Woman wearing a CGM

Continuous glucose monitors and personalised nutrition

What is personalised nutrition?

Personalised nutrition aims to move beyond one-size-fits-all dietary advice. It uses detailed individual information about a person's body and health to provide more tailored nutrition advice (1).

There is no single agreed definition of personalised nutrition. In general, it refers to using information about an individual to develop more targeted nutrition advice, products, or services. This information may include dietary habits, physical characteristics, health measures, genetics, and lifestyle factors such as sleep, physical activity, and daily routines (2, 1).

Does personalised nutrition work?

Personalised nutrition may offer a more individual approach to dietary advice. However, an important question is whether it improves health more than general healthy-eating advice.

A recent review of randomised controlled trials, the type of study used to test whether an intervention causes a change, found promising but mixed results. Personalised nutrition approaches were linked with improvements in overall diet (diet quality) and in some measures of metabolic health, including blood glucose control, blood fats, and insulin sensitivity. However, the findings were not consistent across all outcomes. Most studies found no clear additional benefit for weight loss when personalised dietary advice was given, compared to generic dietary advice (3).

Diet consultation
Overall, personalised nutrition may help some people improve their diet quality and support aspects of metabolic health. However, more high-quality, long-term research is needed to understand which approaches work best, who is most likely to benefit, and whether any improvements can be maintained over time (3).

What are continuous glucose monitors?

There is growing interest in using digital health technologies, including continuous glucose monitors (CGMs), as part of personalised nutrition (4, 5). CGMs are small wearable devices that measure blood glucose at frequent intervals throughout the day and night. They show how blood glucose levels change over time.

CGMs are an established part of diabetes care, helping people with diabetes and healthcare professionals make informed decisions about lifestyle, diet, and medication. Several health authorities recommend their use for people with type 1 diabetes and for many people with type 2 diabetes who use insulin or other medications (6, 4).

CGMs are now also being explored for use by people without diabetes. In this setting, they may provide information about how blood glucose levels change in response to food and lifestyle factors. However, it is not yet clear whether monitoring these day-to-day changes improves health in healthy people or in people without diabetes (6, 8, 7).

How are CGMs used in personalised nutrition?

Some commercial programmes use CGM data to measure changes in blood glucose after meals and provide dietary advice based on how a person's blood glucose levels respond to different foods (8, 9, 10).

Image of woman with a CGM
CGMs can provide feedback in real time. This may help people notice how their blood glucose patterns change alongside food choices, physical activity, sleep, and other aspects of daily life. For some people, this feedback may support behaviour change. However, blood glucose readings can be difficult to interpret.

A person's blood glucose response to a food can vary naturally from one day to the next. This means that a response seen after eating a food on one occasion may not be the same every time that food is eaten. Advice based on only a small number of CGM readings may therefore be less reliable (9). It is also important to remember that a CGM shows changes in blood glucose levels. It does not show whether a food is healthy or less healthy.

Why do glucose levels change after eating?

It is normal for blood glucose levels to rise and fall during the day, especially after eating foods that contain carbohydrates. In people without diabetes, the body usually keeps these levels within a healthy range. When blood glucose levels rise after eating, the hormone insulin helps glucose move from the blood into the body's cells, helping to regulate blood glucose throughout the day.

Image of a CGM
A rise in blood glucose after eating is a normal response. It does not necessarily mean that a food is unhealthy or that there is a problem with blood glucose control. Greater clinical concern arises when blood glucose levels remain consistently high over time, as this may indicate impaired blood glucose regulation, as can happen in diabetes (11). The clinical significance of short-term blood glucose changes detected by CGMs in people without diabetes remains uncertain (11).

What affects blood glucose responses to food?

Blood glucose responses can differ substantially between people. They can also vary in the same person from one day to another. Many factors can influence these responses, including:

  • The amount of food eaten
  • The carbohydrate, fibre, protein, and fat content of a meal
  • How a food has been processed or prepared
  • Physical activity
  • Sleep
  • Stress
  • Illness
  • The timing of meals
  • Hormonal changes (6, 8)

As a result, the same person may have different blood glucose responses after eating the same food on different occasions. Research in adults without diabetes has found that blood glucose responses to identical meals can vary considerably when the meals are eaten on separate days. This suggests that a small number of post-meal readings may not reliably show a person's usual response to a particular food or meal (9).

Can focusing on blood glucose affect food choices?

