Which of the following is considered a long acting insulin?

Rationale: A. Lispro is a rapid-acting insulin analog characterized by a very quick onset of approximately 15 minutes. It is designed to be administered immediately before or after meals to control postprandial glucose spikes. It lacks the biochemical structure required to provide a sustained, basal level of insulin over a 24-hour period. B. Aspart is another rapid-acting insulin analog that utilizes recombinant DNA technology to ensure fast absorption into the systemic circulation. Like lispro, its duration of action is relatively short, typically lasting only 3 to 5 hours. It is used specifically for mealtime coverage and is not categorized as a long-acting or basal insulin. C. Glargine is a long-acting basal insulin analog that forms micro-precipitates upon subcutaneous injection, allowing for a slow and steady release into the bloodstream. It provides a relatively peakless profile that lasts approximately 24 hours, effectively mimicking the natural basal insulin secretion of the pancreas. It is essential for maintaining glycemic stability between meals and overnight. D. Regular insulin is classified as a short-acting insulin with an onset of 30 to 60 minutes and a peak effect around 2 to 3 hours. While it lasts longer than rapid-acting analogs, it does not provide the 24-hour coverage characteristic of long-acting formulations. It is primarily used for nutritional coverage or in intravenous emergency settings like ketoacidosis.