What is the key difference between basal and bolus insulin?

The key difference between basal and bolus insulin is highlighted by the function of each type with respect to blood sugar control. Basal insulin is designed to provide a constant level of insulin in the bloodstream, helping to manage blood sugar levels throughout the day and night, regardless of food intake. This long-acting insulin mimics the steady slow release of insulin that the pancreas provides in a healthy individual, ensuring that glucose is metabolized between meals and during fasting periods.

In contrast, bolus insulin is fast-acting and is specifically administered at mealtimes to handle the rapid rise in blood glucose that occurs when food is consumed. This type of insulin is aimed at controlling the immediate increase in blood sugar levels following meals, allowing for more precise management of postprandial glucose levels.

The other options do not correctly describe the essential differences between the two types of insulin. It's important to understand these distinctions to effectively manage diabetes, as both types serve unique and critical roles in overall blood sugar regulation.