin levels, and total glucose appearance and disappearance were comparable between interventions. Glucose-fructose co-ingestion may have a beneficial impact on fuel metabolism in exercising individuals with type 1 diabetes without insulin adjustment, by increasing fat oxidation whilst sparing glycogen.

Strategies used by Patients with Type 1 Diabetes to Avoid Hypoglycemia in a 24×1-Hour Marathon: Comparison with the Amounts of Carbohydrates Estimated by a Customizable Algorithm

OBJECTIVES

The preferred countermeasure to avoid exercise-related hypoglycemia was investigated in a group of patients with type 1 diabetes participating in a stressful event, a 24×1-hour relay marathon. The carbohydrates actually consumed were compared to those estimated for each patient by applying a customizable algorithm, Exercise Carbohydrates Requirement Estimating Software (ECRES), based on patient's usual therapy and diet and on the exercise characteristics.

METHODS

Glycemia was tested at the start, middle and end of the races. Usual therapies and diets and the adopted countermeasures were recorded in detail.

RESULTS

We studied 19 patients who walked/ran 10.4±2.8 km with a heart rate of 167±11 beats per minute. Of the 19 patients, 7 patients reduced the administered insulin (premeal bolus or basal infusion rate). Glycemia fell by the end of the races (p=0.006; median -1.8 mmol⋅L^-1; interquartile range -0.4 mmol⋅L^-1 to -5.3 mmol⋅L^-1), despite 9 patients being hyperglycemic at the start. Of the patients, 14 concluded the race with glycemia on target, and 4 patients were hyperglycemic. Amounts of carbohydrates actually consumed (median 30 g; interquartile range 0 g to 71 g) were not significantly different from those estimated by ECRES (median 38 g; interquartile range 24 g to 68 g), the 2 quantities being significantly related (R=0.64; p=0.003). ECRES estimated lower carbohydrate levels (-13 g) than the amounts actually consumed by the 4 patients who concluded their exercises with hyperglycemia.

CONCLUSIONS

Patients preferred to consume extra carbohydrates to avoid the possible exercise-induced hypoglycemia. ECRES would provide satisfactory estimates of the carbohydrate requirements, even for a stressful condition, and almost equal to the quantities consumed following medical advice.

Diabetes and Sports: Managing Your Athlete With Type 1 Diabetes

More than 29 million people in the United States have diabetes mellitus, including both type 1 and type 2 diabetes. The CDC also estimates that upward of 86 million people can be classified as prediabetic, with as many as 30% of these people transitioning into diabetes within the next 5 years. Individuals with type 1 diabetes account for roughly 5% of those patients. Dating back to 2008 and 2009, roughly 18 000 youth were diagnosed with type 1 diabetes each year. The prevalence of diabetes is well known; most of the studies that are completed today relate to the progression and/or treatment of those with type 2 diabetes. Yet most physicians will have to take care of a type 1 diabetic patient who will want to be active. Having a fundamental knowledge of how exercise affects insulin and blood glucose and how to manage these patients is important. Time must be taken to modify each treatment regimen for each individual. One cannot stress enough the importance of providing patient education, ensuring adequate hydration, recognizing signs and symptoms of hypoglycemia/hyperglycemia, and how to treat and prevent these serious complications. All patients must have a care plan and access to supplies during exercise. It is known that poorly controlled blood glucose can have detrimental consequences in the long term. The question is if type I diabetic athletes who are allowed to have higher blood glucose during exercise are at the same risk for these potential complications.

Care of the Athlete With Type 1 Diabetes Mellitus: A Clinical Review

CONTEXT

Type 1 diabetes mellitus (T1DM) results from a highly specific immune-mediated destruction of pancreatic β cells, resulting in chronic hyperglycemia. For many years, one of the mainstays of therapy for patients with T1DM has been exercise balanced with appropriate medications and medical nutrition. Compared to healthy peers, athletes with T1DM experience nearly all the same health-related benefits from exercise. Despite these benefits, effective management of the T1DM athlete is a constant challenge due to various concerns such as the increased risk of hypoglycemia. This review seeks to summarize the available literature and aid clinicians in clinical decision-making for this patient population.

