Question

For each aspect of physical exertion in people with insulin-dependent diabetes mellitus A–E, select the most appropriate option from the following list of physiological terms. 

1. Decreased insulin requirement. 

2. Increased insulin requirement. 

3. Hyperglycaemia. 

4. Hypoglycaemia. 

5. Parasympathetic effects. 

6. Sympathetic effects. 

A. Prior to a two-hour period of strenuous physical afternoon’s activity, diabetic patients require to increase their nutritional intake and adjust their dose of insulin compared with that taken before a sedentary afternoon. 

B. A major risk for such people is that they will develop a period of confusion during strenuous activity or during the following evening or night. 

C. During such a period of confusion, the patient often shows pallor and sweating. 

D. Prior to a period of strenuous activity it is reassuring rather than alarming to find the blood glucose around the renal threshold for glycosuria. 

E. After a full day of strenuous activity, the person with diabetes may set the alarm several times during the night so as to be able to test the blood glucose level. 

Answer 1

A. Option 1 Decreased insulin requirement. Prolonged strenuous exercise requires increased nutritional intake; with exercise, the insulin requirement for nutritional uptake into cells is much reduced. 

B. Option 4 Hypoglycaemia. As nutrients are depleted during exercise, even a reduced dose of insulin may lower the blood glucose level below that which will sustain normal cerebral activity; a falling glucose level causes progressively, confusion, coma and risk of brain damage and death. 

C. Option 6 Sympathetic effects. These effects give a useful clue to the diagnosis; sympathetic stimulation leads to skin vasoconstriction and sweating, also tremor and tachycardia; hypoglycaemia also activates the gastric vagus to increase secretion and activity, possibly inducing hunger and facilitating rapid transit of a remedial high-energy snack. 

D. Option 3 Hyperglycaemia. The renal threshold is about twice the normal fasting level; such transient hyperglycaemia is of little consequence compared with the risks of trying to keep the blood glucose normal and thereby risking the vastly greater danger of hypoglycaemia. 

E. Option 4 Hypoglycaemia. The blood glucose can dip severely some hours after prolonged exertion; nocturnal hypoglycaemia is particularly pernicious as the person may lapse into coma during sleep; it is much better to disturb sleep and confirm a threatening fall in blood glucose before it progresses to interfere with consciousness.