Diabetes management for intense exercise

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.

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.

US Army Soldiers With Type 1 Diabetes Mellitus

US Army soldiers diagnosed with type 1 diabetes were previously considered unfit for duty. For highly motivated soldiers, current advanced technologies allow the possibility of not only retention on active duty, but military deployment. We present our experience at Fort Bragg, North Carolina, taking care of soldiers newly diagnosed with type 1 diabetes mellitus. Through intensive diabetes education, extensive military and physical training, optimization of diabetes technology, and remote real-time monitoring, soldiers are able to continue to serve their country in the most specialized roles.

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

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

Biochemical, Physiological and Psychological Changes During Endurance Exercise in People With Type 1 Diabetes

BACKGROUND

Increasing numbers of people with diabetes are adopting exercise programs. Fear of hypoglycemia, hypoglycemia itself, and injuries are major issues for many people with diabetes undertaking physical activity. The purpose of this study was to investigate the effects of type 1 diabetes mellitus on the risk of hypoglycemia, glycemic variability, exercise performance, changes in body composition, changes in insulin dosage, and psychosocial well-being during a multiday endurance exercise event.

METHODS

Eleven participants (7 with type 1 diabetes, 4 with normal glucose tolerance) undertook a 15-day, 2300 km cycling tour from Barcelona to Vienna. Data were prospectively collected using bike computers, continuous glucose monitors, body composition analyzers, and mood questionnaires.

RESULTS

Mean blood glucose in riders with and without diabetes significantly reduced as the event progressed. Glycemic variability and time spent in hypoglycemia did not change throughout the ride for either set of riders. Riders with diabetes in the lowest quartile of sensor glucose values had significantly reduced power output. Percentage body fat also significantly fell. Hypo- and hyperglycemia provoked feelings of anxiety and worry.

CONCLUSIONS

This is the first study to describe a real-time endurance event in type 1 diabetes, and provides important new data that cannot be studied in laboratory conditions. Hypoglycemia continues to occurs in spite of peer support and large reductions in insulin dose. Glycemic variability is shown as a potential barrier to participation in physical activity through effects on mood and psychological well-being.

Special Considerations in Medical Screening for Participants in Remote Endurance Events

As participation at remote endurance events increases, so does the need to screen participants for potentially problematic medical conditions, but this process has been ill-defined to date. This article aims to outline a general approach to screening and discusses common or important medical conditions that may need consideration in the screening process. Medical conditions that are considered low risk may translate to high-risk conditions in the setting of a remote and austere location. Medical directors of remote endurance events should have a familiarity with assessing risks and applying informed consent principles to participation. While there are no specific standards on medical disqualification from an event based on medical history alone, several systematic considerations should be made that allow for an assessment of risk to an individual for a specific event. The medical director and event director, in discussion with the athlete and treating clinician when appropriate, should come to a consensus on participation when high-risk medical conditions become apparent during the screening process. Both modifications and accommodations to participation may be used to mitigate both clinical and medicolegal risk and allow for participation.

Managing collapsed or seriously ill participants of ultra-endurance events in remote environments

Increasing participation in ultramarathons and other ultra-endurance events amplifies the potential for serious medical issues during and immediately following these competitions. Since these events are often located in remote settings where access may be extremely limited; the diagnostic capabilities, treatment options, and expectations of medical care may differ from those of urban events. This work outlines a process for assessment and treatment of athletes presenting for medical attention in remote environments, with a focus on potentially serious conditions such as major trauma, acute coronary syndrome, exertional heat stroke, hypothermia, hypoglycemia, exercise-associated hyponatremic encephalopathy, severe dehydration, altitude illness, envenomation, anaphylaxis, and bronchospasm. A list of suggested medical supplies is provided and discussed. But, given that diagnostic and treatment options may be extremely limited in remote settings, it is important for medical providers to understand how to assess and manage the most common serious medical issues with limited resources, and to be prepared to make presumptive diagnoses when necessary.

Telemedicine in US Army soldiers with type 1 diabetes

A retrospective study of a telemedicine clinic for active duty US Army soldiers with type 1 diabetes was conducted. Fifty-one consecutive patients (mean age 33.9 years) were enrolled into the clinic. All soldiers with known or newly diagnosed type 1 diabetes received three weekly office visits for intensive diabetes education. After this, all communication occurred via a messaging system consisting of texting, web-based download, and/or email to a diabetes management team. For urgent matters, 24/7 direct paging or telephone access was provided. Routine adjustments in insulin dosing were accomplished via email. Soldiers were followed for a mean of 17.1 months. Baseline, three-month, and end of study glycated hemoglobin (A1C) values were 9.8, 7.3, and 6.9, respectively. There were no significant differences in end of study A1C levels between patients with known vs. newly diagnosed type 1 diabetes, nor were there any differences between those patients who received insulin via pump therapy vs. multiple daily injections. Telemedicine was safe and effective in lowering A1C levels in US Army soldiers with type 1 diabetes.

