Exercise, Blood Glucose, and Insulin



††††††††††† Insulin dependent diabetes mellitus, also known as type 1 diabetes, causes severe neurological and cardiovascular disorders.Insulin plays a crucial role in maintaining glucose levels within the circulatory system.Glucose levels that are unregulated in the DM 1 patient may lead to possible life threatening situations.These situations can be either acute, such as diabetic (hyperglycemic) coma; or chronic, such as distal neuropathy and atherosclerosis.The proper education of exercise, nutrition, and monitoring of blood glucose levels is crucial.Physical therapists should necessitate this education for our patients that their acts are imperative to a healthy life.


Diabetes is a condition that can be managed to an extent.Management will reduce the health care costs and promote longevity to our patientís lives.The role of our profession in patient education is important.Exercise and nutrition has shown to reduce the amounts of insulin required for our bodies.1As physical therapists, we must promote the benefits of exercise and nutrition to diabetes patients.


The relationship between exercise, blood glucose, and insulin will be broken down into the following categories: exercise and itís effects on blood glucose, exercise and itís effects on insulin, and insulin and itís effects on blood glucose.These categories will demonstrate the effects of pharmacologic interventions and non-pharmacologic interventions on diabetes.The best possible solution for control of blood glucose levels will be explored.This will demonstrate the importance of insulin injections vs. nutrition/exercise and their effects on blood glucose levels.The final section of this mini-paper will discuss the appropriate regime to be used for a patient with Insulin Dependent Diabetes Mellitus (IDDM).


Exercise and itís Effects on Blood Glucose


Exercise demonstrates positive effects on both the cardiovascular and pulmonary systems.These systems are directly affected by IDDM.By utilizing exercise as a treatment, the therapist can decrease the effects of diabetes.A brief overview of the effects of IDDM on the cardiovascular and neurological systems is reviewed below.This is followed by exercise and itís effects on glucose.


IDDM has various effects on the bodyís systems.In the cardiovascular system, IDDM causes a decreasing diameter inside our arteries, which is secondary to the increased deposits ofďfatty plaques.Ē2 This decrease in arterial diameter causes an increased cardiac output in order to maintain oxygenation of the bodyís tissues. When cardiac output is increased, the respiration rate is also increased to adequately oxygenate the blood.The pulmonary system is then stressed to match the cardiac output.


This cycle is caused primarily by the increased blood-glucose levels found in IDDM patients.An increase of glucose in the bodyís vascular system, and the inability to absorb it, leads to increased amounts of sorbitol to be deposited around nerve cells.2IDDM patientís with diabetic neuropathy are at a higher risk to injure their distal extremities.With decreased sensation from diabetic neuropathy, IDDM patients are at higher risk of developing integumentary injuries.


The cycle becomes worse with the possible effects on the distal vascular system.With decreased arterial size, secondary to fatty deposits, the bodyís capillary system also begins to restrict blood flow.IDDM then takes a major effect on the healing process.Wound care is challenged secondary to decreased capillary sufficiency.Minor scrapes or injuries to the distal extremities can require months of wound care and rehabilitation.The immune system is challenged by decreased phagocytosis of leukocytes.2This challenges the body in itís ability to eradicate infections.


The main goal of exercise in a patient with IDDM is to begin the management of blood glucose levels.Blood glucose levels are decreased during periods of exercise.2†† Glucose is lowered by exercise due to increased permeability to glucose in peripheral tissues.1 Glucose levels are the primary cause of cardiovascular and neurological disorders in diabetics.With proper exercise, IDDM patients can begin to manage the amounts of insulin required.Exercise should primarily be aerobic.Resistance exercises tend to increase blood pressure.Blood pressure increase is caused by increased intra-thoracic pressure and muscular compression on blood vessels.This is non-beneficial to long-term diabetic patients who may have decreased blood flow from atherosclerosis.This could result in possible cerebral vascular accidents or heart attacks.


Aerobic exercise offers complete muscle group workouts.This exercising also increases blood flow through distal muscle groups increasing oxygenation to tissues in the feet and hands.Distal extremity blood flow is decreased primarily in a stocking and glove pattern.This increase in oxygenation lessens the chances of tissue ischemia and neuropathy and increases capillary blood flow.Aerobic exercise also increases stroke volume and heart muscle contractibility thus increasing vascular efficiency.


Exercise and itís Effects on Insulin


Exercise also plays an important role in regulating insulin within the body.With exercise, insulin is not readily released from the pancreas due to the lowered blood glucose levels.This self-regulation allows the body to not require insulin injections.Unfortunately, exercise is easier said than done.Proper education to IDDM patients will demonstrate that with healthy lifestyle choices, diabetes can me managed.The possibility may occur that exercise and nutrition can become the patientís medication.


The body is more sensitive to insulin during exercise.With the decreased blood glucose levels, hypoglycemia may occur.This condition can cause severe neurological damage.Decreased oxygenation to the brain can cause death.2†† IDDM patients must regulate their blood glucose levels at the beginning, middle, and end of their exercise routines.Glucose levels below 70mg/dl will place a patient in a hypoglycemic state.Un-educated patients may attempt insulin injections and exercise in the same period that can lead to the above-mentioned conditions.