EVIDENCE ACQUISITION

PubMed searches were conducted for "type 1 diabetes mellitus AND athlete" along with "type 1 diabetes mellitus AND exercise" from database inception through November 2015. All articles identified by this search were reviewed if the article text was available in English and related to management of athletes with type 1 diabetes mellitus. Subsequent reference searches of retrieved articles yielded additional literature included in this review.

RESULTS

The majority of current literature available exists as recommendations, review articles, or proposed societal guidelines, with less prospective or higher-order treatment studies available. The available literature is presented objectively with an attempt to describe clinically relevant trends and findings in the management of athletes living with T1DM.

CONCLUSIONS

Managing T1DM in the context of exercise or athletic competition is a challenging but important skill for athletes living with this disease. A proper understanding of the hormonal milieu during exercise, special nutritional needs, glycemic control, necessary insulin dosing adjustments, and prevention/management strategies for exercise-related complications can lead to successful care plans for these patients. Individualized management strategies should be created with close cooperation between the T1DM athlete and their healthcare team (including a physician and dietitian).

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

AIMS

To validate strategies to prevent exercise-induced hypoglycaemia via insulin-dose adjustment in adult patients with type 1 diabetes (T1D) on pump therapy.

METHODS

A total of 20 patients randomly performed four 30-min late post-lunch (3 h after lunch) exercise sessions and a rest session: two moderate sessions [50% maximum oxygen consumption (VO2 max)] with 50 or 80% basal rate (BR) reduction during exercise + 2 h and two intense sessions (75% VO2 max) with 80% BR reduction or with their pump stopped. Two additional early post-lunch sessions (90 min after lunch) were analysed to compare hypoglycaemia incidence for BR reduction versus bolus reduction.

RESULTS

In all, 100 late post-lunch sessions were analysed. Regardless of exercise type and BR reduction, no more hypoglycaemic events occurred in the period until the next morning than occurred after the rest sessions. In the afternoon, no more hypoglycaemic events occurred with 80% BR reduction/moderate exercise or with pump discontinuation/intense exercise than for the rest session, whereas more hypoglycaemic events occurred with 50% BR reduction/moderate exercise and 80% BR reduction/intense exercise. After early post-lunch exercise (n = 37), a trend towards fewer hypoglycaemic episodes was observed with bolus reduction versus BR reduction (p = 0.07). Mean blood glucose fell by ∼3.3 mmol/l after 30 min of exercise, irrespective of dose reduction, remaining stable until the next morning with no rebound hyperglycaemia.

CONCLUSION

In adults with T1D, to limit the hypoglycaemic risk associated with 30 min of exercise 3 h after lunch, without carbohydrate supplements, the best options seem to be to reduce BR by 80% or to stop the pump for moderate or intense exercise, or for moderate exercise 90 min after lunch, to reduce the prandial bolus rather than the BR.

[Clinical recommendations for sport practice in diabetic patients (RECORD Guide). Diabetes Mellitus Working Group of the Spanish Society of Endocrinology and Nutrition (SEEN)]

Sporting activity is becoming a common practice in patients with diabetes mellitus (DM). This situation requires both a preliminary medical assessment and a wide range of changes in treatment which have scarcely been addressed in medical literature.

OBJECTIVE

To prepare a clinical guideline on the medical approach to patients with diabetes who practice sport regularly.

METHODS

An expert panel from the Diabetes Mellitus Working Group of the Spanish Society of Endocrinology and Nutrition (SEEN) reviewed the most relevant literature in each of the sections. Based both on this review and on data from the experience of a number of athletes with DM, a number of recommendations were agreed within each section. Finally, the Working Group and representatives of the SEEN jointly discussed all these recommendations.

