Type I Diabetes

Kris Hinnerichs

Diabetes Mellitus A condition where the body is no

longer able to control the glucose levels in the blood stream

~16 mill. cases in the United States 5-10% of those cases are type I Half of these cases are under age

20

Physiology Endocrine is Greek

Endo = within Krino = to separate

Intercellular chemical signals are produced within and secreted from endocrine glands, but have an effect away from the gland

Only effects target cells

Negative FeedbackHomeostasis of blood glucose levels

Blood glucose levels increase after a meal Insulin is secreted

Insulin causes tissues to take up glucose blood glucose levels decline

Rate of insulin secretion declines too rate of blood glucose uptake decreases

Endocrine Part of Pancreas Pancreatic islets (islets of

Langerhans) dispersed among exocrine portion

Beta cells secrete insulin Alpha cells secrete glucagon

Both work to regulate blood nutrient levels

Low Blood Glucose Levels Nervous system malfunctions Fats and proteins are broken down

causing ketoacidosis pH drops Ketones enter the blood stream

Amino acids are broken down and used to synthesize glucose by the liver

High Blood Glucose Levels Kidneys produce large volumes of

urine Urine is high in glucose molecules Frequent urination can lead to

dehydration

Insulin Secretion Increase

Elevated blood glucose levels

Parasympathetic stimulation / digestion

Blood levels of certain amino acids

Decrease Decreased

blood glucose levels

Sympathetic stimulation / exercise

Target Cells / Tissues Liver Adipose tissues Muscles Satiety center of hypothalamus

Glucose is converted to glycogen or fat, and the amino acids are used to synthesize protein

Glucagon Released from alpha cells when blood

glucose levels are low Bind to membrane-bound receptors in

the liver to cause the conversion of glycogen stored in the liver to glucose

Glucose is then released into the blood to increase blood glucose levels

Effects of Insulin and Glucagon on Target Tissues

Target Tissues Insulin Responses Glucagon Responses

Skeletal muscle, cardiac muscle, cartilage, bone fibroblasts, blood cells and mammary glands

Increases glucose uptake and glycogen synthesis; increases uptake of amino acids

Has little effect

Liver Increases glycogen synthesis; increases use of glucose for energy

Causes rapid increase in the breakdown of glycogen to glucose and release of glucose into the blood; increases the formation of glucose from amino acids and, to some degree, from fats; increases metabolism of fatty acids

Adipose cells Increases glucose uptake, glycogen synthesis, fat synthesis

High concentrations cause breakdown of fats; probably unimportant under conditions

Nervous system Has little effect except to increase glucose uptake in the satiety center

Has no effect

Blood Glucose-Raising Hormones During Exercise

Hormone Source Main Actions During Exercise

Epinephrine Adrenal Medulla Stimulation of muscle, and to a lesser extend, liver, glycogen breakdown, and mobilization of free fatty acids from adipose tissues; more is released with increasing exercise intensity

Norepinephrine Adrenal Medulla, Sympathetic Nerve Endings

Stimulation of liver to produce new glucose from available precursors; “feedforward” control of glucose along with epinephrine

Glucagon Pancreas Stimulation of liver glycogen breakdown and new glucose production from precursors to increase glucose output; changes in the insulin to glucagons ration largely affect glycemia

Growth Hormone Anterior Pituitary Direct stimulation of fat metabolism (release of free fatty acids from adipose) and indirect suppression of glucose use; stimulation of amino acid storage

Cortisol Adrenal Cortex Mobilization of amino acids and glycerol as precursors for hepatic glucose production and release of free fatty acids for muscle use

Pathophysiology Diabetes mellitus is characterized by

glucose concentrations in the blood that are high enough to overwhelm the reabsorption capabilities of the kidneys

Glycosuria—glucose in urine Polyuria—excessive urine production Other metabolic products are

present in abnormal concentrations

Causes Researchers are uncertain of causes Possibilities:

