Chapter 24 Chapter 24 Exercise Management

 Diabetes is a chronic metabolic disease characterized by an absolute or relative deficiency of insulin that results in hyperglycemia.  Clinical Overview (hyperlink) hyperlink  Clinical Criterion Fasting blood glucose > 125 mg/dl Fasting blood glucose > 125 mg/dl Random blood glucose > 200 mg/dl with hyperglycemic symptoms Random blood glucose > 200 mg/dl with hyperglycemic symptomshyperglycemic symptomshyperglycemic symptoms Two hour glucose > 200 mg/dl during an oral glucose tolerance test (OGTT) Two hour glucose > 200 mg/dl during an oral glucose tolerance test (OGTT)OGTT

Exercise Management  Blood glucose measurements that are bound to hemoglobin (HbA1c) provides an average blood glucose level over a prolonged period – days HbA1c  Individuals with diabetes are at risk for developing microvascular complications, including retinopathy and nephropathy; macrovascular disease; and various neuropathies (both autonomic and peripheral). Neuropathy can also enable silent ischemia. retinopathynephropathy macrovascular disease neuropathiesretinopathynephropathy macrovascular disease neuropathies

Exercise Management Type 1 Diabetes - In type 1 diabetes mellitus, there is an absolute deficiency of insulin caused by a marked reduction in insulin secreting beta cells of the pancreas.  Type 1 diabetics are prone to develop ketoacidosis when hypoinsulinemia results in hyperglycemia. ketoacidosis  The cause of type 1 diabetes is thought to involve an autoimmune response directed at the beta cells which are eventually destroyed.  The factors that trigger the autoimmune response have not been specifically identified but may include viruses or toxins.

Exercise Management Type 2 Diabetes - Individuals with Type 2 diabetes are considered to have a relative insulin deficiency because they may have elevated, reduced, or normal insulin levels but still present with hyperglycemia.  Thus, Type 2 diabetics present with hyperglycemia regardless of blood insulin status

Exercise Management  In type 2 diabetes, peripheral tissue insulin resistance and defective insulin secretion occur.  With insulin resistance, glucose does not readily enter the insulin-sensitive tissues (primarily muscle and adipose tissue), and hyperglycemia occurs.  The hyperglycemia causes the beta cells of the pancreas to secrete more insulin in an attempt to maintain a normal blood glucose concentration.

Exercise Management  The additional endogenous insulin is usually ineffective in lowering blood glucose and may further contribute to insulin resistance.  Eventually the beta cells may become exhausted and fail to produce adequate amounts of insulin.  The mechanisms underlying insulin resistance remain unclear but probably involve defects in the binding of insulin to its receptor and in post-receptor events such as glucose transport.  Obesity significantly increases insulin resistance, thus the majority of patients with type 2 diabetes are obese.

Exercise Management  Those with type 2 diabetes do not develop ketoacidosis except under conditions of unusual stress (e.g., trauma).  Family history is a risk factor for type 2 diabetes, and type 2 diabetes typically occurs after age 40.

Exercise Management Gestational Diabetes - Gestational diabetes occurs during pregnancy because of the contra-insulin effects of pregnancy (pregnancy hormones effect insulin uptake and production).  Risk factors for the development of gestational diabetes include family history of gestational diabetes, previous delivery of a large birth weight baby, and obesity  Approximately 50% of the women who develop gestational diabetes develop type 2 diabetes later in life.

Exercise Management Impaired Glucose Tolerance Impaired Glucose Tolerance and Impaired Fasting Glucose and Impaired Fasting Glucose Impaired glucose tolerance (IGT) and impaired fasting glucose (IFG) are intermediate metabolic conditions between normoglycemia clinical diabetes. (see link above)

Exercise Management Effects on the Exercise Response The effect of diabetes on a single exercise session is dependent on several factors, including:  use and type of medication to lower blood glucose (insulin or oral hypoglycemic agents)  timing of medication administration  blood glucose level prior to exercise timing, amount, and type of previous food intake  presence and severity of diabetic complications;  use of other medication secondary to diabetic complications,  the intensity, duration, and type of exercise.

