Rapid-Acting Insulin: Onset, Peak and Meal Timing
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Rapid-acting insulin

Also called mealtime insulin, bolus insulin, fast-acting insulin, ultra rapid-acting insulin · Reviewed

Definition: Rapid-acting insulin is a mealtime insulin that starts working quickly and wears off within hours. NIDDK lists its onset at about 15 minutes, its peak at about 1 hour and its duration at 2 to 4 hours, or 5 to 7 hours for the ultra rapid-acting kind. Humalog, NovoLog, Fiasp, Lyumjev, Admelog and Apidra are examples.

When each label says to inject

Meal timing as each label states it
LabelWhen the dose is given
Humalog, AdmelogWithin 15 minutes before a meal or immediately after a meal
NovoLogWithin 5 to 10 minutes before a meal
ApidraWithin 15 minutes before a meal or within 20 minutes after starting a meal
Fiasp, LyumjevAt the start of a meal or within 20 minutes after starting the meal

By injection, these labels say the insulin is usually used alongside an intermediate or long-acting insulin, such as a basal insulin. In an insulin pump, the labels set how often the reservoir is changed: at least every 7 days for Humalog and NovoLog, every 6 days for Fiasp and every 9 days for Lyumjev.

What the labels warn about

Low blood sugar (hypoglycemia) is the most common reaction on every one of these labels. Because the effect comes on fast, a dose given and then a meal skipped or delayed matters more than with slower insulins. The labels also warn about low potassium and about pump failures, which can quickly lead to high blood sugar and ketoacidosis.

Why it matters for your log

Mealtime doses change from meal to meal. Logging the time of each dose next to the meal makes it easier to see later whether a low or high followed a dose given early, late or without food.

Read more on Dose Track: How long before a meal to inject mealtime insulin · Carb counting with mealtime insulin · Humalog side effects · NovoLog side effects

General education drawn from labels and published studies, not personal medical advice. Your prescriber, pharmacist and the label that came with your product are the final word.
Regular insulinRegular insulin is short-acting human insulin, the R in Humulin R and Novolin R. NIDDK lists its onset at… Basal insulinBasal insulin is long-acting insulin, usually injected once a day, that gives a steady background level of… Inhaled insulinInhaled insulin is mealtime insulin taken as a dry powder breathed in through an inhaler instead of… HypoglycemiaHypoglycemia means low blood glucose (blood sugar). MedlinePlus says that for many people with diabetes… Insulin pen (injection pen)An insulin pen is a prefilled device that holds several doses of a liquid medicine. You attach a new pen…

Frequently asked questions

How fast does rapid-acting insulin work?+
NIDDK lists an onset of about 15 minutes, a peak at about 1 hour and a duration of 2 to 4 hours, or 5 to 7 hours for ultra rapid-acting insulin. Timing varies from person to person.
Is rapid-acting insulin the same as regular insulin?+
No. NIDDK lists regular insulin separately: it starts in about 30 minutes and lasts 3 to 6 hours, so its labels give it about 30 minutes before meals.

Sources

  1. NIDDK (NIH): Insulin, medicines and other diabetes treatments
  2. Humalog (insulin lispro) US prescribing information, DailyMed
  3. NovoLog (insulin aspart) US prescribing information, DailyMed
  4. Apidra (insulin glulisine) US prescribing information, DailyMed
  5. Fiasp (insulin aspart) US prescribing information, DailyMed
  6. Lyumjev (insulin lispro-aabc) US prescribing information, DailyMed

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