Exercise in children and adolescents with diabetes

Abstract

In the 1950s, Joslin proposed that exercise is the third essential component in blood glucose regulation for persons with type 1 diabetes after insulin and dietary management. Although most studies have shown little impact upon hemoglobin A1c (HbA1c) levels (1–3) (B), the benefits of exercise go far wider: weight control, reduced cardiovascular risk, and an improved sense of well-being (4) (B). Postmeal exercise can be a valuable way to minimize postprandial glycemic spikes (E). For some, participation in physical activity is somewhat sporadic and related to leisure, school, or work. For others, daily exercise is a part of an overall training or conditioning program. Children and adolescents with diabetes should derive many of the same health and leisure benefits as adults and should be allowed to participate with equal opportunities and with equal safety. Diabetes should not limit the ability to excel in a chosen sport. Many famous athletes have proved this, e.g., Sir Steve Redgrave the five times Olympic gold medal winning rower, Gary Hall the US Olympic gold medal swimmer at Athens, Wasim Akram is a Pakistani cricketer at the international level, Major League baseball player Jason Johnson, Ironman triathlete Bill Carlson, and female pro golfer Mimmi Hjorth. The topic most commonly discussed with families with regard to exercise is avoidance of hypoglycemia, but prevention of acute hyperglycemia/ketoacidosis may become a concern as well (5) (C). While this chapter is intended to address the issue of blood glucose regulation during various forms of sports and exercise, it is important for diabetes professionals and parents to appreciate that the demands of day-to-day physical activity will also have to be considered if a young person is going to participate in any activity that for them is unusually strenuous or prolonged. Before considering the situation in type 1 diabetes, it is useful to understand the physiological response to moderate-intensity aerobic exercise in the non-diabetic individual. As shown in Fig. 1, non-diabetic individuals have a reduction in insulin secretion and an increase in glucose counter-regulatory hormones that facilitate an increase in liver glucose production, which matches skeletal muscle glucose uptake during exercise. As a result of this precise autonomic and endocrine regulation, blood glucose levels remain stable under most exercise conditions (4) (B). Physiologic responses to exercise in the diabetic and non-diabetic individual. Square brackets denote plasma concentration. In type 1 diabetes, the pancreas does not regulate insulin levels in response to exercise, and there may be impaired glucose counter-regulation, making normal fuel regulation nearly impossible. Hypoglycemia commonly occurs during exercise when insulin is administered prior to the start of the activity. In real life, young people with diabetes have variable blood glucose responses to exercise. The blood glucose response to 60 min of intermittent exercise is somewhat reproducible if the timing of exercise and the amount of insulin and the pre-exercise meal remain consistent (6) (B). Glucose production in healthy control subjects increases with exercise intensity and can be entirely attributed to increases in net hepatic glycogenolysis. In contrast, moderately controlled type 1 diabetic subjects exhibit increased rates of glucose production both at rest and during exercise, which can be entirely accounted for by increased gluconeogenesis (7) (B). Young people with type 1 diabetes have been found to have decreased aerobic capacity as measured by VO2 max compared with non-diabetic control subjects (8) (B). Total body insulin-mediated glucose metabolism in adolescents correlates with the degree of glycemic control as assessed by the level of glycosylated hemoglobin (9) (B). However, even in the same individual, it is possible for the blood glucose to be increased, decreased, or unchanged by exercise dependent upon circumstances as indicated in the Table 1. It is especially important to plan for long-duration or intense aerobic exercise, or else, hypoglycemia is almost inevitable. Nearly all forms of activity lasting >30 min will be likely to require some adjustment to food and/or insulin. Most team and field sports and also spontaneous play in children are characterized by repeated bouts of intensive activity interrupting longer periods of low to moderate-intensity activity or rest. This type of activity has been shown to produce a lesser fall in blood glucose levels compared with continuous moderate-intensity exercise, both during and after the physical activity in young adults (10) (B). The repeated bouts of high-intensity exercise stimulated higher levels of noradrenaline that increased blood glucose levels. Moderate-intensity exercise (40% of VO2 max) followed by an intense cycling