National athletic trainers' association position statement: management of the athlete with type 1 diabetes mellitus.

Abstract

To present recommendations for the certified athletic trainer in the management of type 1 diabetes in the athlete.
In managing diabetes, the most important goal is to keep blood glucose levels at or as close to normal levels as possible without causing hypoglycemia. This goal requires the maintenance of a delicate balance among hypoglycemia, euglycemia, and hyperglycemia, which is often more challenging in the athlete due to the demands of physical activity and competition. However, effectively managing blood glucose, lipid, and blood pressure levels is necessary to ensuring the long-term health and well-being of the athlete with diabetes.
These recommendations are intended to provide the certified athletic trainer participating in the management of an athlete with type 1 diabetes mellitus with the specific knowledge and problem-solving skills needed. Athletic trainers have more contact with the athlete with diabetes than most members of the diabetes management team do and so must be prepared to assist the athlete as required.

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Volume 42•Number 4•December 2007
Journal of Athletic Training
? by the National Athletic Trainers’ Association, Inc
www.journalofathletictraining.org
2007;42(4):536–545
National Athletic Trainers’ Association Position
Statement: Management of the Athlete With
Type 1 Diabetes Mellitus
Carolyn C. Jimenez, PhD, ATC*; Matthew H. Corcoran, MD, CDE†;
James T. Crawley, MEd, PT, ATC‡; W. Guyton Hornsby, Jr, PhD, CDE?;
Kimberly S. Peer, EdD, LATC¶; Rick D. Philbin, MBA, MEd, ATC#;
Michael C. Riddell, PhD**
*West Chester University, West Chester, PA; †Lehigh Valley Hospital, Allentown, PA; ‡Dominican College,
Orangeburg, NY; ?West Virginia University, Morgantown, WV; ¶Kent State University, Kent, OH; #Animas Corp,
West Chester, PA; **York University, Toronto, ON
Objective: To present recommendations for the certified
athletic trainer in the management of type 1 diabetes in the
athlete.
Background: In managing diabetes, the most important
goal is to keep blood glucose levels at or as close to normal
levels as possible without causing hypoglycemia. This goal
requires the maintenance of a delicate balance among hypo-
glycemia, euglycemia, and hyperglycemia, which is often more
challenging in the athlete due to the demands of physical ac-
tivity and competition. However, effectively managing blood
glucose, lipid, and blood pressure levels is necessary to en-
E
goal of diabetes management is to consistently maintain blood
glucose levels in a normal or near-normal range without pro-
voking undue hypoglycemia.1–5Although several exercise
guidelines for persons with diabetes have been published
(American Diabetes Association’s ‘‘Physical Activity/Exercise
and Type 2 Diabetes,’’6American College of Sports Medi-
cine’s ‘‘Exercise and Type 2 Diabetes,’’7and the joint state-
ment of the American College of Sports Medicine and the
American Diabetes Association, ‘‘Diabetes Mellitus and Ex-
ercise’’8), none address issues of concern for athletic trainers
(eg, blood glucose management strategies during injury or the
effect of therapeutic modalities on blood glucose control). The
following position statement and recommendations provide
relevant information on type 1 diabetes mellitus and specific
recommendations for athletic trainers who work with patients
with diabetes.
suring the long-term health and well-being of the athlete with
diabetes.
Recommendations: These recommendations are intend-
ed to provide the certified athletic trainer participating in the
management of an athlete with type 1 diabetes mellitus with
the specific knowledge and problem-solving skills needed.
Athletic trainers have more contact with the athlete with di-
abetes than most members of the diabetes management
team do and so must be prepared to assist the athlete as
required.
Key Words: hypoglycemia, hyperglycemia, insulin replace-
ment therapy
ffective management of glycemic, lipid, and blood pres-
sure control plays an important role in the health out-
comes of persons with diabetes mellitus. The primary
RECOMMENDATIONS
Based on current research and literature, the National Ath-
letic Trainers’ Association (NATA) suggests the following
guidelines for management of athletes with type 1 diabetes
mellitus. These recommendations have been organized into the
following categories: diabetes care plan; supplies for athletic
training kits; preparticipation physical examination (PPE); rec-
ognition, treatment, and prevention of hypoglycemia; recog-
nition, treatment, and prevention of hyperglycemia; insulin ad-
ministration; travel recommendations; and athletic injury and
glycemic control.
