In a basal-bolus insulin regimen for type 2 diabetes, which insulin is most appropriate for bolus dosing before meals?

• A. Humalog (insulin lispro)
• B. Lantus (insulin glargine)
• C. Humulin N (isophane insulin)
• D. Regular insulin (short-acting)

Answer: (A)

Covering a meal requires an insulin that acts quickly to match the rise in blood glucose after eating and then clears in time to prevent late hypoglycemia. Humalog (insulin lispro) is a rapid-acting insulin, starting to work in about 15 minutes, peaking in 1–2 hours, and lasting around 3–5 hours. This profile fits mealtime coverage well in a basal-bolus regimen, providing precise control of post-meal glucose with minimal carryover into the next meal.

Lantus is a long-acting basal insulin, designed to provide background coverage rather than to cover a meal, so it isn’t suitable for bolus dosing. Humulin N is intermediate-acting, with a slower onset and a longer, less predictable peak, which can misalign with meal glucose and increase hypoglycemia risk. Regular insulin is shorter-acting than lispro but still slower to start than rapid-acting analogs and has a longer, more unpredictable duration, making postprandial control less precise.

So the rapid-acting insulin lispro best matches the immediate post-meal glucose rise, making it the preferred bolus choice.