After a running session, if a distance runner's blood glucose reads 3.8 mmol/L, what should be recommended?

A blood glucose level of 3.8 mmol/L is on the lower side of normal, indicating that the runner may be approaching hypoglycemia, especially after a prolonged running session. This condition can lead to symptoms such as fatigue, dizziness, or confusion if not addressed promptly.

In this context, recommending the consumption of 15 g of carbohydrate is appropriate. Carbohydrates can quickly raise blood glucose levels, providing the energy needed for recovery and preventing further decline into hypoglycemia. The 15-gram amount aligns with common recommendations for treating mild hypoglycemia and provides a quick source of glucose to replenish energy stores efficiently.

This approach directly addresses the immediate need to stabilize blood glucose levels and contrasts with other options that either do not provide an adequate or immediate solution, such as recommending protein, or are inappropriate for managing this situation, like measuring levels again without intervention or referring for glucagon treatment, which is typically reserved for severe hypoglycemic cases.