One concern is that people may start to judge how healthy a food is by its effect on blood glucose levels. For example, someone may notice a rise in blood glucose after eating fruit or a starchy carbohydrate and decide to avoid it because they believe the rise is harmful (8).

A short-term rise in blood glucose after eating does not by itself show that a food is unhealthy. Looking only at blood glucose responses may overlook the wider nutritional value of foods, including their fibre, vitamins, minerals, and other beneficial components. It is therefore important to consider the overall diet, rather than judging individual foods based on their effects on blood glucose.

Research has raised concerns that an excessive focus on avoiding blood glucose rises could lead some people to unnecessarily restrict nutritious foods, potentially reducing overall diet quality (8). A recent review has also highlighted possible unintended effects of CGM use in people without diabetes, including increased health-related anxiety and worsening disordered eating behaviours. However, more research is needed to understand how often these effects occur and which individuals may be most at risk (6).

Image of fruit

Summary

While personalised nutrition may improve diet quality and some aspects of metabolic health, findings are not always consistent. Importantly, using more detailed personal data does not necessarily lead to greater health benefits. CGMs are increasingly being used as part of personalised nutrition. However, there is currently limited evidence that monitoring blood glucose responses provides meaningful health benefits for people without diabetes. While personalised nutrition and CGMs may have a role in future nutrition care, more high-quality, long-term research is needed to determine their effectiveness and identify who is most likely to benefit.

Last reviewed October 2026. Next review due October 2029.

References

  1. Ordovas JM, Ferguson LR, Tai ES, Mathers JC. Personalised nutrition and health. BMJ. 2018;361:k2173. 
  2. Martínez-González MA, Kim HS, Prakash V, Ramos-Lopez O, Zotor F, Martinez JA. Personalised, population and planetary nutrition for precision health. BMJ Nutr Prev Health. 2021;4(1):e000235. 
  3. Martinsen T, Brennan L. Key evidence for personalised nutrition: a review of randomised controlled trials. Food Funct. 2026;17:646-58. 
  4. Klonoff DC, Ahn D, Drincic A. Continuous glucose monitoring: a review of the technology and clinical use. Diabetes Res Clin Pract. 2017;133:178-92. 
  5. Moore JB. From personalised nutrition to precision medicine: the rise of consumer genomics and digital health. Proc Nutr Soc. 2020;79:300-10. 
  6. Dower JA, Johansson M, Camp AW, Montori VM, Lipska KJ. Continuous glucose monitoring in type 2 diabetes and beyond: a review. JAMA Intern Med. 2026.
  7. Liao X, Li Y, Tang S, Xiao Y, Yu X, Huang R, et al. Continuous glucose monitoring in non-diabetic populations: a systematic review of observational and interventional studies with meta-analysis. Eur J Med Res. 2026;31:397. 
  8. Guess N. The growing use of continuous glucose monitors in people without diabetes: an evidence-free zone. Pract Diabetes. 2023;40(5):19-22. 
  9. Hengist A, Ong JA, McNeel K, Guo J, Hall KD. Imprecision nutrition? Duplicate meals result in unreliable individual glycemic responses measured by continuous glucose monitors across four dietary patterns in adults without diabetes. medRxiv [Preprint]. 2023. 
  10. Zeevi D, Korem T, Zmora N, Israeli D, Rothschild D, Weinberger A, et al. Personalized nutrition by prediction of glycemic responses. Cell. 2015;163(5):1079-94. 
  11. Dimitriadis GD, Maratou E, Kountouri A, Board M, Lambadiari V. Regulation of postabsorptive and postprandial glucose metabolism by insulin-dependent and insulin-independent mechanisms: an integrative approach. Nutrients. 2021;13(1):159.
  12. Drabsch T, Holzapfel C. A scientific perspective of personalised gene-based dietary recommendations for weight management. Nutrients. 2019;11(3):617. 
  13. Hutchins KM, Betts JA, Thompson D, Hengist A, Gonzalez JT. Continuous glucose monitor overestimates glycemia, with magnitude of bias varying by postprandial test and individual-a randomized crossover trial. Am J Clin Nutr. 2025;121:1025-34. 
  14. Pemberton J, Brown A. Leveraging established continuous glucose monitor accuracy study methods to enhance research in people not living with diabetes. Am J Clin Nutr. 2025;121:1430-31. 

Disclaimer: The information on this page is for general information purposes only and should not be relied upon as medical, clinical or other professional advice. The WSRO is an international, member-based, not-for-profit organisation focused on the science of sugars and health. For more information about its members, please see our Members Directory.

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