How Diabetes Affects Sense Of Smell

There are times we wish we could turn off our sense of smell: when changing diapers, when the dog just rolled in something foul, or when we’re stuck in line behind someone who hasn’t had a shower in a while. Funky odors can be distracting, overpowering, or even nauseating.

But we’d never want to give up our sense of smell entirely—not smelling the bad smells isn’t worth giving up how we feel when we inhale the scent of freshly baked bread, summer peaches, or a morning cup of coffee.

But for a small portion of the population, the sense of smell, or olfaction, begins to drift away until someone can’t enjoy their favorite fragrances. In rare cases, someone could lose their sense of smell altogether. Diabetes can contribute to a compromised sense of smell, and though it’s a subtle complication, the effects are far-reaching.

Here’s what you need to know about diabetes and your sense of smell:

How smell works

We perceive smell when molecules in the air are inhaled and then attach to receptors in the mucus membranes inside our noses. The receptors signal olfactory sensory neurons that send messages to the brain about the smells they’re perceiving (Hey! I smell waffles!).

We can perceive smell through the sensory neurons in our noses as well as through neurons at the roof of our throats. The neurons in our throats pick up smells from the food we eat. Sense of smell and sense of taste (gustation) are closely connected, and loss of smell tracks with loss of taste. If we lose our sense of smell, eating can be a chore.

If a smell is especially pungent, we can detect it through nerve endings in our eyes, nose, and mouth (think chemical smells or freshly cut onions).

What causes loss of smell?

Decreased sense of smell is called hyposmia, and complete loss of smell is called anosmia. When someone’s sense of smell changes so that traditionally pleasant smells are suddenly unpleasant or vice verse, someone has dysosmia. Someone can also experience phantoms smells—smells that aren’t really there.

A change or loss in sense of smell may be caused by:

• Nasal polyps
• Sinus or respiratory infections
• Trauma or injury to the head or nose
• Hormone imbalances
• Exposure to toxic chemicals
• Radiation or chemotherapy
• Certain medications
• Smoking
• Drug and alcohol abuse
• Aging
• Medical conditions including Parkinson’s disease, Alzheimer’s disease, multiple sclerosis, and diabetes

Diabetes and sense of smell

Studies have found a link between diabetes and olfactory dysfunction—either reduce sense of smell, lost sense of smell, or changed sense of smell. People with diabetes are also more likely to experience phantom odors.

A French study found that those with type 1 diabetes had poorer sense of smell than those without diabetes. Among the subjects who did have diabetes, greater age, diabetes duration, and peripheral neuropathy further increased risk for compromised sense of smell. A Canadian study also connected diabetes and impaired olfaction and found that the presence of neuropathic pain might contribute to poor sense of smell.

The common denominator of the research is that the more severe someone’s diabetes complications, the greater likelihood of impaired sense of smell.

Causes and Consequences

Loss of smell in those with diabetes may be caused by diabetic neuropathy, the nerve damage that high blood sugar causes over time. If the nerves that control sense of smell are damaged, they won’t be able to tell the brain what smells they’re sensing, or they may misinterpret those smells.

Somewhere between one and two percent of people in North America report having a smell disorder, and the percentage increases with age. Smell disorders are more common among men than women.

If you are experiencing a compromised sense of smell, talk to your doctor. Some underlying causes can be effectively treated, though the damage from neuropathy may be permanent. If your sniffer is working just fine, then take a moment to stop and smell the roses—and appreciate your sense of smell.