Blood Sugar

Air Pollution and Blood Sugar: Can Bad Air Really Push Your Numbers Up?

By the Blood Sugar Balance editorial desk · October 2026 · 8 min read

Most people never connect air pollution and blood sugar. You connect your numbers to the plate: the bread, the pasta, the slice of pie you should have skipped. So when your readings creep up during a week you ate exactly the same way, it feels like your body has stopped keeping its side of the deal.

My aunt Diane is the one who made me look into this. She is 64, a retired school secretary, and she lives in Riverside, California, about a mile from the freeway. She has managed type 2 diabetes for nine years with metformin, a careful kitchen and a notebook she fills in like a court reporter. Last summer, during the weeks the air was so bad the sky turned the color of weak tea, her numbers drifted up and stayed up. Same breakfast. Same walk around the block, when she could walk it. Higher numbers.

"I didn't change a thing," she told me on the phone. "So either the meter is broken or I am."

Neither was broken. And a study published this August suggests she was noticing something real.

What a 12-year study just found

On August 19, 2026, researchers published a study in the journal PLOS One that followed 9,671 adults with diabetes in the UK Biobank for a median of 12.4 years. They looked at how much traffic-type pollution each person lived with, and what happened to the small blood vessels in their eyes, kidneys and nerves.

The people in the most polluted areas had a 27% higher risk of those small-vessel complications with nitrogen dioxide, the gas that comes mostly from traffic, and a 44% higher risk with coarse particles, compared with the people breathing the cleanest air. That was after the researchers adjusted for the usual risk factors.

It is not the first study to point this way. A large cohort in India published in 2023 found that every rise of 10 micrograms per cubic meter in yearly fine-particle pollution was linked to a 22% higher risk of developing diabetes, and to small increases in fasting glucose and A1C.

Why bad air would have anything to do with sugar

This is the part nobody told Diane, and the part the AI summary at the top of your search page tends to skip.

The authors of the August study describe a chain that starts in the lungs and does not stay there. Fine particles and traffic gases set off inflammation that spreads through the body; people in the high-exposure groups had higher levels of CRP, a common blood marker of inflammation. They create oxidative stress, a kind of slow rusting inside the cells. And they appear to settle into the lining of the blood vessels, the thin layer that decides how well blood, oxygen and nutrients get where they need to go.

Inflammation and oxidative stress are two of the best-known drivers of insulin resistance. When the cells are inflamed, they answer insulin more slowly, so sugar stays in the blood longer. And when the small vessels are irritated, the tissues that should be pulling sugar out of the blood are getting less of what they need to do it.

Put simply: your body has its own system for keeping blood sugar in a healthy range, a feedback loop between your blood, your vessels and your cells. Bad air does not turn that loop off. It seems to make it sluggish, a little more every week you breathe it.

What Diane tried first, and what it left out

Diane did what a careful person does. All of it was reasonable, and some of it helped a little.

• She stayed inside on the worst days and bought an air purifier for the bedroom. It made the house easier to breathe in. Her numbers barely noticed.
• She tightened her diet even further, cutting the one piece of toast she still allowed herself. She was hungrier. Her readings stayed in the same band.
• She bought turmeric capsules from the pharmacy aisle, because a friend at church swore by them for her knees. Two months later she could not tell any difference on the meter.
• She asked her doctor about raising her metformin. Her doctor wanted to wait for the next A1C first.

Every one of those can work for some people, and none of them is a bad idea. But look at what they were aimed at. The purifier was aimed at the air. The diet was aimed at the food. The capsule was one ingredient on its own. None of them was aimed at the thing the researchers kept describing: the inflammation, the small vessels, and the slow loop between them.

Diane put it better than I can. "I kept fixing the plate," she said, "and the problem had moved somewhere else."

When rising numbers are a reason to call your doctor

Before what she does now, the part that matters most. If your readings keep climbing week after week, if they come with blurry vision, swelling in the feet, foamy urine, numbness or tingling, or constant thirst, call your doctor. The complications the August study measured are the kind that are caught at the eye exam and in a simple urine test, often years before you feel anything. Ask for both if it has been more than a year.

The bottle at her friend's kitchen table

Diane did not go looking for a supplement. She had just thrown one away.

The name came from Helen, a friend from her Wednesday quilting group, who has had diabetes longer than Diane has and lives off the same freeway. In September, Helen mentioned that her own summer numbers had not done what Diane's did. Diane, being Diane, asked what she was doing differently.

