How long does Humulin R (regular insulin) last?
Humulin R (regular human insulin) typically has a total duration of action of about 6 to 8 hours, with effects starting to show within about 30 minutes after injection, peaking around 2 to 4 hours, and then tapering off afterward.
How long does Humulin N (NPH insulin) last?
Humulin N (isophane/NPH human insulin) usually lasts about 10 to 18 hours. It generally starts working within about 1 to 2 hours, peaks around 4 to 10 hours, and then declines gradually.
What about Humulin 70/30 or other premixed Humulin products?
Premixed Humulin products (such as 70/30, which mixes regular and NPH) combine a faster-acting component with a longer-acting one. That means their duration is typically closer to the NPH component (often roughly 12 to 18 hours), but the exact timing depends on the specific mix.
Why your “duration of action” can feel different day to day
Insulin duration and effect can vary based on injection site (abdomen vs. thigh vs. arm), dose, your insulin sensitivity, food timing, activity level, kidney function, and even the insulin temperature at use.
When to watch for lows
Because the strongest period differs by formulation (regular tends to peak earlier; NPH peaks later), the highest hypoglycemia risk usually lines up with the peak window. If you’re tracking symptoms or using CGM, you can often see the pattern that matches your product’s peak timing.
Which Humulin is yours matters
“Humulin” can refer to multiple formulations (R, N, 70/30, etc.), and their durations are not the same. If you tell me which exact one you’re using (for example, Humulin R, Humulin N, or 70/30) and your dose schedule (once daily vs. twice daily), I can give a more precise time course.
Sources
No sources were provided in the prompt.