sprint at maximal intensity prevented a further decline in blood glucose for at least 2 h after the exercise (11) (B). However, typical team games may last up to 90 min, and the results may not be applicable to this length of physical activity. Furthermore, the authors were unable to explain why the short sprint countered a fall in glucose levels for so long because the rise in catecholamines following the intense exercise was very short lived (see also Type of activity). Anaerobic efforts last only a short time (sometimes only seconds) but may increase the blood glucose level dramatically because of the release of the hormones adrenaline and glucagon. This rise in blood glucose is usually transient, lasting typically 30–60 min, and can be followed by hypoglycemia in the hours after finishing the exercise. Aerobic activities tend to lower blood glucose both during (usually within 20–60 min after the onset) and after the exercise (4) (B). Where control is poor and preexercise blood glucose level is high, circulating insulin levels may be inadequate and the effect of counter-regulatory hormones will be exaggerated leading to a higher likelihood of ketosis (E). High blood glucose has been found to reduce the secretion of beta-endorphins during exercise, which has been associated with an increased rating of perceived exertion (RPE) during leg exercise (12) (B). In fact, even baseline beta-endorphin levels were reduced in the diabetic subjects irrespective of blood glucose and thus the resultant reduced tolerance of discomfort may compromise exercise performance in individuals with diabetes. Similarly, increases were found in RPE in adolescents with diabetes doing whole-body exercise (13) (B), but the authors indicate that the higher response is thought to be mainly a function of the lower peak mechanical power output often seen in these patients (14). When regular (soluble) insulin has been injected prior to exercise, the most likely time for hypoglycemia will be 2–3 h after injection, and the high-risk time after rapid analogue insulin is between 40 and 90 min (15) (B). We have found no studies on the timing of basal insulins (NPH, glargine, or detemir) and exercise. When playing morning or all-day tournaments, a long-acting basal insulin given once daily in the evening can be substituted for one with shorter action (NPH) to reduce the basal insulin effect while exercising (E). A meal containing carbohydrates (CHO), fats, and protein should be consumed roughly 3–4 h prior to competition to allow for digestion and for a maximizing of endogenous energy stores. This is especially important for longer-duration activities. Glycogen stores can be enhanced with a carbohydrate beverage (1–2 g CHO/kg) approximately 1 h prior; this also helps to supplement energy stores and provide adequate fluids for hydration (16). If extra carbohydrate is necessary for short duration activity, then it may be useful to have ‘fast-acting’ carbohydrates such as glucose drinks. An isotonic beverage containing 6% simple sugar (i.e., sucrose, fructose, and glucose) provides optimal absorption compared with other more concentrated beverages with more than 8% glucose such as juice or carbonated drinks that delay gastric absorption and cause stomach upset (16). Check the glucose content of sport drinks, some contain >8% glucose. The amount of carbohydrate should be matched as closely as possible to the amount of carbohydrate utilized during exercise if a reduction in insulin is not performed. In general, approximately 1.0–1.5 g CHO/kg body weight/h should be consumed during exercise performed during peak insulin action in young adults with diabetes (16) (Table 2). Because insulin sensitivity remains elevated for hours postexercise, carbohydrate stores must be replenished quickly to lower the of hypoglycemia during the hours duration and high-intensity activities as weight and may not require carbohydrate prior to the activity, but may produce a in blood For activities of these extra carbohydrate after the activity is often the to hypoglycemia (E). lower intensity aerobic activities such as as a between aerobic and and will require extra carbohydrate and often after the activity (E). no on the amount and timing of increased carbohydrate to limit However, in basal low glycemic no or reduced at will usually reduce the (E). A of and protein at may limit hypoglycemia by exercise (B). of When an or has been injected with insulin and is then the increased blood to the is likely to result in more rapid absorption and effect of the insulin (B). This may be especially if the is a may more consistent response by to in an or the than a leg an High will increase insulin absorption and low the (B). The may be a in Most absorption studies were with regular insulin. The effect is with (C). An intense of exercise not increase the absorption of in adults with type 1 diabetes also on the cardiovascular