CONCLUSION

The guideline provides recommendations ranging from medical assessment before patients with DM start to practice sport to actions during and after physical activity. Recommendations are also given on aspects such as the impact of sport on blood glucose control, training schemes, or special risk situations.

Prolonged exercise in type 1 diabetes: performance of a customizable algorithm to estimate the carbohydrate supplements to minimize glycemic imbalances

Physical activity in patients with type 1 diabetes (T1DM) is hindered because of the high risk of glycemic imbalances. A recently proposed algorithm (named Ecres) estimates well enough the supplemental carbohydrates for exercises lasting one hour, but its performance for prolonged exercise requires validation. Nine T1DM patients (5M/4F; 35–65 years; HbA1c 54±13 mmol·mol^-1) performed, under free-life conditions, a 3-h walk at 30% heart rate reserve while insulin concentrations, whole-body carbohydrate oxidation rates (determined by indirect calorimetry) and supplemental carbohydrates (93% sucrose), together with glycemia, were measured every 30 min. Data were subsequently compared with the corresponding values estimated by the algorithm. No significant difference was found between the estimated insulin concentrations and the laboratory-measured values (p = NS). Carbohydrates oxidation rate decreased significantly with time (from 0.84±0.31 to 0.53±0.24 g·min^-1, respectively; p<0.001), being estimated well enough by the algorithm (p = NS). Estimated carbohydrates requirements were practically equal to the corresponding measured values (p = NS), the difference between the two quantities amounting to –1.0±6.1 g, independent of the elapsed exercise time (time effect, p = NS). Results confirm that Ecres provides a satisfactory estimate of the carbohydrates required to avoid glycemic imbalances during moderate intensity aerobic physical activity, opening the prospect of an intriguing method that could liberate patients from the fear of exercise-induced hypoglycemia.

Oxidative stress in patients with type 1 diabetes mellitus: is it affected by a single bout of prolonged exercise?

Presently, no clear-cut guidelines are available to suggest the more appropriate physical activity for patients with type 1 diabetes mellitus due to paucity of experimental data obtained under patients' usual life conditions. Accordingly, we explored the oxidative stress levels associated with a prolonged moderate intensity, but fatiguing, exercise performed under usual therapy in patients with type 1 diabetes mellitus and matched healthy controls. Eight patients (4 men, 4 women; 49±11 years; Body Mass Index 25.0±3.2 kg·m⁻²; HbA_1c 57±10 mmol·mol⁻¹) and 14 controls (8 men, 6 women; 47±11 years; Body Mass Index 24.3±3.3 kg·m⁻²) performed a 3-h walk at 30% of their heart rate reserve. Venous blood samples were obtained before and at the end of the exercise for clinical chemistry analysis and antioxidant capacity. Capillary blood samples were taken at the start and thereafter every 30 min to determine lipid peroxidation. Patients showed higher oxidative stress values as compared to controls (95.9±9.7 vs. 74.1±12.2 mg·L⁻¹ H₂O₂; p<0.001). In both groups, oxidative stress remained constant throughout the exercise (p = NS), while oxidative defence increased significantly at the end of exercise (p<0.02) from 1.16±0.13 to 1.19±0.10 mmol·L⁻¹ Trolox in patients and from 1.09±0.21 to 1.22±0.14 mmol·L⁻¹ Trolox in controls, without any significant difference between the two groups. Oxidative stress was positively correlated to HbA_1c (p<0.005) and negatively related with uric acid (p<0.005). In conclusion, we were the first to evaluate the oxidative stress in patients with type 1 diabetes exercising under their usual life conditions (i.e. usual therapy and diet). Specifically, we found that the oxidative stress was not exacerbated due to a single bout of prolonged moderate intensity aerobic exercise, a condition simulating several outdoor leisure time physical activities. Oxidative defence increased in both patients and controls, suggesting beneficial effects of prolonged aerobic fatiguing exercise.