Helen got up, went to the cabinet next to the coffee maker, and set a white bottle with a green label on the table between their mugs.

Diane's first reaction, in her words: "Oh, Helen. Another one?"

So she did what she always does. She put on her reading glasses and read the whole label, front and side, the way she reads the fine print on a cell phone contract. Three things made her stop rolling her eyes.

The first was that it was not one ingredient. It was turmeric, the thing she had already tried, but next to it were ingredients she had never seen in a blood sugar product: cocoa bean extract, pine bark, butcher's broom. Ingredients for blood flow and inflammation, sitting next to ingredients for blood sugar. "That's the first one I've seen that's aimed at the vessels too," she said.

The second was how it was taken. One capsule a day, with the evening meal. "Even I can't mess that up," she said.

The third was the guarantee. The company's page gives you 60 days, and you can send back even the empty bottles. For a woman who had just thrown away two months of turmeric capsules, that was the line that mattered.

The bottle was CelluCare.

What is inside, and why each one matters here

The company says each capsule has more than 12 ingredients. These are the five Diane looked up on her tablet that night, and how each one lines up with what the August study described:

• Turmeric rhizome. The company lists it to support healthy blood sugar levels. It is also one of the most studied plant compounds for the body's inflammatory response, the first link in the chain the researchers described.
• Pine bark extract. Listed by the company for inflammation. This is the oxidative-stress side: the slow rusting that the study's authors called "a vicious cycle of oxidative damage."
• Cocoa bean extract. Listed to support blood flow. The cocoa compounds, the company's own references note, have been studied for metabolic health. This is the small-vessel side, the part the purifier and the diet never touched.
• Butcher's broom. Listed to support better blood circulation. Diane's comment: "My grandmother used to say this was for bad legs. I didn't know it was still around."
• Gymnema. Listed to support healthy blood sugar and heart health. A traditional herb that has been used for glucose metabolism for a long time.

Others on the label include eleuthero, for energy and fatigue, and banaba leaf. The company says the formula is assembled in the United States.

What changed, week by week

• Week 1. Nothing she could point to on the meter. She noticed she was less wiped out in the late afternoon, and she was not sure whether to believe it. The company itself says most people start feeling a difference after the first week, which made her suspicious that she was just expecting it.
• Weeks 2 and 3. Her readings stopped jumping around as much from one day to the next. A few mornings the number was back where it used to be before the summer.
• Month 1. Her notebook started to look like her old notebook. "Boring," she wrote at the bottom of one page. That is the highest compliment Diane gives anything.
• Months 2 and 3. Her feet stopped feeling cold at night, which she had not even realized was part of this. Her doctor will see the next A1C in November, and Diane is still on her metformin exactly as prescribed.

Why weeks and not days? Because inflammation, the lining of the blood vessels and the way cells answer insulin all change slowly. The company says its best results come when people take it consistently for three months or longer. That is why Diane's second order was the bigger one: she wanted enough time to actually find out, not to give up at week three. Individual results vary.

Who it is for, and who should ask a doctor first

It may be worth a look if you live near a busy road or in a place where the air gets bad, your numbers have been drifting up without a change in what you eat, you have already done the obvious things with food and movement, and you want something aimed at circulation and inflammation as well as blood sugar.

Talk to your doctor first, or skip it, if you have type 1 diabetes, you use insulin or a medication that can cause lows (gymnema works on the same thing), you take a blood thinner, you are pregnant or nursing, or you have a kidney or liver condition. A supplement is not a replacement for an eye exam, a urine test or your prescription.

Everything about it in one place

If your numbers climbed and your plate did not changeSee the capsule Diane keeps next to her coffee maker →

Diane started with enough for three months, for the reason above: the vessels and the inflammation do not change in a week, and she did not want to judge it at week three the way she judged the turmeric.

Sixty days, and even the empty bottles go backStart your own CelluCare try on the official site →

P.S. Last summer, Diane sat at her kitchen table under a sky the color of weak tea, looking at a number she had not earned, saying "either the meter is broken or I am." Neither was. If the air where you live has been bad and your notebook has been getting worse, this is the bottle Helen set on her table.

Continue reading What an A1C Number Does Not Show You Why two people with the same A1C can be having completely different days, and what to ask at the next appointment.