Exercise and Managing Blood Glucose

Case Study

Gregoire is a 20 year old university student living with type 1 diabetes for 10 years. He has been taught how to match his pre-meal (rapid-acting analogue) insulin dose to his carbohydrate intake. His A1C is 6.8% and he has minimal hypoglycemia. His meals are typically at 7 am, noon and 5:30 pm. He also takes a long-acting insulin analogue at bedtime, typically 10 pm.

He plans to join a soccer league with 1 hour games, 2 or 3 evenings per week. He discusses this with his diabetes educator. The plan is for Gregoire to check blood sugars more frequently for the first few weeks – before, during and after the game. As well Gregoire has agreed to try to eat 30 extra grams of carbohydrate before each game.

Gregoire comes back to see his diabetes educator 3 weeks later. His blood sugar records show he is having lows at 5AM or 6AM in the morning after most of his games.

Question 1: Which ONE of the following would NOT likely be contributing to Gregoire’s post-exercise hypoglycemia?

A.	Drinking 3 beers with his team after the games.
B.	The dose of his pre-supper rapid-acting insulin analogue.
C.	The dose of his basal insulin.
D.	The inability to eat his prescribed pre-exercise snack because he is still full after his supper.

Drinking 3 beers with his team after the games.	Incorrect. For people with type 1 diabetes, moderate consumption of alcohol with, or 2 or 3 hours after, an evening meal may result in delayed hypoglycemia overnight, the next morning or as late as 24 hours after alcohol consumption.
The dose of his pre-supper rapid-acting insulin analogue.	CORRECT. The timing of the hypoglycemic episodes falls outside of the time when the rapid-acting insulin analogue would be working. For a full discussion of physical activity and diabetes see: Chapter 10: Physical Activity and Diabetes.
The dose of his basal insulin.	Incorrect. Exercise performed late in the day or in the evening can be associated with increased risk of overnight hypoglycemia in people with type 1 diabetes. To reduce this risk, one can reduce bedtime intermediate or long-acting injected insulin dose, or reduce overnight basal insulin infusion rates by approximately 20% from bedtime to 3 am for insulin pump users.
The inability to eat his prescribed pre-exercise snack because he is still full after his supper.	Incorrect. The risk of hypoglycemia during exercise is of concern for people with type 1 diabetes. If pre-exercise blood glucose levels are < 5.5 mmol/L, approximately 15 to 30 g carbohydrate should be ingested before exercise. But Gregoire’s hypoglycemia is not occurring during exercise; rather, it’s occurring many hours later making it unlikely that the snack would be protective.

References for Gregoire:

• Chapter 10: Physical Activity and Diabetes