Exercise and type 1 diabetes (T1DM)

Physical exercise is firmly incorporated in the management of type 1 diabetes (T1DM), due to multiple recognized beneficial health effects (cardiovascular disease prevention being preeminent). When glycemic values are not excessively low or high at the time of exercise, few absolute contraindications exist; practical guidelines regarding amount, type, and duration of age-appropriate exercise are regularly updated by entities such as the American Diabetes Association and the International Society for Pediatric and Adolescent Diabetes. Practical implementation of exercise regimens, however, may at times be problematic. In the poorly controlled patient, specific structural changes may occur within skeletal muscle fiber, which is considered by some to be a disease-specific myopathy. Further, even in well-controlled patients, several homeostatic mechanisms regulating carbohydrate metabolism often become impaired, causing hypo- or hyperglycemia during and/or after exercise. Some altered responses may be related to inappropriate exogenous insulin administration, but are often also partly caused by the "metabolic memory" of prior glycemic events. In this context, prior hyperglycemia correlates with increased inflammatory and oxidative stress responses, possibly modulating key exercise-associated cardio-protective pathways. Similarly, prior hypoglycemia correlates with impaired glucose counterregulation, resulting in greater likelihood of further hypoglycemia to develop. Additional exercise responses that may be altered in T1DM include growth factor release, which may be especially important in children and adolescents. These multiple alterations in the exercise response should not discourage physical activity in patients with T1DM, but rather should stimulate the quest for the identification of the exercise formats that maximize beneficial health effects.

Whole-body glucose oxidation rate during prolonged exercise in type 1 diabetic patients under usual life conditions

OBJECTIVE

Fuel oxidation during exercise was studied in type 1 insulin-dependent (T1DM) patients mainly under quite constant insulin and glycemia; these protocols, however, likely do not reflect patients' usual metabolic conditions. The glucose oxidation rate (GLUox) in T1DM patients under usual life conditions was thus investigated during prolonged exercise (3-h) and its behavior was described mathematically.

MATERIALS/METHODS

Whole-body GLUox was determined in eight T1DM patients (4/8 M; aged 35-59 years) and eight well-matched healthy subjects. Venous blood was drawn prior to and every 30 min until the end of exercise; glycemia, insulin, cortisol, and growth hormone concentrations were determined. Oxygen consumption, carbon dioxide production, and ventilation were measured at rest and thereafter every 30 min of the exercise. To prevent hypoglycemia, patients were given fruit fudge (93% sucrose) prior to / during exercise.

RESULTS

Insulin concentration and glycemia were significantly higher in patients across the entire exercise period (group effect, p<0.001 for both). GLUox decreased significantly with increasing exercise duration (time effect, p<0.001), but no significant difference was detected between the two groups (group effect, p=NS). GLUox, expressed as the percentage of the starting value, was described by an exponential function showing a time constant of 90 min (n=96; mean corrected R(2)=0.666).

CONCLUSIONS

GLUox in T1DM patients was not significantly different from the rate observed in the control subjects. The function describing the time course of GLUox may be useful to correct an estimated GLUox for the duration of exercise and help T1DM patients avoiding exercise-induced glycemic imbalances.

Type 1 diabetes: dealing with physical activity

AIM

For patients with type 1 diabetes (T1D) using multiple insulin injections (MII), there are currently no guidelines for insulin dose adjustments in the event of physical activity (PA) and no simple algorithms that can be applied directly. Thus, the objective of this study was to assess the relevance of simple algorithms based on assessments of PA intensity by T1D patients themselves.

METHODS

This 4-month observational study was conducted in 35 patients using the Diabeo software system. Algorithms for insulin dose adjustments aimed to reduce the insulin dose of the meal closest to PA by 30 and 50% for moderate and intense PA, respectively. A 50% reduction plus extra carbohydrates was proposed for intense PA of long duration. These algorithms were entered into the Diabeo system.