in energy and for a in blood glucose levels. more a in blood and activities tend to more energy than activities. that the in blood glucose may be with regular conditioning and with the no that this The response will the blood glucose. activity, insulin may not result in hypoglycemia as circulating insulin levels are typically low and glucose counter-regulatory hormones may be may with exercise in these even physical activities should be a part of the normal for both health benefits and in blood glucose management. of and with diabetes have been found to be more than non-diabetic (C). and exercise is to because it is part of the but may also be necessary for sporadic extra physical activity. level of in exercise and sport that a or with diabetes it is that are of and intensity of physical carbohydrate has been and the blood glucose response and the diabetes team will be in the but will allow more and (E). Where exercise is performed insulin sensitivity is A between glycemic control (i.e., and aerobic or physical activity in with type 1 diabetes, that increased aerobic capacity may glycemic control or control exercise (8) (B). An was between level and the maximal in a in diabetic adolescents (B). The of on with exercise may be related to a to insulin and carbohydrate in an to hypoglycemia (B). The of diabetes may to the of training so that when is with long moderate-intensity the insulin and carbohydrate may be that when the is upon power and high-intensity the and intensity for more on the possible effect of high-intensity on enhanced muscle insulin sensitivity and increased of glucose (C). sensitivity was and h after exercise but decreased to levels after in non-diabetic adults and after exercise and h in the insulin sensitivity is elevated in adolescents with type 1 diabetes (B). In life, exercise for h can to increased insulin sensitivity for up to This that adolescents only exercise can have real in basal insulins (E). It is to exercise at least other if If a for basal insulins to with the insulin sensitivity is children most often exercise well to some which results in in blood glucose (E). with content of carbohydrates should be consumed after the exercise to of the of insulin sensitivity to content and limit However, the insulin will to be reduced to the normal for the to protein will (C). It is well the of this chapter to training but such is Diabetes and an international that provides and between health and diabetic a of and are with For most children and the of insulin will not be by exercise However, for some are it is likely that daily or insulin be considered to allow for in insulin prior to and following the activity. It may be to very blood glucose control on these especially with levels of exercise the but the essential of various forms of carbohydrate and after exercise may be even more important than for more insulin For a insulin is given then a insulin with rapid analogue evening meal and a insulin at this must be by carbohydrate for exercise, e.g., or or or at or insulin This for training and preexercise and basal rates can be reduced and after exercise to increase hepatic glucose production and limit hypoglycemia (see The of insulin is by many the of various insulins and and in the should be by the of the sport. is no that to reduce the training of h control of blood glucose more with the to periods in the and to the insulin (C). In the autonomic and counter-regulatory response to hypoglycemia the following has been shown to be by repeated or moderate-intensity exercise (B). The same is likely to be for Glucose to stable glucose levels in adolescents with diabetes are elevated during and after exercise as well as h after exercise (B). In repeated of hypoglycemia in a result in an counter-regulatory response to exercise and increase the for to times more glucose may be to during exercise following a to hypoglycemia (B). In studies of diabetic adolescents insulin and then performed on a hypoglycemia if blood glucose was In the same it was that g was to blood glucose to normal In (B), of children with type 1 diabetes blood glucose levels during 60 min of cycling performed in the carbohydrate glucose at a that carbohydrate during exercise g CHO/kg body the in blood glucose during exercise be If a with diabetes is during exercise with and of hypoglycemia, glucose or other of carbohydrate should be given as for of hypoglycemia, even if blood glucose be measured to hypoglycemia (E). or activity all the adults also should be to the of should be given that no person with diabetes should exercise or go or not to have regular when are A is that if young people with diabetes are on should in of at least so that can other if to to the of an or Glucose glucose or some of sugar should be by young people exercise at a within a of the activity. Hypoglycemia can hours after exercise especially when this has been and of or intensity (C). This is because of the effect of increased insulin sensitivity and delay in liver and muscle stores. A of exercise can increase glucose skeletal muscle for at least h in non-diabetic and diabetic subjects (B). In a controlled as many a on the after an exercise compared with the after a the basal insulin was not glucose may be a valuable for the blood glucose response and hypoglycemia during and after exercise athletes may be to reduce insulin to hypoglycemia, and control may as a result (B). and are In a of young people a sport of at least h of exercise a lower (C). In one with type 1 diabetes were to on for hours hypoglycemia when the by compared with only 90 min if the was reduced by (C). people that insulin may cause an rise in blood which performance (E). In such a it is to on extra carbohydrate than reduction for Table for on of preexercise is a for reduction of insulin when the is given within 1 h of the exercise, while the of reduction is for exercise h when regular insulin. (15) (B). For evening exercise, it may be to reduce the rapid analogue the evening meal by as well as g of carbohydrate the activity. insulin a reduction in insulin or basal in or in and/or extra following the activity is or activities such as a reduction of long-acting insulin the and on the of the activity or a reduction in the basal insulin the and the following the activity. High and may be more likely to because of (E). For of exercise it may be to prior to the start of the activity and remain for up to h during an In these patients may require a (i.e., of the basal insulin while if to reduce any a of the basal insulin effect during the exercise, the to be at least 90 min the exercise but many that the should not be for more than 2 The may be to to a basal 90 min the activity the of exercise. if the is during exercise, hypoglycemia can for hours after the of the activity (C). a short of intense exercise VO2 responses to which for approximately 2 h in adults with type 1 diabetes (B). when pre-exercise plasma glucose was there a which for 2 h in patients (C). This may be exaggerated if the has been during exercise. The rise in blood glucose may be prevented by a of insulin at or after the exercise is (E). insulin to activity. the in insulin exercise. type and amount of carbohydrate for activities. of hypoglycemia and reduction in insulin. In of poor control or intense exercise is likely to be because of the effect of action of the counter-regulatory In one in patients with a blood glucose of and a further rise in blood glucose during 40 min of exercise (B). The rapid production of with impaired muscle glucose uptake will not only to but also may and it is important for families to be not in strenuous exercise if blood glucose is and or are in the or of in It is a that no insulin is when exercise is to be This be a insulin is by a long-acting and under provides to (E). This is for rapid and of levels and is when (E). of blood than is in children with diabetes and exercise is and should be if preexercise blood glucose levels are or with approximately or of daily all meal and basal in and exercise have (E). When insulin is not reduced to for exercise, it is usually necessary to extra carbohydrate in to This is dependent upon type and duration of activity. The amount of carbohydrate on the of the and the activity performed as well as the level of circulating insulin (15) (B). to g CHO/kg body of strenuous exercise may be carbohydrate for on duration of activity and body are found in a by Gary by and and for in a by and (16). It is adolescents and young adults the effect of upon the ability to to exercise and blood glucose. the glucose in subjects with diabetes by gluconeogenesis not and hypoglycemia more likely and is when in exercise, especially as may also While not to people with diabetes, the of should be in be upon glucose a in body because of may performance (C). In both can often be by drinks, but if is a risk, fluids should also be should and such that there is no in body weight preexercise may to be as as in adolescents exercising in and (B). up to g CHO/kg body of strenuous or longer-duration exercise when circulating insulin levels are so hypoglycemia is more is a fluids also are glucose is for the with diabetes so that in glycemic responses can be should of blood the duration and intensity of exercise as well as the to glucose in the normal of glucose should be and after the of exercise with to the of in hours after exercise and is on strenuous activities as hypoglycemia is It remains levels hypoglycemia, and are after exercise. In one a blood glucose of for hypoglycemia while found no for hypoglycemia after exercise in the It remains to be seen the impact of continuous glucose will should be when in (B). glucose may more at In circumstances control is to the e.g., on a long further with the only between In such as a and of to the body will usually should