Exercise Management Effects of Exercise Training  Possible improvement in blood glucose control with type 2 diabetes, but is not considered a component of treatment in type 1 diabetes to lower blood glucose ( must < 250 mg/dl for type 1 patient to exercise, no ketones ), but may improve CV health  Improved insulin sensitivity / lower medication requirement.  Reduction in body fat.  CV benefits  Prevention of Type 2 diabetes, especially those with IGT, hx of Gestational Diabetes, or family hx.

Exercise Management Diabetes Management and Meds  Insulin allows glucose to enter the cells of insulin sensitive tissue. There are several different types of insulin available pharmaceutically (injected or via insulin pump) that vary in onset, peak, duration, and source (see table 24.1 on page 185).  Oral agents for type 2 diabetes are medications that help the pancreas secrete more insulin, alter carbohydrate absorption, reduce liver glycogenolysis, and/or increase insulin sensitivity (see table 24.2 and 24.3 on pages ).

Exercise Management  The most significant effect of both insulin and oral hypoglycemic agents on exercise testing and exercise training is their ability to cause hypoglycemia. Attention to timing of medication, food intake, and blood glucose level before and after exercise is necessary.  If exercise is of long duration (i.e., > 60 min), blood glucose should be periodically tested during exercise.

Exercise Management Recommendations for Exercise Testing Exercise testing using protocols for populations at risk for coronary artery disease (CAD) is recommended in people who: have type 1 diabetes and are over the age of 30 have type 1 diabetes and are over the age of 30 have had type 1 diabetes longer than 15 years have had type 1 diabetes longer than 15 years have type 2 diabetes and are over age 35 have type 2 diabetes and are over age 35 have either type 1 or type 2 diabetes and one or more of the other CAD risk factors; have either type 1 or type 2 diabetes and one or more of the other CAD risk factors; have suspected or known CAD have suspected or known CAD have any microvascular or neurological diabetic complications. have any microvascular or neurological diabetic complications. See Table 24.4, p.187 (posted below) See Table 24.4, p.187 (posted below)

Exercise Management Recommendations for Exercise Testing Diabetic patients who do not meet any of the pervious criteria may be tested with protocols for the general healthy population. In these individuals, the primary objective is to: 1) Identify the presence and extent of CAD 2) Determine the appropriate intensity range for aerobic exercise testing. Diabetic patients who present chronotropic impairment during exercise are at a increased risk of MI and all cause mortality.

Exercise Management

Recommendations for Exercise Programming (see Table 24.5, pp , next slide)  The exercise prescription for people with diabetes must be individualized according to medication schedule, presence and severity of diabetic complications, and goals and expected benefits of the exercise program.  Food intake with exercise must be considered for type 1 individuals. These patients must have food supplies on hand during the exercise session. The amount of carbohydrate ingestion is dependent on the length of the exercise session.

Exercise Management

Recommendations for Exercise Programming Exercise is contraindicated if:  there is active retinal hemorrhage or there has been recent therapy for retinopathy (e.g., laser treatment)  illness or infection is present  blood glucose is above 250 mg/dl and ketones are present (blood glucose should be lowered before initiation of exercise) or  blood glucose is < 70 mg/dl because the risk of hypoglycemia is great (if postexercise blood glucose is < 100 mg/dl, carbohydrate should be eaten and blood glucose allowed to increase before the initiation of exercise)

Exercise Management Recommendations for Exercise Programming Exercise precautions include the following:  keeping a source of rapidly acting carbohydrate available during exercise  consuming adequate fluids before, during, and after exercise  practicing good foot care by wearing proper shoes and cotton socks, and inspecting feet after exercise;  carrying medical identification.

End of Presentation