Is Stress Making You Insulin Resistant? What Your Continuous Glucose Monitor Can Reveal
The following is an excerpt from the upcoming book, Hack Your Blood Sugar: Using a Continuous Glucose Monitor, due out January 30th, 2026
When your blood sugar keeps rising despite eating well, stress might be the hidden culprit—not food. Most of us quite rightly think the problem, and therefore the solution, will be food-related. But sometimes it's not the food. It's stress. So let's talk about the connection between stress, cortisol, and your blood sugar.
Cortisol is one of your stress hormones. These days, we tend to think of it as the bad guy. “Your cortisol is too high, that’s your problem!” But let’s remember that cortisol is actually super helpful. You want it, but you want the right amount at the right time. Let’s take a look at its natural rhythm and how it gets off track.
Understanding Cortisol’s Natural Circadian Rhythm
When life is relatively calm, your body has a predictable cortisol cycle. First thing in the morning, cortisol will naturally surge to its highest levels of the day. This gives you a boost and tells your liver to release extra glucose and fats into your bloodstream to fuel the most active parts of your day. This surge is provoked by morning sunlight. Cortisol then wanes to its lowest level in the evening around your habitual bedtime.
Why Cortisol Increases During Stress
When life becomes overly stressful, cortisol levels will increase. You’ll still have that morning surge, but levels may remain elevated later into the evening.
Cortisol is only trying to help.
Cortisol helps in several ways during a real disaster situation. First, it keeps you hypervigilant, alerting you to danger. High cortisol turns you into that wary cat on the fridge, hissing at everyone walking by. You’re always ready for a fight. I imagine cortisol helping the ancient human stay awake all night, keeping the fires lit to protect their loved ones from danger.
How Stress triggers cravings and fat storage
High cortisol also helps you store energy. It increases your cravings and helps you store fat for later. Think of how this could help you in a real disaster. Your metabolism is thriftier. When food is available, you’re better at storing that energy (as fat) for later to guard against starvation. Cortisol also increases your cravings for hyperpalatable foods. You don’t waste time on salads in an emergency! You want calorie-dense foods that give you the most bang for your buck. The high-cortisol brain seeks out more calories in less time. This is an important survival mechanism.
Of course, it’s unlikely that readers of this book are going to find themselves without food. Quite the opposite is usually true. So, the body’s survival strategies, instead of saving us, make our chronic health issues worse.
The Difference Between Acute Danger and Modern Chronic Stress
Unfortunately, our bodies don’t distinguish between the various causes of stress. War, famine, a judgmental mother-in-law, internet trolls, looming deadlines, traffic jams, long lines, or slow internet… they’re all the same to a body in stress.
Ways Elevated Cortisol Directly Affects Your Blood Sugar
Suppresses insulin production by the pancreas.
Decreases insulin sensitivity and increases protein breakdown in the muscles. This leads to insulin resistance and loss of muscle mass.
The liver produces more glucose when fasting (gluconeogenesis), so fasting glucose is higher.
Breaks down fat and sends free fatty acids into the bloodstream.
Stimulates your appetite and your cravings for “hyper-palatable foods.”
All of this increases the availability of glucose and fatty acids in the brain. This is fine in an acute situation. However, if it persists over the long term, it can lead to increased fat storage, reduced muscle mass, and chronically elevated blood sugar levels. This, in turn, increases insulin levels and contributes to the picture of metabolic syndrome and increased risk of cardiovascular disease.
Case Study: How Tax Season Spiked Ron’s Glucose Levels🤯📈
A great example of how stress can suppress insulin and raise blood sugar is with my patient, Ron.
Ron is a 68-year-old man who has type 2 diabetes. He is an example of someone with metabolic syndrome. He’s got elevated lipids, high blood pressure, and high glucose. He takes multiple glucose-lowering medications, a statin, and a blood pressure medication. He also has signs of kidney disease starting, which we definitely want to stop from progressing.
Ron had been working hard to make dietary changes and increase his exercise over the past 6 months, and his blood sugar was starting to stay in the Goldilocks Zone all day, most of the time. We were making plans to start reducing one of his medications.
But then tax season hit.
Ron is a CPA and runs his own business. Tax season is high stress for him. While Ron seems to take it in stride, the workload is heavy. I’ve had patients in this business before, so I prepared Ron with realistic expectations. I told him it was time to just hold steady and not focus on making big gains.
As expected, his blood sugar took a big turn for the worse.
Fortunately, his blood sugar didn’t backslide all the way to his starting point. If he took five steps forward in the previous six months, I’d say he took three steps back in the final three weeks of tax season. I was surprised by this because I thought we could hold steady or at least avoid backsliding more than one step.
What was even more fascinating was how quickly his high blood sugar resolved. As soon as April 16th arrived and he hit the road to head out of town, his blood sugar levels did a 180, and looked great again.
His eating didn’t change dramatically on April 16th, but his stress level did. He was relaxing with family and taking long walks in the morning. His blood sugar data looked much the same as it had before tax season!
Notice how, during a period of high stress before the tax deadline, blood sugar was routinely going well over 200 mg/dl. Once on vacation, Ron was able to keep his blood sugar in a healthier range more easily.
When I spoke to Ron and his wife a few weeks later, they remarked on how surprised they were at the impact stress had on his blood sugar levels. I could see them really turning this over and reflecting on how it was impacting his health.
That stress was causing more glucose to be released by his liver and was suppressing his already compromised insulin response. The result was a more pronounced glucose response to meals. The contrast between before and after tax season was stark.
The Power of Seeing Your Data with a CGM
We can talk about the impact of stress on our health until we’re blue in the face, but often it’s not until we are confronted with clear data showing the unequivocal impact of stress on our blood sugar and health that we’re motivated to do something about it.
To read more, order the book!✨🛒📚
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