Diabetes Care Plan
1. Each athlete with diabetes should have a diabetes care
plan for practices and games. The plan should include the
following:
a. Blood glucose monitoring guidelines. Address frequen-
cy of monitoring and pre-exercise exclusion values.
b. Insulin therapy guidelines. Should include the type of
insulin used, dosages and adjustment strategies for
planned activities types, as well as insulin correction
dosages for high blood glucose levels.
c. List of other medications. Include those used to assist
with glycemic control and/or to treat other diabetes-
related conditions.
d. Guidelines for hypoglycemia recognition and treat-
ment. Include prevention, signs, symptoms, and treat-
ment of hypoglycemia, including instructions on the
use of glucagon.
e. Guidelines for hyperglycemia recognition and treat-
ment. Include prevention, signs, symptoms, and treat-
ment of hyperglycemia and ketosis.

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Journal of Athletic Training
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f. Emergency contact information. Include parents’ and/
or other family member’s telephone numbers, physi-
cian’s telephone number, and consent for medical treat-
ment (for minors).
g. Athletes with diabetes should have a medic alert tag
with them at all times.
Supplies for Athletic Training Kits
2. Supplies to treat diabetes-related emergencies should be
available at all practices and games. The athlete (or ath-
lete’s parents/guardians, in the case of minors) provides
the following items:
a. A copy of the diabetes care plan.
b. Blood glucose monitoring equipment and supplies. The
athletic trainer should check the expiration dates of
supplies, such as blood glucose testing strips and in-
sulin, on a regular basis. Blood glucose testing strips
have a code number located on the outside of the test
strip vial. The code number on the blood glucose meter
and test strip vial must match.
c. Supplies to treat hypoglycemia, including sugary foods
(eg, glucose tablets, sugar packets) or sugary fluids (eg,
orange juice, non-diet soda) and a glucagon injection
kit.
d. Supplies for urine or blood ketone testing.
e. A ‘‘sharps’’ container to ensure proper disposal of sy-
ringes and lancets.
f. Spare batteries (for blood glucose meter and/or insulin
pump) and, if applicable, spare infusion sets and res-
ervoirs for insulin pumps.
Preparticipation Physical Examination
3. Athletes with type 1 diabetes should have a glycosylated
hemoglobin (HbA1c) assay every 3 to 4 months to assess
overall long-term glycemic control. However, the HbA1c
value is not used to make day-to-day decisions concerning
participation.
4. An annual examination for retinopathy, nephropathy, and
neuropathy is recommended along with an annual foot
examination to check sensory function and ankle reflexes.
Screening for cardiovascular disease should occur at in-
tervals recommended by the athlete’s endocrinologist or
cardiologist. Exercise limitations or restrictions for ath-
letes with diabetes-related complications should be deter-
mined by the athlete’s physician.9–11
Recognition, Treatment, and Prevention of
Hypoglycemia
5. Strategies to recognize, treat, and prevent hypoglycemia
typically include blood glucose monitoring, carbohydrate
supplementation, and/or insulin adjustments. Athletes with
diabetes should discuss with their physicians specific car-
bohydrate qualities and quantities as well as the use of an
insulin reduction plan for activity (Appendix 1).
6. Athletic trainers should know the signs, symptoms, and treat-
ment guidelines for mild and severe hypoglycemia. Hypo-
glycemia is defined as mild if the athlete is conscious and
able to swallow and follow directions or severe if the athlete
is unable to swallow, follow directions, or eat as directed or
is unconscious. Treatment of severe hypoglycemia requires
a glucagon injection, and athletic trainers should be trained
in mixing and administering glucagon. The athlete, athlete’s
family, or physician can provide appropriate training (Ap-
pendix 2).
Recognition, Treatment, and Prevention of
Hyperglycemia
7. Athletes with type 1 diabetes and athletic trainers are ad-
vised to follow the American Diabetes Association (ADA)
guidelines for avoiding exercise during periods of hyper-
glycemia (Appendix 3).
8. Athletes with type 1 diabetes who experience hypergly-
cemia during short-term, intense, and stressful periods of
exercise should consult with their physicians concerning
an increased basal rate or the use of small insulin boluses
to counteract this phenomenon.30
9. Athletes should drink noncarbohydrate fluids when blood
glucose levels exceed the renal glucose threshold (180 mg/
dL, or 10 mmol/L), which may lead to increased urination,
fluid loss, and dehydration.