Genetic abnormalities Pathological conditions Injuries Immune disorders Hormonal imbalances Secretion of too little insulin Insufficient numbers of insulin receptors Defective receptors

Without Insulin… Cells cannot absorb glucose After meals, blood concentrations

become so elevated that the kidneys cannot reclaim all the glucose

High urinary concentrations of glucose limit ability to conserve water

High urinary concentrations of glucose cause frequent urination and possible dehydration

Without insulin… Chronic dehydration can cause

neural function and muscle weakness

Satiety center of brain responds with an exaggerated appetite

Endocrine tissues respond with more glucose

Ketoacidosis results

Long Term Therapy Dietary control and insulin Complications:

Tissue glucose demands cycle Meals Physical activity Emotional state Stress Other unpredictable factors

Diabetic Coma Cause—loss of NA+, K+, and ketone

bodies through excessive urination S/S—labored breathing, gasping for

air, fruity –smelling breath, nausea, vomiting, thirst, flushed skin, confusion, unconsciousness

Care—early detection of ketoacidosis, injection of insulin

Insulin Shock Cause—too much insulin in the body

results in hypoglycemia S/S—tingling sensations, physical

weakness, headaches, abdominal pain, rapid HR, tremors, drowsiness

Care—adhere to a carefully planned diet with a snack before activity, keep a sugar source available

Pharmacology Insulin is the main drug Insulin is a protein hormone and

must be injected

Refer to charts in handout

Exercise and Type I Diabetes Controversial Does not improve glycemic control Reduce the risk of complications

due to diabetes Before beginning any program,

make sure to undergo a medical evaluation Macrovascular complications Microvascular complications

Cardiovascular System A graded exercise test may be helpful

Age > 35 Type I diabetes of > 15 years Presence of any additional risk factors for

coronary artery disease Presence of microvascular disease Peripheral vascular disease Autonomic neuropathy

PAD

Peripheral Arterial Disease Evaluation is based on signs and

symptoms Intermittent claudication Cold feet Decreased or absent pulses Atrophy of subcutaneous tissues Hair loss

Retinopathy The eye examination schedule

should follow the ADA’s Clinical Practice Guidelines See chart

Those with proliferative diabetic retinopathy should avoid strenuous exercise Anaerobic exercise Exercise involving straining, jarring,

or Valsalva-like maneuvers

RetinopathyLevel of DR Acceptable

ActivitiesDiscouraged

ActivitiesOcular Reevaluation

No DR Dictated by medical status Dictated by medical status 12 months

Mild NPDR Dictated by medical status Dictated by medical status 6-12 months

Moderate NPDR Dictated by medical status Activities that dramatically elevate blood pressure:         Power lifting         Heavy Valsalva

4-6 months

Severe NPDR Dictated by medical status Activities that substantially increase systolic blood pressure, Valsalva maneuvers, and active jarring:         Boxing         Heavy competitive sports

2-4 months (may require laser surgery)

PDR Low-impact cardiovascular conditioning:         Swimming         Walking         Low-impact aerobics         Stationary cycling         Endurance exercises

Strenuous activities, Valsalva maneuvers, pounding or jarring:         Weight lifting          Jogging         High-impact aerobcs         Racquet sports         Strenuous trumpet playing

1-2 months (may require laser surgery)

         NPDR = nonproliferative diabetic retinopathy         PDR = Proliferative diabetic retinopathy

Nephropathy Specific exercise recommendations

have not been developed for patients with incipient or overt nephropathy

High-intensity or strenuous exercise should be avoided

Peripheral Neuropathy Loss of sensation in the feet Limits weight-bearing exercises

ContraindicatedTreadmillProlonged walkingJoggingStep exercises

RecommendedSwimmingBicyclingRowingChair exercisesArm exercisesOther non-weight bearing exercises

Autonomic Neuropathy Cardiac Autonomic Neuropathy

Resting tachycardia Orthostasis (fall in SBP >20 mmHg upon

standing) Other disturbances in autonomic nervous

system function involving the skin, pupils, GI, or genitourinary systems

Sudden death Silent myocardial ischemia Hypo/hypertension after vigorous exercise Difficulty with thermoregulation

