Researchers have been exploring an unusual question: could putting insulin into the nose, the same medication used by people with diabetes, help restore the sense of smell? A systematic review published in 2026 set out to examine what the existing evidence says about nasal insulin for smell loss, and the early findings are cautiously encouraging.
What Did the Researchers Do?
The team searched four major medical databases for all existing studies on this topic, following strict international guidelines to make sure their review was thorough and consistent. They focused only on adults aged 18 and over whose smell loss was not caused by physical injury to the nose, nasal growths, or neurological conditions such as Parkinson’s disease.
What Did They Find?
Five studies involving 131 people (63 men and 68 women), aged between 16 and 56, met the criteria for inclusion. Key findings included:
- Nearly all studies used the same dose of insulin (40 IU).
- Blood sugar levels were checked in three studies and dropped only very slightly, suggesting the treatment was safe.
- Every single study found that participants’ sense of smell improved after using nasal insulin.
- The most common cause of smell loss across the studies was COVID-19.
- The most common delivery method was a small gelatin sponge soaked in insulin, placed directly into the nasal passage.
Why Might Insulin Work?
The nose contains insulin receptors in the olfactory mucosa, the tissue responsible for detecting smell. Insulin is thought to support the regeneration of olfactory sensory neurons, the nerve cells that detect odours. Applying insulin directly into the nose may encourage these cells to repair and regrow in a way that simply taking insulin by injection would not.
What Are the Limitations?
The review is promising but small. Only five studies were included, with a total of 131 participants, which is not enough to draw firm conclusions. The studies also varied in how they delivered the insulin and how they measured improvement. The authors recommend further well-designed clinical trials before nasal insulin can be officially recommended as a treatment.
It is also worth noting that most participants had smell loss related to COVID-19, so the findings may not apply equally to people whose smell loss has a different cause.
What Does This Mean for You?
Nasal insulin for smell loss is still experimental, and it is not currently available as a standard treatment. If you are interested in emerging therapies, it is worth raising with your ENT specialist: they can advise whether any clinical trials are underway that you might be eligible to join.
In the meantime, smell training remains the most widely recommended self-managed approach for olfactory recovery. If you are not yet doing it or want to make sure you are doing it effectively, take a look at how to benefit from smell training.
Key Takeaway
A 2026 systematic review found that nasal insulin improved smell function in every study reviewed, across 131 participants. The treatment appears safe, with only minor, temporary changes in blood sugar levels. However, the evidence base is still small and most participants had COVID-related smell loss. Nasal insulin is not yet an approved treatment. Speak to your specialist if you want to explore what options might be available to you.
