In diabetes management, what is the rationale for basal-bolus insulin regimens and what is the concept of carb counting?

• A. Basal insulin covers meals; bolus covers fasting glucose; carb counting is irrelevant.
• B. Bolus insulin covers fasting glucose; basal covers meals; carb counting is used to reduce bolus doses.
• C. Carb counting is a fixed ratio independent of meals.
• D. Basal insulin covers fasting glucose; bolus rapid-acting insulin covers meals; carb counting uses carbohydrate intake to adjust bolus doses via insulin-to-carbohydrate ratios.

Answer: (D)