Insulin Administration
10. Insulin should be administered into the subcutaneous tis-
sue. The abdomen, upper thigh, and upper arms are com-
mon sites for injection. Intramuscular injections of insulin
should always be avoided as muscle contractions may ac-
celerate insulin absorption.12
11. Depending on the type of insulin used by the athlete, heat
and cold should be avoided for 1 to 3 hours after an in-
jection of rapid-acting insulin (eg, lispro, aspart, or glu-
lisine) and up to 4 hours for fast-acting (eg, regular) in-
sulin.31,32Heat may increase insulin absorption rates.
Thus, athletes with type 1 diabetes should avoid warm
whirlpools, saunas, showers, hot tubs, and baths after in-
jection. Local heat-producing modalities such as moist hot
packs, diathermy, and thermal ultrasound should not be
applied directly over an infusion or injection site. By con-
trast, cold may decrease insulin absorption rates. There-
fore, athletes with type 1 diabetes should avoid using ice
and cold sprays directly over the injection or infusion site
after insulin administration. Similarly, cold whirlpools
should be avoided after insulin injection.
12. Insulin pump users should replace insulin infusion sets
every 2 to 3 days to reduce skin and infusion site irrita-
tion.
13. Extreme ambient temperature (?36?F or ?86?F [?2.2?C
or ?30?C]) can reduce insulin action. Athletes with type
1 diabetes are advised to check blood glucose levels fre-
quently and replace the entire insulin-filled cartridge and
infusion set if any signs of unusual hyperglycemia occur
in extreme environmental conditions.
Travel Recommendations
14. Athletic trainers should review the advice provided by the
Transportation Security Administration (TSA) in conjunc-
tion with the ADA for airline passengers with diabetes
traveling within the United States.33In addition, athletes
are advised to carry diabetes supplies with them and have
prescriptions available in the event that medication or sup-
plies need to be replaced. Due to extreme temperature

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Volume 42•Number 4•December 2007
fluctuations that could affect insulin action, insulin should
not be stored in the cargo hold of the airplane.
15. When traveling, athletes with type 1 diabetes are advised
to carry prepackaged meals and snacks in case food avail-
ability is interrupted. If travel occurs over several time
zones, insulin therapy may need to be adjusted to coor-
dinate with changes in eating and activity patterns.
Athletic Injury and Glycemic Control
16. Trauma, even in persons without diabetes, often causes a
hyperglycemic state. Hyperglycemia is known to impair
the wound healing process; thus, for athletes with type 1
diabetes, an individualized blood glucose management
protocol should be developed for use during injury recov-
ery, including frequency of blood glucose monitoring.
BACKGROUND
Diabetes mellitus is a chronic endocrine disorder character-
ized by hyperglycemia. Persons with diabetes are at risk for
macrovascular, microvascular, and neuropathic complications.
For those without diabetes, normal fasting blood glucose levels
are 60 to 100 mg/dL (3.3 to 5.5 mmol/L); normal postprandial
levels are less than 140 mg/dL (7.8 mmol/L) 2 hours after a
meal. Chronic hyperglycemia leads to long-term damage, dys-
function, and failure of various organs, especially the eyes,
kidneys, nerves, and heart.34The literature supports the im-
portance of a consistent, near-normal blood glucose level, as
well as blood pressure and lipid control, for preventing dia-
betes-related complications and improving quality of life.2–5
Currently, approximately 20.8 million persons are living
with diabetes in the United States.35It is estimated that ap-
proximately 90% have type 2 diabetes and approximately 10%
have type 1 diabetes.35Type 2 diabetes typically occurs in
adults 40 years of age and older; however, the incidence of
type 2 diabetes in children is increasing, especially among
American Indian, African American, and Hispanic/Latino pop-
ulations. Type 1 diabetes typically occurs in children and
young adults.35,36
Type 1 diabetes is the rarer form of the disease, but athletic
trainers working in middle schools, secondary schools, colleges,
and many professional settings are more likely to encounter ath-
letes with type 1 than type 2 diabetes. This position statement
focuses on recommendations for the athlete with type 1 diabetes,
although athletic trainers can also play a crucial role in the dia-
betes-management plan of a person with type 2 diabetes.