Effects of Diabetic Autonomic Neuropathy on Exercise Silent myocardial ischemia Resting tachycardia and decreased

maximal responsiveness Decreased heart-rate variability Orthostasis/hypotension with exercise Exaggerated blood pressure responses

with supine position and exercise Loss of diuranal blood pressure

variation

Effects of Diabetic Autonomic Neuropathy on Exercise Cardiovascular and cardiorespiratory

instability Abnormal systolic ejection fractions at

rest/exercise Poor exercise tolerance Failure of pupil adaption to darkness Gastroparesis and diabetic diarrhea Hypoglycemia Decreased hypoglycemia awareness

Effects of Diabetic Autonomic Neuropathy on Exercise Hypoglycemia unresponsiveness Heat intolerance due to defective

sympathetic thermoregulation and sweating

Susceptibility to foot ulcers and limb loss due to disordered regulation of cutaneous blood flow

Incontinence

Exercise Precautions Postpone exercise if blood glucose

>300mg/dL or >240 mg/dL with urinary ketone bodies

Especially when beginning a program, monitor blood glucose before, during, and after exercise if taking insulin or oral agents

Adjustments in carbohydrate intake and/or insulin may be needed before testing and training; ingest carbohydrate if blood glucose is <80-100 mg/dL

Exercise Precautions Select proper footwear and follow appropriate

foot care steps to prevent ulcerations and other lesions of the foot

Wear shoes with silica gel or air mid-soles Wear polyester or blend (cotton/polyester)

socks to prevent blisters Keep the feet dry Ensure proper fitting footwear

Exercise Precautions Wear a diabetes identification bracelet

or shoe tag when exercising, and it should be clearly visible at all times

Avoid extremely hot or cold environments

Maintain proper hydration before, during, and after exercise

Exercise Precautions High resistance exercise using weights

are not acceptable for older individuals or those with long standing diabetes

Moderate weight training programs that utilize light weights and high repetitions can be used for all patients with diabetes

Guidelines for Avoiding Hypoglycemia

Consume carbohydrates (15-30 g) for every 30 minutes of moderate-intensity exercise

Consume a snack of slowly absorbed carbohydrate following prolonged exercise sessions

Avoid exercising muscle that underlies the injection site of short-acting insulin for 1 hour

Avoid late evening exercise

Guidelines for Avoiding Hypoglycemia

Decrease the insulin does: Intermediate-acting insulin—decrease by 30-35% on

the day of exercise Intermediate- and short-acting insulin—omit the dose of

short-acting insulin that precedes exercise Multiple doses of short-acting insulin—reduce the dose

prior to exercise by 30-50% and supplement carbohydrates

Continuous subcutaneous infusion—eliminate the mealtime bolus or increment that precedes or immediately follows exercise

Common Hypoglycemic Symptoms During Exercise Double or blurred

vision Abnormally elevated

pulse Fatigue Hand tremors /

shakiness Headache

Mental confusion Poor physical

coordination Tingling of hands or

tongue Visual spots Weakness

Refer to Charts Factors affecting blood glucose

management for acute and chronic exercise

Cardiopulmonary response to symptom-limited graded exercise in diabetics and controls

General Carbohydrate Increases for Endurance Activities

Preparing for Exercise Proper warm-up of 5-10 minutes of aerobic

activity at a low intensity level Stretch for 5-10 minutes, primarily focusing

on muscles that will be used during the exercise session

Cool down after the exercise session, taking about 5-10 minutes to gradually bring the heart rate down to its preexercise level

Exercise Prescription Frequency: 4-6 days per week or daily at low to

moderate intensity Duration: 20-60 minutes per session Intensity: 50-85% VO2max May need to use perceived exertion as an adjunct

to heart rate for monitoring exercise intensity. Exercising late in the evening increases risk of

nocturnal hypoglycemia Exercise caution when exercising in hot weather