The short answer
Pharmacologic niacin can weaken regular human insulin’s glucose-lowering effect and worsen glucose control. This is different from claiming that ordinary food-level vitamin B3 causes the same risk.
What this answer covers
Oral niacin, especially pharmacologic nicotinic acid; dietary vitamin B3 and nicotinamide are different exposures.
- Supplement or preparation
- Niacin
- Medication ingredient
- insulin, regular, human
Regular-insulin labels name niacin
Both inspected concentrations list niacin among drugs that may reduce glucose lowering. Closer monitoring and clinician-directed treatment review may be needed.
Clinical evidence concerns a high-dose combination
A large vascular-risk trial of extended-release niacin plus laropiprant found more serious disturbances in diabetes control. It was not an glulisine-specific comparison, and laropiprant prevents attributing every outcome to niacin alone.
Dose and form matter
The trial concerned high-dose extended-release nicotinic acid with laropiprant. Its findings do not demonstrate the same risk from ordinary dietary vitamin B3 or every nicotinamide product.
Plan starting and stopping
Discuss pharmacologic niacin changes with the diabetes team and review glucose readings. No short spacing interval is established to prevent its systemic effect. Do not raise or lower insulin independently.
Evidence and practical considerations
Side effects & toxicity
Exact regular-insulin labels name niacin; narrowed to pharmacologic exposure and possible worsened glucose control.
- Exact scope
- Oral niacin, especially pharmacologic nicotinic acid; dietary vitamin B3 and nicotinamide are different exposures. with Regular human insulin RxCUI253182 IN; U100/U500 and routes distinct.
- Medication form and route
- injected regular human insulin; oral supplement
What remains uncertain
- No exact herb-event rate or arbitrary insulin change.
Factors that may matter: Concentration; Route; Meals; Product; Other diabetes treatment.
Read the supporting source summaries
Source 1: current product label
dailymed.nlm.nih.gov · Source check Sep 10, 2026
Population: People prescribed regular human insulin
Hypoglycemia can be severe. Niacin may decrease glucose lowering. Treatment changes can require increased monitoring and clinician review. Subcutaneous dose given30minutes before meals.
How this applies: Exact RxCUI253182 IN regular human insulin; U100/U500 distinguished from NPH and rapid analogs.
Product concentration, devices, route and action profile matter. No supplement-specific adverse-event incidence.
Source 2: current product label
dailymed.nlm.nih.gov · Source check Sep 10, 2026
Population: People prescribed regular human insulin
Hypoglycemia can be severe. Niacin may decrease glucose lowering. Treatment changes can require increased monitoring and clinician review. Subcutaneous dose given30minutes before meals. Concentration gives a different time course with both prandial and basal activity.
How this applies: Exact RxCUI253182 IN regular human insulin; U100/U500 distinguished from NPH and rapid analogs.
Product concentration, devices, route and action profile matter. No supplement-specific adverse-event incidence.
Source 3: original human study
pubmed.ncbi.nlm.nih.gov · Source check Sep 10, 2026
Population: 25,673high-vascular-risk adults.
High-dose niacin-laropiprant increased serious disturbances in diabetes control compared with placebo.
How this applies: Indirect for exact regular human insulin; source drug, preparation and endpoint retained.
Combination product, not ordinary nutritional niacin or a glipizide-specific estimate; no supplement need or protective spacing demonstrated. This does not establish an exact regular-human-insulin interaction.
Research assessment: · Open full citations ↗
Review and change history
- Publication status
- Published research summary
- Clinical review
- Not yet recorded
| Date | Update |
|---|---|
| Article prepared | |
| Prepared exact regular-insulin article with route, concentration and clinical endpoint boundaries. | |
| Research summary published |
Article revision: e8c7c14113835bfd
This guide brings together the evidence records used by our interaction checker. Each finding retains its own preparation limits, research date, and source summaries.
Full citations require verification. Reading this answer and the source summaries does not.
Taking other supplements or medications?
Use the checker to explore your other combinations. Ask a pharmacist to review the exact products, amounts and medical conditions in your complete list.
Open the interaction checkerInformation, not medical advice. Do not change prescribed treatment based on this guide.