Which insulin preparation is long-acting and has no pronounced peak?

• A. Rapid-acting
• B. Short-acting
• C. Long-acting
• D. Ultra-long-acting

Answer: (C)

Long-acting insulins are designed to provide a steady basal level of insulin with a flat action curve and no pronounced peak. This smooth, background effect over roughly 24 hours helps control fasting glucose and reduces the risk of hypoglycemia that can occur with peak insulin levels. Classic examples like glargine and detemir are formulated to release insulin slowly after subcutaneous injection, giving near-constant activity rather than a sharp rise. Rapid-acting and short-acting insulins, by contrast, act quickly and have clear peaks that align with meals, not with basal needs. Ultra-long-acting insulins also have a very flat profile, but the standard label for this question is long-acting, which best fits the description of minimal peak and sustained effect.