Type 1 diabetes is characterized by absolute insulin defi-
ciency. It is considered an autoimmune disorder resulting from
a combination of genetic and unknown environmental factors.
The signs and symptoms of type 1 diabetes develop rapidly
and are related to hyperglycemia. Symptoms include frequent
urination, thirst, hunger and polyphagia, weight loss, visual
disturbances, fatigue, and ketosis.37Usually, athletes are able
to resume exercise and sports within weeks of starting insulin
treatment as long as a treatment plan is developed and a sup-
port team exists. The treatment plan for persons with type 1
diabetes focuses on a self-care plan predicated on exogenous
insulin, monitoring of blood glucose, healthy nutrition, and
exercise.
DIABETES MANAGEMENT TEAM AND THE
DIABETES CARE PLAN
Proper management of blood glucose levels during practices
and games allows the athlete with diabetes to compete in a
safe and effective manner. Maintaining a near-normal blood
glucose level (100 to 180 mg/dL, or 5.5 mmol/L to 10 mmol/
L) reduces the risk of dehydration, lethargy, hypoglycemia,
and autonomic counterregulatory failure. This goal is best
achieved through a team approach. The team-management ap-
proach to providing support for patients with diabetes is well
established in the allied health literature.38–46In school-aged ath-
letes, the team should include the school nurse, coach, and school
administrators. In adult athletes, diabetes is best managed by a
team that includes several health professionals.39,41–43,47,48Cre-
ating this team requires a deliberate, well-designed plan, which
defines the role of each individual in the supervision and care
of the athlete with diabetes. All members of the team should
be trained and willing to assist an athlete who is experiencing
a diabetes-related emergency.
Critical roles for the athletic trainer include prevention, rec-
ognition, and immediate care of hypoglycemia and hypergly-
cemia (with and without ketoacidosis); exercise nutrition; hy-
dration counseling; and helping the athlete to recognize the
intensity of the exercise session in order to adjust glucose and
insulin levels accordingly.41,49–51The athletic trainer also fa-
cilitates communication among the other members of the di-
abetes management team.
Athletes with type 1 diabetes should have a diabetes care
plan for practices and games.40The plan should identify blood
glucose targets for practices and games, including exclusion
thresholds; strategies to prevent exercise-associated hypogly-
cemia, hyperglycemia, and ketosis; a list of medications used
for glycemic control or other diabetes-related conditions;
signs, symptoms, and treatment protocols for hypoglycemia,
hyperglycemia, and ketosis; and emergency contact informa-
tion. The athlete must have access to supplies for managing
glycemic emergencies at all times. When the athlete requires
assistance, the athletic trainer and/or other members of the
diabetes management team (eg, coach) must have immediate
access to these supplies. The athlete or parent/guardian should
provide the necessary supplies and equipment.
PREPARTICIPATION PHYSICAL EXAMINATION FOR
ATHLETES WITH TYPE 1 DIABETES
A thorough PPE should begin with the team or primary care
physician. This examination should include a sports history,
assessment of the level of diabetes self-care skills and knowl-
edge, general physical examination emphasizing screening of
diabetes-related complications, and discussion of how sports
participation will affect blood glucose and blood pressure con-
trol. As part of the PPE, the athlete’s endocrinologist or pri-
mary care physician should provide an assessment of the cur-
rent level of glycemic control, information concerning the
presence and status of diabetes-related complications, and
blood glucose management strategies. Completion of the PPE
may require consultation with other specialists (eg, cardiolo-
gist, ophthalmologist), especially in the case of diabetes-relat-
ed complications.52Athletic trainers are referred to the Hand-
book of Exercise in Diabetes,53published by the American
Diabetes Association, for further readings on prescreening of
the active individual with type 1 diabetes.