RESULTS

The mean blood glucose (BG) profile in the event of PA (n = 151 triple BG values) was compared with that when no PA was performed (n = 3606). The initial mean FBG values were similar in both groups (7.58 ± 2.70 mmol/L vs. 7.80 ± 3.49 mmol/L; P = 0.36), whereas there was a slight, but significant, increase in 2-hours postprandial BG (PPBG) values related to PA, with a return to similar values before the next meal. The incidence of mild hypoglycaemia was similar, whether PA was undertaken or not, for the 2-hour PPBG and the next fasting/premeal glucose values.

CONCLUSION

This appears to be a pragmatic and efficient method for T1D patients using MII to adjust insulin doses in the event of PA that only requires an assessment of PA intensity by the patients themselves to anticipate the magnitude of the reduction in insulin doses.

Managing blood glucose during and after exercise in Type 1 diabetes: reproducibility of glucose response and a trial of a structured algorithm adjusting insulin and carbohydrate intake

AIMS AND OBJECTIVES

To enable people with Type 1 diabetes to exercise safely by investigating the reproducibility of the glucose response to an algorithm for carbohydrate and insulin adjustment during and after exercise compared to their self-management strategies.

BACKGROUND

Difficulties in managing blood glucose levels in Type 1 diabetes whilst exercising is known to deter people from exercise. Currently there is a limited evidence base to aid health care professionals enable people with diabetes to exercise safely. This study seeks to address this gap.

DESIGN

A quasi-experimental study was undertaken amongst people with Type 1 diabetes.

METHODS

Over 14 days, 14 participants undertook four exercise sessions (40 minutes at 50%VO2max). Two sessions were undertaken in week 1 self-managing their diabetes and two sessions in week 2 using an algorithm for carbohydrate and insulin adjustment.

RESULTS

The mean reduction of glucose levels detected by Continuous Glucose Monitoring during exercise was 3·1 (SD 2·03) mmol/l. Time spent within the range of 4-9 mmol/l during exercise was not significantly different between the self-managed and the algorithm weeks (-3-22·4 min). The mean reduction of blood glucose for each individual over all four exercise sessions ranged between 0·8-5·95 mmol/l. The technical error between days one and two was 2·4 mmol/l (CV=33·2%) and between days 3-4 the technical error was 2·7 mmol/l (CV=33·7%).

CONCLUSIONS

The results provide useful data about the reproducibility of the blood glucose response to moderate intensity exercise, despite the variability of individual responses 40 minutes of moderate intensity exercise decreases Continuous Glucose Monitoring glucose by 3 mmol/l with or without a 30% decrease of insulin before exercise.

RELEVANCE TO CLINICAL PRACTICE

This information provides valuable baseline information for people with diabetes and health care professionals who wish to encourage physical activity and undertake further research in this area.

Exercise and glycemic imbalances: a situation-specific estimate of glucose supplement

PURPOSE

The purposes of this study were to describe a newly developed algorithm that estimates the glucose supplement on a patient- and situation-specific basis and to test whether these amounts would be appropriate for maintaining blood glucose levels within the recommended range in exercising type 1 diabetic patients.

METHODS

The algorithm first estimates the overall amount of glucose oxidized during exercise on the basis of the patient's physical fitness, exercise intensity, and duration. The amount of supplemental CHO to be consumed before or during the effort represents a fraction of the burned quantity depending on the patient's usual therapy and insulin sensitivity and on the time of day the exercise is performed. The algorithm was tested in 27 patients by comparing the estimated amounts of supplemental CHO with the actual amounts required to complete 1-h constant-intensity walks. Each patient performed three trials, each of which started at different time intervals after insulin injection (81 walks were performed overall). Glycemia was tested every 15 min.

RESULTS

In 70.4% of the walks, independent of the time of day, the amount of CHO estimated by the algorithm would be adequate to allow the patients to complete the exercise with a glucose level within the selected thresholds (i.e., 3.9-10 mmol·L(-1)).

