Diabetes Management: Exercise

Be familiar with the benefits and goals of exercise in DM.
•Improved blood glucose control in type 2

– Increases peripheral insulin sensitivity and glucose utilization

• Improved fitness

– Flexibility, endurance, muscle strength

• Decreased cardiovascular risk factors

– Improved blood lipids, decreased BP, decreased body weight (particularly important for type 2)

• Improved psychological well-being

Review the slides regarding the Response to Exercise in Absence of Diabetes.
Hormonal balance maintains euglycemia during

exercise under normal (non-DM) conditions

– Decreased insulin release

• Less circulating insulin restricts use of glucose by nonexercising

skeletal muscle, and facilitates lipolysis

• Level of insulin needed to facilitate glucose uptake by

exercising muscle is relatively minimal

– Increased counterregulatory hormones

• Glucagon (particularly important initially), catecholamines,

cortisol, GH (more prominent role in latter stages of prolonged

exercise)

• Stimulate muscle glycogenolysis, adipose tissue lipolysis, and

hepatic glucose production (glycogenolysis and

gluconeogenesis)

What is the major challenge for a type 1 diabetic with regard to exercise?
to avoid wide fluctuations in blood glucose
What are some of the key factors to consider with regard to exercise in a type 1 diabetic?
Factors to consider:

– Intensity, duration and type of exercise

– Fitness level

• Previous conditioning affects CHO storage

– Untrained: 13 g glycogen/kg muscle

– Trained – 32 g glycogen/kg muscle

– Nutritional state

• Affects glycogen stores

– Timing of exercise to when food was last eaten;

calories and content of meal

– State of metabolic control

• Affects the amount of stored CHO (i.e. glycogen)

because insulin availability determines the extent of

liver and muscle glycogen synthesis

• In an insulin-deficient person, resynthesis of glycogen

during post-exercise recovery is minimal (it’s an insulindependent

process)

• With adequate insulinization, the rate of glycogen

repletion after exercise is the same as in a non-diabetic

– Timing and type of insulin

What impact on blood glucose would it have if a person with poorly controlled diabetes (and insulin deficiency) were to exercise?
Diminished glucose uptake by the exercising muscle

• Abnormal increase in counterregulatory hormones

– Causes an exaggerated increase in hepatic glucose production

and circulating plasma glucose concentrations

• Further increase in plasma glucose, circulating free fatty acids (FFA),

and ketones

In other words, what effect does the state of metabolic control have on a diabetic’s ability to safely and effectively exercise?
Affects the amount of stored CHO (i.e. glycogen)

because insulin availability determines the extent of

liver and muscle glycogen synthesis

• In an insulin-deficient person, resynthesis of glycogen

during post-exercise recovery is minimal (it’s an insulindependent

process)

• With adequate insulinization, the rate of glycogen

repletion after exercise is the same as in a non-diabetic

What happens when an insulin deficient person exercises?
What happens when an insulin deficient person exercises?
What would be the impact of insulin excess on blood glucose levels during or after exercise?
hypoglycemia
What adjustments may be made to the dietary intake and/or insulin regimen in order to prevent exercise-induced hypoglycemia?
• Increase CHO intake before and/or after exercise

– 15 g CHO, 15 – 30 minutes before or after exercise of short

duration (<60 min) - 15 - 30 g CHO/hr during longer duration (>60 – 90 minutes)

• Decrease dosage of insulin acting during exercise activity

• General guidelines for adjusting insulin

– Reduce the dosage of insulin acting during the time of

exercise by 1 – 2 units

– Adjust insulin subsequent to (longer duration) activity by 1 –

2 units to prevent post-exercise hypoglycemia

– Keep records of BG and insulin adjustments (i.e. SMBG)

– Additional adjustments may be necessary for longer duration

exercise

Why might high intensity exercise beyond a person’s fitness level require supplemental insulin at the completion of exercise?
– High intensity exercise may require supplemental

insulin at the completion of exercise

• Exercise at too high an intensity for an individual’s fitness

level can cause release of “stress” (i.e. counter-regulatory)

hormones hyperglycemia

What adjustments in insulin dosage and/or food intake may need to be made with prolonged exercise?
– Prolonged exercise may require a decrease in

insulin dosage and/or an increase in food intake,

on the same day and the day after

• Up to 36 hours after prolonged exercise, liver and muscle

glycogen stores are repleted through prolonged glucose

uptake and stimulation of glycogen synthetase. During

this time there is improved glucose tolerance and

decreased insulin requirements.

• Post-exercise late-onset hypoglycemia can result from

inadequate adjustments in insulin and/or food intake.

How important is SMBG in managing an exercise program in a type 1 diabetic?
it’s essential both before and after exercise
What are the benefits and recommendations regarding exercise in type 2 diabetics?
Important component of management

• Improves blood lipids and increases sensitivity

to insulin

• Exercise 1 – 2 hours after meals can decrease postprandial

BG

• Exercise is unlikely to result in hypoglycemia

unless an individual is on insulin or certain

hypoglycemic agents (e.g. sulfonylureas)

• Moderately intense exercise (65 – 85% of max

HR) may lower risk of developing type 2 DM in

people at risk

Recommendations for exercise of type two diabetics:

150 min/wk of moderate-intensity aerobic physical activity spread over at least 3 days/wk with no more than 2 consecutive days without exercise – Grade A

resistance training at least 2 times per wk