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Journal of Athletic Training
539
Preparticipation Physical Examination and Glycemic
Control
The athlete’s level of long-term glycemic control should be
listed on the PPE. Long-term glycemic control is assessed by
an HbA1c test every 3 to 4 months.54Normal HbA1c levels,
depending on the laboratory assay, are generally between 4.0%
and 6.0%. The ADA recommends a target HbA1c level of 7%
or less for adults on intensive insulin therapy and 7.5% or less
for teens and adolescents.55An HbA1c level of 7% correlates
with an average blood glucose level of approximately 150 mg/
dL (8.3 mmol/L). Other organizations, such as the American
Association of Clinical Endocrinologists, set more stringent
recommendations, such as 6.5% (approximately 135 mg/dL
[7.5 mmol/L]) or less in adults.56In general, a lower HbA1c
level correlates with a lower risk of diabetes-related compli-
cations at the expense of an increased risk of hypoglycemia.2
The athletic trainer should understand that although the HbA1c
level provides a long-term perspective of glycemic control, it
is not used to make day-to-day participation decisions.
Preparticipation Physical Examination and
Screening for Diabetes-Related Complications
Athletic trainers should be aware that an athlete with type
1 diabetes may be chronologically young but may have had
the disease for many years and, as such, may experience di-
abetes-related complications. Common diabetes-related com-
plications are retinopathy, nephropathy, neuropathy, and car-
diovascular disease.
The ADA recommends an initial dilated and comprehensive
ophthalmologic examination 3 to 5 years after the diagnosis
of type 1 diabetes and an annual screening thereafter for ret-
inopathy, glaucoma, and cataracts.11,57Decisions regarding ac-
tivity limitations for the athlete are based on the presence and
degree of retinopathy and are made by the athlete’s physician.
Diabetic nephropathy is characterized by increased urinary
protein excretion. An initial examination is recommended 5
years after the diagnosis of type 1 diabetes and annually there-
after.9,58The athlete’s physician may limit exercise based upon
the presence and degree of nephropathy.
Peripheral neuropathy is characterized by bilateral sensory
involvement with dull perception of vibration, pain, and tem-
perature, particularly in the lower extremities. This is of par-
ticular concern for the athlete performing weight-bearing ac-
tivities. Athletic trainers should instruct the athlete with
diabetes to inspect the feet on a daily basis for any reddened
areas, blisters, abrasions, or lacerations. Cutting toenails
straight across, not walking barefoot, and avoiding poor-fitting
or tight shoes are all recommendations the athletic trainer
should provide.53Initial screening for peripheral neuropathy
is recommended 5 years after diagnosis.10Thereafter, an an-
nual examination for peripheral neuropathy (ie, examining
sensory function of the feet and checking the ankle reflexes)
is recommended.10The athlete’s physician may limit certain
physical activities in the presence of peripheral neuropathy.
Autonomic neuropathy may affect the cardiovascular, gas-
trointestinal, and neuroendocrine systems. This may predis-
pose the athlete with diabetes to exercise intolerance, ortho-
static hypotension, and hypoglycemic unawareness (a failure
to effectively recognize the signs and symptoms of low blood
sugar). The ADA recommends an initial screening for auto-
nomic neuropathy 5 years after the diagnosis of type 1 diabetes
and annually thereafter.10Suspected autonomic neuropathy
should be evaluated by the athlete’s endocrinologist and/or car-
diologist for exercise recommendations.59
Cardiovascular complications include myocardial infarction,
stroke, and peripheral arterial disease. The ADA recommends
that persons who have had type 1 diabetes for more than 15
years or have any other risk factor for coronary artery disease,
microvascular disease, peripheral vascular disease, or auto-
nomic neuropathy undergo a graded exercise stress test to
evaluate cardiovascular function.59For those athletes with, or
suspected of having, cardiovascular disease, referral to an en-
docrinologist and/or cardiologist for further assessment and
treatment is warranted.
INSULIN REPLACEMENT THERAPY
The objective of insulin replacement therapy is the near-nor-
malization of blood glucose levels while minimizing the risks of
hypoglycemia and weight gain. The standard of care is ‘‘intensive
insulin therapy.’’2Intensive insulin therapy uses basal and bolus
insulin doses to regulate blood glucose levels during fasting,feed-
ing, and hyperglycemic periods. Basal insulin is used to maintain
glycemic stability during fasting periods and delivers a steady,
low dose of insulin 24 hours a day. Bolus insulin is used to
control elevations in blood glucose levels that occur after eating
or to lower blood glucose levels during hyperglycemia. Bolus
insulin doses are determined by several factors, including the
prevailing blood glucose level, carbohydrate content of the meal,
and anticipated exercise.