be at the of hypoglycemia may be with of of of activity, and glucose results is important for diabetes control during exercise. of hypoglycemia is high, and should be if blood glucose should be that the and chosen are for the will be While this chapter is at the of intense and/or physical activity, it is that the can be for more exercise. In the normal most young people will have at least one of physical and with hypoglycemia will be dependent upon all of the For all that will be is a of g for a or a or or sports This may also be a to allow a such as or that will cause the sugar to be more This can it more for activity, for or long However, the extra will not a with weight Where a or a is a reduction in the preexercise or a basal may be (Table For a short of may be to allow activity. For longer periods of physical activity a reduction in basal insulin by should be considered with carbohydrate are a part of the and many young people with diabetes also have the to diabetes mainly in the with the usually and by diabetes professionals with of insulin and food professionals can more the day-to-day of diabetes by in diabetes and in some this is a training The benefits of a in the are but is often and the activity is with with diabetes, there are real opportunities to of for children with diabetes that on and insulin for exercise can result in improved glycemic control and may have to be reduced to hypoglycemia, especially in children not to physical activity, and it is to with a reduction in (C). When for a on a or an for insulin sensitivity will increase after which will for insulin by or even especially if not to physical The increased insulin sensitivity will for at least a of after Where young people will be for by professionals it is that both the adults and the are with and as well as should be of the to plan activities often last longer than so extra and hypoglycemia should be While very it may be for a diabetes team to to a that a young person should not go on a activity For be if the person with diabetes such as of insulin or of The a and the impact upon the in the the for children with diabetes. and hypoglycemia should be at on and of exercise, and is should be for should to for children with diabetes. possible should be to a young person with diabetes has or to understand to control while However, diabetes have a of and there are when is participation is and It be to provide such of the overall control and of the as well as the possible impact of any other health such as diabetes It may be possible to a little to the young person that it is in to with the team to in almost any sport or exercise is likely to be in but for the person with diabetes, this is even more very one should diabetes and to and in a sports team should be of a person with diabetes and to the hypoglycemia It is to have on the body in the of a or of diabetes in other may be e.g., the and of and be with It is to that the is making some and to blood glucose or to or may to an increased of in a person with diabetes (C). have allowed individuals with diabetes to under controlled circumstances while in and only people with diabetes are allowed to The limit in the is if part in a training A of performed by individuals with diabetes has been no of or hypoglycemia even in to adolescents In were in very with no of hypoglycemia should be during because this the response during exercise or hypoglycemia (B). As to the situation in type 1 diabetes, there is no that exercise has a and important part in the of type 2 diabetes. results in in body the amount of and the amount of and This increases the and blood and and increases the of cardiovascular and The of studies on type 2 diabetes and exercise have been in but there is to that the results are applicable to adolescents as well (E). and other of adolescents in type 2 diabetes has been have characterized by physical activity A training increased insulin sensitivity in adolescents of in body in adults with impaired glucose tolerance that exercise can reduce the of type 2 diabetes In a it was found that exercise training reduced by an amount that should the of diabetic This effect was not by weight The of hypoglycemia in type 2 diabetes is than in type 1 because counter-regulatory are but patients insulin or long-acting may require reduction in sports are for with type 1 diabetes is in control and (E). However, patients have or should exercise conditions that can result in blood such as any in which a is or high-intensity (E). blood during exercise can be in patients with with should be to and and should and other sports that of and Diabetes for more on diabetes and exercise (Table This is a chapter in the of the for and Diabetes The of these will be as a or should be to the The in the is the same as that by the Diabetes the of the in Diabetes Type 1 Diabetes in and Young of A The and in and Diabetes and The to Diabetes and Diabetes