The Study
Insulin-mediated skeletal muscle vasodilation is nitric oxide dependent. A novel action of insulin to increase nitric oxide release.
This study watched what happens in people's legs when insulin is given. It saw that blood flow increases and that this change seems to involve a substance called nitric oxide. But because it didn’t randomly assign people to treatments like a strict experiment would, we can’t say for sure that insulin caused the change — only that they’re linked.
Analysis score
Maximum 44 for a cross-sectional study.
Where the score came from
Insulin tells the body's blood vessels in the legs to open up more by using a chemical called nitric oxide. It does this by turning up the body's ability to make nitric oxide in the blood vessel lining, not by making the muscles in the vessel more sensitive to it.
Where does this study sit?
Reviews of RCTs (Meta-analyses)
Max 100Randomized Trials
Max 90Reviews of Cohort Studies
Max 85Cohort Studies
Max 72Reviews of Case-Control Studies
Max 63Case-Control Studies
Max 58Cross-Sectional & Case Series
Max 50Expert Opinion
Max 538 / 100
Quality score
Snapshots of a population at a single point in time, or descriptions of small groups. Can identify correlations and prevalence, but cannot determine cause and effect.
Key takeaways
Summary
Based on the study abstract and findings.
- 1This shows insulin does more than control sugar—it directly improves blood flow, which helps deliver nutrients to muscles.
- 2Blood flow in the leg went from 0.30 to 0.48 liters per minute with insulin.
- 3When nitric oxide was blocked, blood flow dropped 20–45%.
- 440% of insulin’s effect came from nitric oxide, vs 20% without insulin.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
The Journal of clinical investigation
Year
1994
Authors
H. Steinberg, G. Brechtel, A. Johnson, N. Fineberg, A. Baron
Related Content
Claims (7)
When insulin is present, it helps blood vessels in muscles relax, letting more blood flow in. This brings more creatine to the muscle surface, where it can be absorbed.
When insulin levels go up in healthy adults, it helps blood flow better in the legs by turning on a molecule called nitric oxide — and it works about twice as well as when insulin isn’t active.
In healthy adults, insulin doesn't make blood vessels relax more when nitric oxide is already at work — meaning insulin probably doesn't improve blood flow by boosting the muscle's response to nitric oxide.
Insulin helps blood vessels relax better when the signal comes from the vessel lining, but not when the signal bypasses it—meaning insulin probably boosts the lining's ability to release a blood-vessel-relaxing chemical called nitric oxide.
When healthy adults get a certain drug in their leg artery, blood flow drops by up to 45%, and insulin makes this drop even bigger — showing that insulin helps control blood flow in muscles by affecting nitric oxide.
When insulin goes up in healthy people — without changing blood sugar — blood flow to the legs nearly doubles, showing insulin itself can widen blood vessels.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.