Insulin pumps and multiple daily injections (MDI) are the
primary methods used to deliver basal and bolus therapy. In-
sulin pump therapy uses novel technology to deliver rapid-
acting or fast-acting insulin to provide both basal and bolus
doses (see Appendix 4 for examples of fast-acting and rapid-
acting insulins). However, rapid-acting insulins are considered
the standard of care in insulin pump therapy because of their
physiologic profile. In insulin pump therapy, basal insulin is
continuously administered via preset basal infusion rates (ie,
1.2 units of insulin per hour) over a 24-hour period. At meals
or to correct hyperglycemia, the athlete uses a bolus-dosing
menu on the insulin pump to dispense insulin dosages (ie, 5
units of insulin).
The MDI plans require patients with diabetes to inject both
basal and bolus insulins. Typically, basal insulin is injected 1 or
2 times a day. Unlike insulin pump basal infusion rates, basal
therapy with MDI consists of injecting a fixed amount of long-
acting insulin, such as 6.5 units. Optimal basal insulin use with
MDI has a long biological activity (18 to 24 hours) and a rela-
tively peakless profile. Patients with diabetes may use 2 to 4
injections of rapid-acting or fast-acting insulin to provide bolus
coverage at mealtimes or to correct hyperglycemia. Bolus dosing
with MDI is similar to that with insulin pump therapy in that a
fixed amount of insulin (ie, 5 units of insulin) is administered
based upon the current blood glucose level, carbohydrate content
of the meal, and any anticipated exercise.
The choice to use an insulin pump or MDI is made by the
athlete in consultation with the physician. Each method of de-
livery has distinct advantages and disadvantages. Advantages
of insulin pump therapy include the use of a single rapid-
acting insulin to achieve a more physiologic insulin profile;
the ability to alter the basal rate before or during exercise; the
ability to suspend or disconnect the pump; ‘‘smart pumps’’ that
use internal calculators to determine an estimated amount of
insulin in circulation, which may help to prevent excessive

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Volume 42•Number 4•December 2007
insulin dosing; allowance for flexible meal schedules; and
avoiding the regular use of needles for insulin administration.
Disadvantages of insulin pump therapy include possible dam-
age during contact sports; risk of hyperglycemia and ketosis
if the insulin pump malfunctions or is inadvertently discon-
nected from the athlete; infusion set displacement, as heavy
sweating or water contact may reduce the ability of adhesives
to hold the infusion set in place; movement or contact leading
to irritation at the infusion site, especially in those using metal
needle infusion sets; and extreme ambient temperatures
(?36?F [2.22?C] or ?86?F [30?C]), which can affect insulin
housed within the pump and interfere with insulin action.65
The advantages of MDI include a lower cost of operation
compared with insulin pumps and the absence of a connection
to a device. Disadvantages include the inability to manipulate
basal insulin levels during exercise, the need for regular in-
jections, and the lack of flexibility regarding meal timing and
unplanned exercise.
Insulin absorption is the rate-limiting step in insulin activity
for both the insulin pump and MDI, and many factors may
affect the absorption rate.66Athletes should use consistent sites
for injections to eliminate absorption differences among body
regions (ie, abdomen versus triceps). Appendix 5 lists some
of the variables that can affect absorption rates.
The athlete and diabetes management team should be aware
of insulin-specific pharmacokinetic and pharmacodynamic
properties. For example, rapid-acting insulin analogs (lispro,
aspart, glulisine) all reach peak circulating levels within 90
minutes of administration. This peak represents the maximal
glucose-lowering effect and greatest risk for hypoglycemia.
See Appendix 4 for pharmacokinetic properties of commonly
used basal and bolus insulins.
HYPOGLYCEMIA
Hypoglycemia is the most severe acute complication of inten-
sive insulin therapy in diabetes, and exercise is its most frequent
cause.1,68Intensive insulin therapy is associated with a 2-fold to
3-fold increase in severe hypoglycemia (ie, the person with dia-
betes requires assistance).2The risk of severe hypoglycemia is
higher in males, adolescents, and those who have already had a
severe episode.2Although responses are individualized, signs and
symptoms of hypoglycemia typically occur when blood glucose
levels fall below 70 mg/dL (3.9 mmol/L).