CONCLUSIONS

The algorithm provided a satisfactory estimate of the CHO needed to complete the exercises. Although the performance of the algorithm still requires testing for different exercise intensities, durations, and modalities, the results indicate its potential usefulness as a tool for preventing immediate exercise-induced glycemic imbalances (i.e., during exercise) in type 1 diabetic patients, in particular for spontaneous physical activities not planned in advance, thus allowing all insulin-dependent patients to safely enjoy the benefits of exercise.

Exercise-related hypoglycemia in diabetes mellitus

Current recommendations are that people with Type 1 and Type 2 diabetes mellitus exercise regularly. However, in cases in which insulin or insulin secretagogues are used to manage diabetes, patients have an increased risk of developing hypoglycemia, which is amplified during and after exercise. Repeated episodes of hypoglycemia blunt autonomic nervous system, neuroendocrine and metabolic defenses (counter-regulatory responses) against subsequent episodes of falling blood glucose levels during exercise. Likewise, antecedent exercise blunts counter-regulatory responses to subsequent hypoglycemia. This can lead to a vicious cycle, by which each episode of either exercise or hypoglycemia further blunts counter-regulatory responses. Although contemporary insulin therapies cannot fully mimic physiologic changes in insulin secretion, people with diabetes have several management options to avoid hypoglycemia during and after exercise, including regularly monitoring blood glucose, reducing basal and/or bolus insulin, and consuming supplemental carbohydrates.

Many patients with Type 1 diabetes estimate their prandial insulin need inappropriately

BACKGROUND

Many factors contribute to the need for prandial insulin in Type 1 diabetes. However, patients' success in achieving normal postprandial glucose concentration is understudied. The aim of the present study was to determine how often patients with Type 1 diabetes achieve normal postprandial glucose concentrations and to evaluate factors associated with postprandial hypo- and hyperglycemia.

METHODS

Data on food intake, physical activity, insulin administration, and blood glucose concentration were collected using a self-administered questionnaire from 331 patients with Type 1 diabetes (43% men; mean age 49 ± 12 years; mean diabetes duration 32 ± 13 years). Of these, 179 provided data on blood glucose concentrations measured 110-150 min postprandially. One such meal per patient was randomized for analyses.

RESULTS

Hypoglycemia (< 4.0 mmol/L), normoglycemia (4.0-7.9 mmol/L), and hyperglycemia (≥ 8.0 mmol/L) were observed after 23%, 36%, and 41% of meals, respectively. The three postprandial glycemia groups did not differ with respect to the meal composition or the timing of the postprandial blood glucose measurement. In women, postprandial hyperglycemia was associated with shorter diabetes duration and higher preprandial blood glucose concentration, whereas postprandial hypoglycemia was associated with higher physical activity. No single factor explained the postprandial glycemic state in men.

CONCLUSIONS

A total of 64% of patients estimated their prandial insulin need inappropriately, suggesting that estimation of the optimal prandial insulin dose is not easy, even after a long duration of diabetes.

Risks of marathon running and hypoglycaemia in Type 1 diabetes

BACKGROUND

Exercise-induced hypoglycaemia is common in people with insulin-treated diabetes and if severe can provoke neurological morbidity including coma and seizures. Depending on the duration and demands of the physical activity, various strategies can be used to limit the risk of hypoglycaemia with strenuous exercise. However, metabolic events occurring in the 48 h before the exercise can influence the risk and responses to exercise-induced hypoglycaemia.

CASE REPORT

A 27-year-old man with Type 1 diabetes suffered an episode of nocturnal hypoglycaemia which provoked a tonic-clonic seizure. Despite this he ran in a marathon the following day during which he collapsed with severe hypoglycaemia and a further associated seizure. He subsequently developed severe myalgia accompanied by a pronounced and persistent elevation of plasma creatine kinase, indicating rhabdomyolysis, and deranged liver function, suggestive of hypoxic hepatitis. The biochemical abnormalities and symptoms lasted for several weeks.