Comparison of appetite responses to high- and low-glycemic index postexercise meals under matched insulinemia and fiber in type 1 diabetes

BACKGROUND

Patients with type 1 diabetes face heightened risk of hypoglycemia after exercise. Subsequent overfeeding, as a preventative measure against hypoglycemia, negates the energy deficit after exercise. Patients are also required to reduce the insulin dose administered with postexercise foods to further combat hypoglycemia. However, the insulin dose is dictated solely by the carbohydrate content, even though postprandial glycemia is vastly influenced by glycemic index (GI). With a need to control the postexercise energy balance, appetite responses after meals differing in GI are of particular interest.

OBJECTIVES

We assessed the appetite response to low-glycemic index (LGI) and high-glycemic index (HGI) postexercise meals in type 1 diabetes patients. This assessment also offered us the opportunity to evaluate the influence of GI on appetite responses independently of insulinemia, which confounds findings in individuals without diabetes.

DESIGN

Ten physically active men with type 1 diabetes completed 2 trials in a randomized crossover design. After 45 min of treadmill exercise at 70% of the peak oxygen uptake, participants consumed an LGI (GI ∼37) or HGI (GI ∼92) meal with a matched macronutrient composition, negligible fiber content, and standardized insulin-dose administration. The postprandial appetite response was determined for 180 min postmeal. During this time, circulating glucose, insulin, glucagon, and glucagon-like peptide-1 (GLP-1) concentrations and subjective appetite ratings were determined.

RESULTS

The HGI meal produced an ∼60% greater postprandial glucose area under the curve (AUC) than did the LGI meal (P = 0.008). Insulin, glucagon, and GLP-1 did not significantly differ between trials (P > 0.05). The fullness AUC was ∼25% greater after the HGI meal than after the LGI meal (P < 0.001), whereas hunger sensations were ∼9% lower after the HGI meal than after the LGI meal (P = 0.001).

CONCLUSION

Under conditions of matched insulinemia and fiber, an HGI postexercise meal suppresses feelings of hunger and augments postprandial fullness sensations more so than an otherwise equivalent LGI meal in type 1 diabetes patients.

Moderate Intensity Training Impact on the Inflammatory Status and Glycemic Profiles in NOD Mice

The nonobese diabetic (NOD) mouse represents a well-established experimental model analogous to human type 1 diabetes mellitus (T1D) as it is characterized by progressive autoimmune destruction of pancreatic β-cells. Experiments were designed to investigate the impact of moderate-intensity training on T1D immunomodulation and inflammation. Under a chronic exercise regime, NOD mice were trained on a treadmill for 12 weeks (12 m/min for 30 min, 5 d/wk) while age-matched, control animals were left untrained. Prior to and upon completion of the training period, fed plasma glucose and immunological soluble factors were monitored. Both groups showed deteriorated glycemic profiles throughout the study although trained mice tended to be more compensated than controls after 10 weeks of training. An exercise-induced weight loss was detected in the trained mice with respect to the controls from week 6. After 12 weeks, IL-6 and MIP-1β were decreased in the trained animals compared to their baseline values and versus controls, although not significantly. Morphometric analysis of pancreata revealed the presence of larger infiltrates along with decreased α-cells areas in the control mice compared to trained mice. Exercise may exert positive immunomodulation of systemic functions with respect to both T1D and inflammation, but only in a stringent therapeutic window.

Diabetes and exercise

Exercise has a beneficial effect on metabolic parameters affecting cardiovascular risk, such as lipids and blood glucose, and is a key component in both the prevention and the management of type 2 diabetes. Glycaemic control improves with both aerobic and resistance exercise in type 2 diabetes, but no glycaemic benefit is seen in type 1 diabetes. This probably results from glucose fluctuations commonly seen with exercise. Low and moderate intensity exercise are generally associated with a fall in blood glucose, and high intensity exercise can be associated with a rise in blood glucose. Trial evidence is suggestive of a reduction in cardiovascular risk with exercise, although evidence from prospective, randomised controlled trials is certainly not conclusive.

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.