Under most circumstances, hypoglycemia is the result of
overinsulinization, both during and after exercise. Several fac-
tors contribute to overinsulinization. First, the rate at which
subcutaneously injected insulin is absorbed increases with ex-
ercise due to increases in body temperature and in subcuta-
neous and skeletal muscle blood flow.69Second, exogenously
administered insulin levels do not decrease during exercise in
persons with type 1 diabetes. This is in contrast to exercise in
persons without diabetes, in whom insulin levels decrease dur-
ing exercise to prevent hypoglycemia. The inability to de-
crease plasma insulin levels during exercise in type 1 diabetes
causes relative hyperinsulinemia, which impairs hepatic glu-
cose production and initiates hypoglycemia, usually within 20
to 60 minutes after the onset of exercise.13,14,70Third, hypo-
glycemia during exercise can result from impaired release of
glucose-counterregulatory hormones (ie, glucagon and cate-
cholamines) caused by either a previous bout of exercise or
hypoglycemic episode.68As a result, athletes with type 1 di-
abetes who experience hypoglycemia on the days preceding
competition may be at risk for exercise-associated hypogly-
cemia.68Finally, exercise improves insulin sensitivity in skel-
etal muscle. Exercise-associated improvements in insulin sen-
sitivity may last for several hours to days after exercise. Thus,
some athletes experience a phenomenon known as postexer-
cise late-onset hypoglycemia, which may occur while the ath-
lete is sleeping. Athletes who experience nighttime hypogly-
cemia require additional blood glucose monitoring in addition
to a snack.15,71
Managing blood glucose levels during practices and games
and preventing hypoglycemia are challenges. Typically, hy-
poglycemia prevention uses a 3-pronged approach of blood
glucose monitoring, carbohydrate supplementation, and insulin
adjustments. Appendix 1 lists strategies to prevent hypogly-
cemia during and after practices and games. The athlete and
the diabetes management team should work together to deter-
mine which strategies to employ.
Hypoglycemia normally produces noticeable autonomic or
neurogenic symptoms. Autonomic symptoms include tachy-
cardia, sweating, palpitations, hunger, nervousness, headache,
trembling, and dizziness. These symptoms typically occur at
blood glucose levels ?70 mg/dL (?3.9 mmol/L) in persons
with diabetes and are related to the release of epinephrine and
acetylcholine.26,27As glucose continues to fall, symptoms of
brain neuronal glucose deprivation (neurogenic symptoms) oc-
cur and may cause blurred vision, fatigue, difficulty thinking,
loss of motor control, aggressive behavior, seizures, convul-
sions, and loss of consciousness; if hypoglycemia is prolonged
and severe, brain damage and even death can result. Symptoms
of hypoglycemia can be unique to a person with diabetes.72
Thus, the athletic training staff should be familiar with athlete-
specific symptoms of hypoglycemia and be prepared to act
appropriately. Hypoglycemia can cause some athletes to be
especially aggressive and unwilling to cooperate with instruc-
tions. Treatment guidelines for mild and severe cases of hy-
poglycemia are presented in Appendix 2.
ACUTE HYPERGLYCEMIA AND KETOSIS
Hyperglycemia with or without ketosis can occur during
exercise in athletes with type 1 diabetes. Hyperglycemia dur-
ing exercise is related to several factors. First, exercise (es-
pecially high-intensity exercise at 70% VO2max or ?85% of
maximal heart rate) can cause additional increases in blood
glucose concentrations and possible ketoacidosis in athletes
with poor glycemic control and those who are underinsulin-
ized. Without adequate insulin levels, blood glucose levels
continue to rise due to exaggerated hepatic glucose production
and impairments in exercise-induced glucose utilization.73
Second, even in well-controlled athletes with type 1 diabetes,
high-intensity exercise may result in hyperglycemia. High-in-
tensity exercise may lead to significant increases in catechol-
amines, free fatty acids, and ketone bodies, all of which impair
muscle glucose utilization and increase blood glucose levels.74
This exercise-associated rise in glucose levels is usually tran-
sient in the well-controlled diabetic athlete, declining as coun-
terregulatory hormone levels decrease, typically within 30 to
60 minutes.15Third, the psychological stress of competition is
frequently associated with increases in blood glucose levels
before competition. Although data do not exist for those with
type 1 diabetes, it is likely that excessive increases in coun-
terregulatory hormones occur before exercise, when anticipa-
tory stress is high.75Athletes may find that blood glucose