Insulin and itís Effects on Blood Glucose


††††††††††† Insulin has many effects on the blood glucose levels throughout our body.With increased levels of glucose in the blood, insulin is secreted from the pancreas.Insulin is then released from the beta cells that are a type of islet cells.3 This release of insulin causes an increased uptake of glucose in muscles, red blood cells, and fat cells.3 The increased uptake manages the glucose levels in the body.If the glucose levels are steadily rising, a state called, hyperglycemia may occur.Hyperglycemia (glucose levels > 140 mg/dl) occurs with the increased levels of glucose in the bloodstream.2


Exercise plays a crucial role when dealing with glucose levels.While moderate exercise does decrease glucose levels in the body, rigorous exercise can cause epinephrine to be released.2This release of epinephrine can cause glucose levels to elevate by transporting, ďstored glucose to blood glucose.Ē2The release of epinephrine can put an IDDM patient at risk to go from a controlled glucose level to a condition called diabetic ketoacidosis.This condition can cause a diabetic coma if not managed correctly.IDDM patients must be educated on the importance of various levels of exercise, and the effects on glucose levels.†††


Another primary role of insulin is the processing of various nutritional elements such as proteins and carbohydrates.Insulin is involved in amino acid transport.Insulin is disrupted in IDDM patients, and does not aide in protein synthesis.2Without the correct processing of these elements, our bodies begin to metabolize fats.The fats, after being broken down, increase the amount of glucose in our body.The increases in both glucose and ketones may lead to diabetic ketoacidosis.Insulin affects not only the absorption of glucose, but also the synthesis of various molecules.This leads to increased glucose production.This cycle is what IDDM patients need to comprehend in order to see the benefits of exercise.


IDDM patients must understand why insulin injections need to occur at specific times.Injecting insulin before exercise can cause glucose levels to diminish, leading to hypoglycemia.Insulin must not be injected within one hour of performing exercise in any extremity.2This is because insulin uptake is increased at the injection site.This will cause a hypoglycemic affect to occur leading to potential injury.Insulin can be regulated during pre and post exercise with proper nutrition and blood glucose monitoring.This monitoring will keep a patient on top of their condition and able to properly manage IDDM.


Guidelines for Diabetic Patients who Exercise


The most crucial guideline for IDDM patients who exercise is the monitoring of blood glucose levels.Before any exercise programs, a complete medical evaluation should be performed to obtain baseline measurements.IDDM patients must monitor their blood glucose levels when performing exercises.Monitoring of the glucose levels should occur before, during, and after exercises.This monitoring allows for the prevention of hypo and hyperglycemic conditions.The following guidelines will be listed in outline form with a rationale subset below:


1.      Footwear & clothing:

a.       Footwear should be donned during exercises that allows comfortable and breath-ability to the patientís feet.The importance of proper footwear is to protect patients from incurring any injuries during exercise.With decreased sensation from neuropathy, the feet must maintain injury free from bruising and blisters.If not, injuries will take longer to heal, thus causing the patient an extended period away from their exercise program.

b.      Clothing needs to allow breath-ability and be appropriate for the exercising environment.Clothing that retains heat and moisture is not appropriate for patients during exercising.An increase in core temperature will decrease fluid retention and lead to a quicker onset of dehydration.†††

2.      Hydration:

a.       Proper hydration should be within an armís reach so that patient can have easy access to liquids.Hydration should not be with sodas or sugary beverages, which will alter the blood/glucose levels.Hydration with water should occur before the onset of thirst.†††

3.      Sugar snack:

a.       A sugary snack can be given before exercise if blood glucose levels are to low.2†† The importance of the snack is to increase blood glucose levels in cases where glucose levels are lower than 100 mg/dl.2†† These snacks should also be readily available and not in vending machines.The effects of hypoglycemia are decreased with the intake of a sugary snack.A carbohydrate snack should be eaten for every 30 minute session of exercise for IDDM patients.2

4.      Aerobic exercise versus resistance:

a.       Aerobic exercise is the best form of exercise for Type I or II diabetic patients.This exercise does not require quick bursts of energy, and resistance can be measured for appropriateness.Aerobic exercise also allows the ability to increase cardiac muscle strength.This improves the cardio and pulmonary systems efficiency.

b.      Resistance exercise may be performed by IDDM patients.The guidelines are to closely monitor blood pressure, heart rate, and respiratory rate.The importance of this monitoring is to protect long-term IDDM patients from increasing blood pressure to an un-healthy measure.Resistance exercises increase blood pressure greatly.Restricted blood flow in IDDM patientís arteries can cause possible CVAís or heart attacks.Resistance exercises are more appropriate for diabetic patients who are young.This is due to the decreased length of time the disease has had on affecting their vascular system.


Exercise Program


  1. Warm up
    1. Warm up includes stretching with a slow increase in heart rate
    2. Blood glucose measurement
  2. Exercise period
    1. Aerobic exercise should include at least 20 minutes of exercise

                                                               i.      Examples

1.      Bike

2.      Tread mill

3.      Swimming

    1. Blood glucose measurement 10 minutes into program
    2. Hydrate continuously through session
    3. Carbohydrate snack if over 30 minutes of exercise.
  1. Cool Down
    1. Slow decrease in heart rate with stretching.
    2. Blood glucose measurement

                                                               i.      Lowered glucose levels would be a reason to have a small meal to increase blood glucose (Likely)

                                                             ii.      Raised glucose levels will require an insulin injection to decrease glucose in the bloodstream (Not as Likely)

    1. Hydrate




  1. Charles D. Ciccone.Pharmacology in Rehabilitation.Pennsylvania: F.A. Davis; 2002.
  2. C.C. Goodman and T.E. Snyder. Differential Diagnosis in Physical Therapy.Pennsylvania: W. B. Saunders Company; 1995.
  3. Normal Regulations of Blood Glucose Levels.Endocrine Web.1998.Available at www.endocrineweb.com.Accessed July 28, 2002.