CONCLUSIONS

The case highlights the dangers of intense and prolonged physical exercise following severe hypoglycaemia, demonstrating the risks of acute damage to skeletal muscle and to organs such as the liver, in addition to the risk of severe neuroglycopenia and the induction of seizures. The mechanisms underlying these problems are discussed. People with insulin-treated diabetes should be advised not to undertake prolonged intensive exercise after severe hypoglycaemia.

Diabetes in sports

CONTEXT

Exercise is recommended for individuals with diabetes mellitus, and several facets of the disease must be considered when managing the diabetic athlete. The purpose of this article is to review diabetes care in the context of sports participation.

EVIDENCE ACQUISITION

Relevant studies were identified through a literature search of MEDLINE and the Cochrane database, as well as manual review of reference lists of identified sources.

RESULTS

Diabetics should be evaluated for complications of long-standing disease before beginning an exercise program, and exercise should be modified appropriately if complications are present. Athletes who use insulin or oral insulin secretogogues are at risk for exercise-induced immediate or delayed hypoglycemia. Diabetics are advised to engage in a combination of regular aerobic and resistance exercise. Insulin-dependent diabetics should supplement carbohydrate before and after exercise, as well as during exercise for events lasting longer than 1 hour. Adjustment of insulin dosing based on planned exercise intensity is another strategy to prevent hypoglycemia. Insulin-dependent athletes should monitor blood sugar closely before, during, and after exercise. Significant hyperglycemia before exercise should preclude exercise because the stress of exercise can paradoxically exacerbate hyperglycemia and lead to ketoacidosis. Athletes should be aware of hypoglycemia symptoms and have rapidly absorbable glucose available in case of hypoglycemia.

CONCLUSION

Exercise is an important component of diabetes treatment, and most people with diabetes can safely participate in sports at recreational and elite levels with attention to appropriate precautions.

The daily management of athletes with diabetes

The unique demands of exercise and competition can predispose diabetic athletes to harmful complications. A basic understanding of glucose metabolism during exercise, nutritional adequacy, blood glucose control, medications, and management of on-field complications is important for medical personnel who care for diabetic athletes on a daily basis. Diabetic athletes are best managed by "individualized"" preventive and treatment algorithms that should be developed by a team of medical professionals including the athletic trainer, sports nutritionist, and physician.

Exercise and glycemic control in diabetes: benefits, challenges, and adjustments to pharmacotherapy

Exercise, along with dietary intervention, represents first-line therapy for diabetes mellitus. Aerobic exercise is recommended for its beneficial effects on glucose control as well as its abilities to retard the progression of other comorbidities common in patients with diabetes, such as cardiovascular disease. The capability of aerobic exercise to improve glycemic control in diabetes is well documented, although adherence to exercise regimens is problematic. More recently, the glucose-lowering effects of resistance training have also been documented; this form of exercise has additional benefits, such as the capability to counteract sarcopenia, which is common in older people with type 2 diabetes. Exercise in people with diabetes, however, also can present significant challenges to glycemic control. Excessive glucose lowering can occur under certain conditions, enhancing the threat of hypoglycemia; in other situations, hyperglycemia can be accentuated. An understanding of the interactions between specific antidiabetic medications and various forms and intensities of exercise is essential to optimizing glycemic control while minimizing the potential for acute derangements in plasma glucose levels. Exogenous forms of insulin and agents that stimulate insulin secretion in a glucose-independent manner (such as sulfonylureas and glinides) increase the propensity for hypoglycemia during low- to moderate-intensity aerobic exercise. In contrast, exercise protocols characterized by high intensity are more likely to result in episodes of hyperglycemia. Strategies to minimize inappropriate swings in glycemic control are reviewed.

Fuel metabolism during exercise in euglycaemia and hyperglycaemia in patients with type 1 diabetes mellitus--a prospective single-blinded randomised crossover trial

AIMS/HYPOTHESIS

We assessed systemic and local muscle fuel metabolism during aerobic exercise in patients with type 1 diabetes at euglycaemia and hyperglycaemia with identical insulin levels.

