Which type of insulin provides the longest duration of action?

Long-acting insulin is designed to provide a prolonged duration of action, typically lasting from 10 to 24 hours or more, depending on the specific formulation. This makes it particularly useful for maintaining stable blood glucose levels over an extended period, often required during the night and between meals.

Long-acting insulins, such as insulin glargine and insulin detemir, have a flat action profile, which means they release insulin steadily over time without the peaks associated with shorter-acting insulins. This characteristic helps reduce the risk of hypoglycemia and ensures that insulin is available for cellular uptake throughout the day and night.

In contrast, rapid-acting, short-acting, and intermediate-acting insulins are formulated for quick onset and shorter duration, which serves different clinical needs, such as managing blood sugar spikes related to meals. These insulins are not intended for long-term, steady baseline levels of insulin, which is why they do not have the same duration of action as long-acting insulin.