Why my blood sugar runs higher on my busiest workdays

The first time I noticed it, I assumed the sensor was off.

I’d had the same breakfast I eat most mornings, the same lunch, and roughly the same amount of walking as the day before. But by mid-afternoon my glucose was sitting higher than it had on a quiet writing day earlier that week. The only real difference was the calendar. One day was mostly admin and drafting at my desk. The other was client sessions, one after another, with a short gap for lunch that I spent answering email.

I went looking for a food explanation because food is where we’re taught to look. There wasn’t one. What my body was responding to was the workday itself.

Stress raises blood sugar, with or without a meal

I’ve written before about how stress drives insulin resistance and what twenty minutes outside does to your stress, so here’s only the short version.

When your body senses a demand, it releases stress hormones, mainly cortisol and adrenaline. One of their jobs is to make fuel available fast. They signal the liver to release stored glucose into the blood, and they make your cells a bit less responsive to insulin for a while, so the sugar stays in circulation where your muscles could grab it for a sprint.

That’s a sensible system for a body that might have to run. A body sitting in a video call doesn’t run anywhere. The glucose arrives, mostly goes unused, and has to be cleared the slow way. If you’re already insulin resistant, as I am, clearing it takes longer still.

So a demanding day can raise your numbers even when every meal was a good one. For anyone managing prediabetes who has ever said “but I ate so well today,” this is often part of the answer.

What a heavy workday looks like from the inside

The stress response is only one piece. What makes busy days so hard on blood sugar is that stress rarely travels alone. On my heaviest days, it tends to come with a whole chain of small things:

• Lunch eaten fast, at the desk, half-reading something.
• Three or four hours without standing up for more than a refill.
• A second coffee around two, because the afternoon block is long.
• Evening email that “only takes a minute” and keeps my head in work mode until bedtime.
• A shorter, choppier night, which means the next morning starts with a bit less insulin sensitivity than the one before.

None of these is dramatic. Each one is a reasonable decision on a busy day. But they all push in the same direction, and they stack. A hard week can show up in the next morning’s fasting number, and a hard season can show up in your A1C three months later, because A1C averages everything, including the stretch when a big project ate your spring.

What I find interesting is that the work I do makes this worse, even though I love it. An hour of coaching is an hour of full attention. Listening closely, staying calm and warm while someone tells me about the hardest part of their year. My body treats that as effort, because it is. I suspect the same goes for anyone whose job is people: therapists, teachers, nurses, managers, anyone who spends the day holding space for someone else.

The Boulder version of a heavy day

Living here adds one more layer, and I recognize it in myself.

In Boulder, a busy workday often starts with a hard workout. A run up Mount Sanitas before the first call, intervals on the bike, a 6am strength class, then straight into a full calendar. I love that about this town, and my own mornings start with movement too. But when I first wore a glucose monitor, it showed me something I didn’t expect: a hard workout could send my blood sugar up for a while afterward. My walks never did that. The tougher sessions sometimes did.

It fits the mechanism above. Intense exercise is a demand, and the body answers it with the same stress hormones that tell the liver to release glucose. On its own that’s fine, and regular training improves insulin sensitivity over time. The trouble starts when the hard session is only the first item in a long, stressful day. A tempo run at six, back-to-back meetings until three, a lunch that never quite happens, an evening event on Pearl Street, and a race on Saturday. Boulder applauds every one of those choices. Added up, it’s a lot of load for one body with very little recovery in between.

I’m not going to tell anyone here to train less. I’d count the workout as part of the day’s load, the same way I count client sessions. On days already stacked with meetings, I pick the walk or the yoga and save the big efforts for days with more room around them. (If you live here and want the other side of this, I wrote about why living in one of America’s healthiest cities isn’t a health plan.

What I changed about how my days are built

Trying to feel less stressed on client days would have been one more thing to fail at. So I changed the structure around the stress instead, to give my body a chance to use or clear what it was being handed.

I cap how many sessions run back to back. Three in a row is my limit now. After that there’s a gap, even a short one. For twenty years I told wellness business owners the same thing about their launch calendars. Build the recovery into the schedule, because it never shows up on its own.

The hardest meeting gets a walk after it. Ten minutes around the block. Working muscles pull glucose out of the blood without needing much help from insulin, which makes a short walk one of the most direct ways to use up the fuel a stressful hour put into circulation. It also gets me out of the chair, which is its own reward by mid-afternoon.

Lunch happens away from the desk, before the afternoon block. Plate at the table and the phone in another room. It takes fifteen minutes. I eat a little slower without trying, and I go into the afternoon with an actual meal in me instead of whatever I grazed on between calls.

The workday has an end. Email stops at a set time, and the last hour of the evening belongs to winding down. I wrote about my evening routine in The bookends of my day. On heavy client days I protect it even more, because that’s when my sleep most needs the help.

What strikes me is how unexciting all of this is. No supplement, no protocol, no special food. Just a calendar arranged so my body gets a break between demands.

If you don’t wear a glucose monitor

You don’t need a sensor to use any of this. Plenty of people managing prediabetes never wear one, and a CGM is only one way of seeing what your body is already telling you.

Look at the shape of your week instead. Where are the days that run back to back with no gap? When do you eat lunch on those days, and where? What happens to your evening after a heavy one? If you’ve had an A1C or fasting glucose result that didn’t match how carefully you’ve been eating, it’s worth asking whether the three months before that test were an unusually demanding stretch at work. If you train hard, check your training log for the same months. A marathon build that overlapped with your busiest quarter is exactly the kind of stacking I mean.

That’s also useful information for your doctor. “My numbers went up during the quarter I was working sixty-hour weeks” is a very different conversation from “my numbers went up and I don’t know why.”

Start with one day

If this rings true, don’t overhaul your whole week. Pick your hardest regular workday, the one you already dread a little on Sunday night, and change one thing about how it’s built. A walk after the toughest meeting. Lunch away from the screen. A firm stop time for email. Try it for a month and notice how the day feels, and the evening after it.

This article is meant for education and encouragement. It works best alongside the care of your own medical team, never in place of it.