Myth or fact: every blood sugar spike after eating is harmful

• A rise in glucose after eating is a normal response.
• In healthy people, glucose stays in the normal range most of the day.
• Responses to the same food vary widely between people.
• CGMs are useful in diabetes; benefits for healthy people are unproven.

Myth: every “glucose spike” damages your health

Over-the-counter CGMs have made glucose graphs a social media staple: a banana or oatmeal “spikes”, and influencers advise avoiding any spike to prevent aging, weight gain and fatigue.

Fact: rises after meals are normal physiology

Healthy people. A multicenter study of continuous glucose monitoring in adults without diabetes found that their glucose stayed within the normal range for the vast majority of the day and rose above it only briefly after meals (Shah et al., 2019).

Different “glucotypes”. Another study found that some people without a diabetes diagnosis have larger glucose swings. That is interesting for research, but it does not mean everyone needs a sensor (Hall et al., 2018).

Individual responses. A study of 800 people showed that responses to the same food vary widely (Zeevi et al., 2015). Universal lists of “spiking foods” on social media make little sense.

What really matters

• overall diet quality: more whole foods and fiber, fewer sugary drinks;
• physical activity, including a short walk after meals;
• sleep and a healthy weight;
• regular A1C and glucose testing if you have diabetes risk factors.