Ask the doctors: Did diet or exercise improve blood glucose readings?
Q: My doctor put me on a glucose monitor to track my blood sugar for a few weeks. There were three nights when my husband and I went walking after dinner, and those readings were better. He thinks it’s the walking, but I think it’s that I skipped dessert. Who do you think is right?
A: Considering this is a family debate, we are happy to be able to say that you are both correct. The behaviors you and your husband have identified — exercise vs. food choices — are quite different. However, they both bolster the body’s insulin response, which in turn helps maintain optimal blood sugar levels. The difference between the two actions lies in the mechanisms involved.
Skipping dessert reflects the well-known link between added sugars in the diet and increased blood glucose levels, which is likely why that explanation makes sense to you. Meanwhile, your husband appears to be drawing on the equally familiar concept that regular exercise plays an important role in blood sugar control.
It is also possible he has read about recent research showing that a post-meal walk can have a direct and immediate effect on moderating blood sugar. This occurs through a metabolic process that allows muscles to take up glucose through an alternative pathway that is less reliant on insulin.
In the study, published in 2022, researchers in the U.K. analyzed data from seven existing studies that examined the effects of exercise on blood glucose. They found that taking a walk after eating, even one as short as five minutes, improved blood sugar control. Changes in blood sugar were less extreme and more gradual.
That’s important because blood sugar spikes are suspected to play a role in Type 2 diabetes. Even better news: The beneficial effect of a post-meal walk lasted for up to 90 minutes. Interestingly, even standing for a few minutes after eating improved blood sugar numbers. However, for those individuals, the effect was far more modest.
We also want to point out that the continuous glucose monitor, or CGM, that your doctor asked you to use on a short-term basis is also emerging as a useful tool. These devices are easy to apply and last a few weeks. They deliver real-time data about the effects of diet and lifestyle on blood sugar levels. This can be particularly helpful for people whose blood sugar numbers are edging into the danger zone of prediabetes.
One of the challenges when it comes to diabetes is that elevated blood sugar is a so-called silent symptom. You can’t feel it when it’s happening. But with the data collected by a CGM, you can see the difference between how a doughnut or an apple affects glucose metabolism, or, on your husband’s side of the equation, the benefits of a post-meal walk.
In your own case, the short-term use of a CGM has validated your decision to skip dessert and may even have helped establish a new habit of a nightly post-meal walk for you and your husband.
• Dr. Eve Glazier is an internist and associate professor of medicine at UCLA Health. Dr. Elizabeth Ko is an internist and assistant professor of medicine at UCLA Health. Send your questions to askthedoctors@mednet.ucla.edu.
© 2026 UCLA Health. Distributed by Andrews McMeel Syndication