METHODS

This was a single-blinded randomised crossover study at a university diabetes unit in Switzerland. We studied seven physically active men with type 1 diabetes (mean +/- SEM age 33.5 +/- 2.4 years, diabetes duration 20.1 +/- 3.6 years, HbA1c 6.7 +/- 0.2% and peak oxygen uptake [VO2peak] 50.3 +/- 4.5 ml min(-1) kg(-1)). Men were studied twice while cycling for 120 min at 55 to 60% of VO2peak, with a blood glucose level randomly set either at 5 or 11 mmol/l and identical insulinaemia. The participants were blinded to the glycaemic level; allocation concealment was by opaque, sealed envelopes. Magnetic resonance spectroscopy was used to quantify intramyocellular glycogen and lipids before and after exercise. Indirect calorimetry and measurement of stable isotopes and counter-regulatory hormones complemented the assessment of local and systemic fuel metabolism.

RESULTS

The contribution of lipid oxidation to overall energy metabolism was higher in euglycaemia than in hyperglycaemia (49.4 +/- 4.8 vs 30.6 +/- 4.2%; p < 0.05). Carbohydrate oxidation accounted for 48.2 +/- 4.7 and 66.6 +/- 4.2% of total energy expenditure in euglycaemia and hyperglycaemia, respectively (p < 0.05). The level of intramyocellular glycogen before exercise was higher in hyperglycaemia than in euglycaemia (3.4 +/- 0.3 vs 2.7 +/- 0.2 arbitrary units [AU]; p < 0.05). Absolute glycogen consumption tended to be higher in hyperglycaemia than in euglycaemia (1.3 +/- 0.3 vs 0.9 +/- 0.1 AU). Cortisol and growth hormone increased more strongly in euglycaemia than in hyperglycaemia (levels at the end of exercise 634 +/- 52 vs 501 +/- 32 nmol/l and 15.5 +/- 4.5 vs 7.4 +/- 2.0 ng/ml, respectively; p < 0.05).

CONCLUSIONS/INTERPRETATION

Substrate oxidation in type 1 diabetic patients performing aerobic exercise in euglycaemia is similar to that in healthy individuals revealing a shift towards lipid oxidation during exercise. In hyperglycaemia fuel metabolism in these patients is dominated by carbohydrate oxidation. Intramyocellular glycogen was not spared in hyperglycaemia.

Interventions for being active among individuals with diabetes: a systematic review of the literature

PURPOSE

The purpose of this systematic review is to assess and summarize evidence and gaps in the literature regarding the intervention for being active (exercise) among individuals with diabetes.

METHODS

Twelve electronic databases were searched. Publications eligible for inclusion specifically studied learning, behavioral, clinical, and humanistic outcomes for exercise interventions in adult patients with type 1 and type 2 diabetes.

RESULTS

Seven reviews (2 systematic reviews, 3 meta-analyses, 2 technical reviews) and 34 individual, nonreview studies (18 randomized controlled trials, 16 nonrandomized trials) met inclusion criteria. For type 2 diabetes, findings suggested that exercise had a positive effect on glycemic control and decreased cardiovascular risk, but the impact of exercise on behavioral and humanistic outcomes was unclear; long-term outcomes and adherence to exercise interventions is unknown because most studies were of short duration. The overall impact of varied types of exercise in type 1 diabetes was unclear, especially regarding glycemic control. Potential benefits of exercise in type 1 may include improved cardiovascular health.

CONCLUSION

The review did not identify specific successful intervention details because of the heterogeneity of studies, subjects, and research gaps. General findings suggest that physical activity is better than no exercise at all; intensive regimens, if tolerated by patients, achieved better clinical outcomes than less intensive regimens. Reviewed studies using structured exercise regimens exhibited a more significant impact on outcomes. Substantial gaps in the literature include studies measuring direct effects of exercise in the US minority populations most affected by type 2 diabetes and economic evaluations of exercise interventions. Interventions must be tailored to individual patient needs to succeed.