Hypoglycemia: The neglected complication

Hypoglycemia is an important complication of glucose-lowering therapy in patients with diabetes mellitus. Attempts made at intensive glycemic control invariably increases the risk of hypoglycemia. A six-fold increase in deaths due to diabetes has been attributed to patients experiencing severe hypoglycemia in comparison to those not experiencing severe hypoglycemia Repeated episodes of hypoglycemia can lead to impairment of the counter-regulatory system with the potential for development of hypoglycemia unawareness. The short- and long-term complications of diabetes related hypoglycemia include precipitation of acute cerebrovascular disease, myocardial infarction, neurocognitive dysfunction, retinal cell death and loss of vision in addition to health-related quality of life issues pertaining to sleep, driving, employment, recreational activities involving exercise and travel. There is an urgent need to examine the clinical spectrum and burden of hypoglycemia so that adequate control measures can be implemented against this neglected life-threatening complication. Early recognition of hypoglycemia risk factors, self-monitoring of blood glucose, selection of appropriate treatment regimens with minimal or no risk of hypoglycemia and appropriate educational programs for healthcare professionals and patients with diabetes are the major ways forward to maintain good glycemic control, minimize the risk of hypoglycemia and thereby prevent long-term complications.

Large pre- and postexercise rapid-acting insulin reductions preserve glycemia and prevent early- but not late-onset hypoglycemia in patients with type 1 diabetes

OBJECTIVE

To examine the acute and 24-h glycemic responses to reductions in postexercise rapid-acting insulin dose in type 1 diabetic patients.

RESEARCH DESIGN AND METHODS

After preliminary testing, 11 male patients (24 ± 2 years, HbA1c 7.7 ± 0.3%; 61 ± 3.4 mmol/mol) attended the laboratory on three mornings. Patients consumed a standardized breakfast (1 g carbohydrate · kg(-1) BM; 380 ± 10 kcal) and self-administered a 25% rapid-acting insulin dose 60 min prior to performing 45 min of treadmill running at 72.5 ± 0.9% VO2peak. At 60 min postexercise, patients ingested a meal (1 g carbohydrate · kg(-1) BM; 660 ± 21 kcal) and administered a Full, 75%, or 50% rapid-acting insulin dose. Blood glucose concentrations were measured for 3 h postmeal. Interstitial glucose was recorded for 20 h after leaving the laboratory using a continuous glucose monitoring system.

RESULTS

All glycemic responses were similar across conditions up to 60 min postexercise. After the postexercise meal, blood glucose was preserved under 50%, but declined under Full and 75%. Thence at 3 h, blood glucose was highest under 50% (50% [10.4 ± 1.2] vs. Full [6.2 ± 0.7] and 75% [7.6 ± 1.2 mmol · L(-1)], P = 0.029); throughout this period, all patients were protected against hypoglycemia under 50% (blood glucose ≤ 3.9; Full, n = 5; 75%, n = 2; 50%, n = 0). Fifty percent continued to protect patients against hypoglycemia for a further 4 h under free-living conditions. However, late-evening and nocturnal glycemia were similar; as a consequence, late-onset hypoglycemia was experienced under all conditions.

CONCLUSIONS

A 25% pre-exercise and 50% postexercise rapid-acting insulin dose preserves glycemia and protects patients against early-onset hypoglycemia (≤ 8 h). However, this strategy does not protect against late-onset postexercise hypoglycemia.

Practical aspects and considerations when switching between continuous subcutaneous insulin infusion and multiple daily injections

Insulin pump therapy is considered the gold standard for insulin management in patients requiring full physiologic insulin replacement. Compared to traditional delivery of short- and long-acting insulin preparations by multiple daily insulin injections, delivery of insulin via continuous subcutaneous infusion brings with it several advantages, which in the past have translated into better glycemic control and treatment satisfaction. Delivery of insulin via pump reduces the number needle insertions (from four or five per day to once every 2-3 days), allows for greater flexibility of insulin delivery with regard to both the basal and prandial component, facilitates portability of the insulin preparation, and allows for more accurate dosing. Continuous subcutaneous insulin infusion does have some drawbacks, including a greater risk of inadvertent insulin non-delivery, greater costs of therapy, and the need to be "tethered" with some systems that might be considered "burdensome" or even undesirable to some patients. For the most part patients who initiate insulin pump therapy are satisfied and continue using the technology, but there might be instances that arise that require the re-introduction of insulin delivery by pen or syringe. This article will review some of the reasons and strategies for switching from one mode of delivery to the other.

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.